vendor: make vendor-update

* Run `vmui-update`
* Document the changes in README.md and CHANGELOG.md

.github/dependabot.yml

@@ -0,0 +1,26 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
+  - package-ecosystem: "gomod"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+  - package-ecosystem: "bundler"
+    directory: "/docs"
+    schedule:
+      interval: "daily"
+  - package-ecosystem: "gomod"
+    directory: "/app/vmui/packages/vmui/web"
+    schedule:
+      interval: "weekly"
+  - package-ecosystem: "docker"
+    directory: "/"
+    schedule:
+      interval: "daily"
+  - package-ecosystem: "npm"
+    directory: "/app/vmui"
+    schedule:
+      interval: "weekly"

.github/workflows/check-licenses.yml

@@ -0,0 +1,23 @@
+name: license-check
+on:
+  push:
+    paths:
+      - 'vendor'
+  pull_request:
+    paths:
+      - 'vendor'
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+      - name: Setup Go
+        uses: actions/setup-go@main
+        with:
+          go-version: 1.16
+        id: go
+      - name: Code checkout
+        uses: actions/checkout@master
+      - name: Check License
+        run: |
+          make check-licenses

.github/workflows/main.yml

@@ -0,0 +1,43 @@
+name: main
+on:
+  - push
+  - pull_request
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+      - name: Setup Go
+        uses: actions/setup-go@main
+        with:
+          go-version: 1.16
+        id: go
+      - name: Dependencies
+        run: |
+          go get -u golang.org/x/lint/golint
+          go get -u github.com/kisielk/errcheck
+          curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v1.29.0
+      - name: Code checkout
+        uses: actions/checkout@master
+      - name: Build
+        env:
+          GO111MODULE: on
+        run: |
+            export PATH=$PATH:$(go env GOPATH)/bin # temporary fix. See https://github.com/actions/setup-go/issues/14
+            make check-all
+            git diff --exit-code
+            make test-full
+            make test-pure
+            make test-full-386
+            make vminsert vmselect vmstorage
+            make vminsert-pure vmselect-pure vmstorage-pure
+            make vmutils
+            GOOS=freebsd go build -mod=vendor ./app/vminsert
+            GOOS=freebsd go build -mod=vendor ./app/vmselect
+            GOOS=freebsd go build -mod=vendor ./app/vmstorage
+            GOOS=openbsd go build -mod=vendor ./app/vminsert
+            GOOS=openbsd go build -mod=vendor ./app/vmselect
+            GOOS=openbsd go build -mod=vendor ./app/vmstorage
+            GOOS=darwin go build -mod=vendor ./app/vminsert
+            GOOS=darwin go build -mod=vendor ./app/vmselect
+            GOOS=darwin go build -mod=vendor ./app/vmstorage

.gitignore

@@ -7,5 +7,16 @@
 *.swp
 /gocache-for-docker
 /victoria-metrics-data
+/vmagent-remotewrite-data
 /vmstorage-data
 /vmselect-cache
+.DS_Store
+
+
+### terraform
+terraform.tfstate
+terraform.tfstate.*
+.terraform/
+Gemfile.lock
+/_site
+_site

.wwhrd.yml

@@ -0,0 +1,5 @@
+allowlist:
+  - Apache-2.0
+  - MIT
+  - BSD-3-Clause
+  - BSD-2-Clause

CODE_OF_CONDUCT.md

@@ -0,0 +1,76 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, sex characteristics, gender identity and expression,
+level of experience, education, socio-economic status, nationality, personal
+appearance, race, religion or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+ advances
+* Trolling, insulting/derogatory comments and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as physical or electronic
+ address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+ professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues and other contributions
+that are not aligned to this Code of Conduct or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project e-mail
+address, posting via an official social media account or acting as an appointed
+representative at an online or offline event. Representation of a project may be
+further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing or otherwise unacceptable behavior may be
+reported by contacting the project team at info@victoriametrics.com. All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate for the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+
+[homepage]: https://www.contributor-covenant.org
+
+For answers to common questions about this code of conduct, see
+https://www.contributor-covenant.org/faq

CODE_OF_CONDUCT_RU.md

@@ -0,0 +1,120 @@
+
+# Кодекс Поведения участника
+
+## Наши обязательства
+
+Мы, как участники, авторы и лидеры обязуемся сделать участие в сообществе
+свободным от притеснений для всех, независимо от возраста, телосложения,
+видимых или невидимых ограничений способности, этнической принадлежности,
+половых признаков, гендерной идентичности и выражения, уровня опыта,
+образования, социо-экономического статуса, национальности, внешности,
+расы, религии, или сексуальной идентичности и ориентации.
+
+Мы обещаем действовать и взаимодействовать таким образом, чтобы вносить вклад в открытое,
+дружелюбное, многообразное, инклюзивное и здоровое сообщество.
+
+## Наши стандарты
+
+Примеры поведения, создающие условия для благоприятных взаимоотношений включают в себя:
+
+* Проявление доброты и эмпатии к другим участникам проекта
+* Уважение к чужой точке зрения и опыту
+* Конструктивная критика и принятие конструктивной критики
+* Принятие ответственности, принесение извинений тем, кто пострадал от наших ошибок
+  и извлечение уроков из опыта
+* Ориентирование на то, что лучше подходит для сообщества, а не только для нас лично
+
+Примеры неприемлемого поведения участников включают в себя:
+
+* Использование выражений или изображений сексуального характера и нежелательное сексуальное внимание или домогательство в любой форме
+* Троллинг, оскорбительные или уничижительные комментарии, переход на личности или затрагивание политических убеждений
+* Публичное или приватное домогательство
+* Публикация личной информации других лиц, например, физического или электронного адреса, без явного разрешения
+* Иное поведение, которое обоснованно считать неуместным в профессиональной обстановке
+
+## Обязанности
+
+Лидеры сообщества отвечают за разъяснение и применение наших стандартов приемлемого
+поведения и будут предпринимать соответствующие и честные меры по исправлению положения
+в ответ на любое поведение, которое они сочтут неприемлемым, угрожающим, оскорбительным или вредным.
+
+Лидеры сообщества обладают правом и обязанностью удалять, редактировать или отклонять
+комментарии, коммиты, код, изменения в вики, вопросы и другой вклад, который не совпадает
+с Кодексом Поведения, и предоставят причины принятого решения, когда сочтут нужным.
+
+## Область применения
+
+Данный Кодекс Поведения применим во всех во всех публичных физических и цифровых пространства сообщества,
+а также когда человек официально представляет сообщество в публичных местах.
+Примеры представления проекта или сообщества включают использование официальной электронной почты,
+публикации в официальном аккаунте в социальных сетях,
+или упоминания как представителя в онлайн или оффлайн мероприятии.
+
+## Приведение в исполнение
+
+О случаях домогательства, а так же оскорбительного или иного другого неприемлемого
+поведения можно сообщить ответственным лидерам сообщества с помощью письма на info@victoriametrics.com
+Все жалобы будут рассмотрены и расследованы оперативно и беспристрастно.
+
+Все лидеры сообщества обязаны уважать неприкосновенность частной жизни и личную
+неприкосновенность автора сообщения.
+
+## Руководство по исполнению
+
+Лидеры сообщества будут следовать следующим Принципам Воздействия в Сообществе,
+чтобы определить последствия для тех, кого они считают виновными в нарушении данного Кодекса Поведения:
+
+### 1. Исправление
+
+**Общественное влияние**: Использование недопустимой лексики или другое поведение,
+считающиеся непрофессиональным или нежелательным в сообществе.
+
+**Последствия**: Личное, письменное предупреждение от лидеров сообщества,
+объясняющее суть нарушения и почему такое поведение
+было неуместно. Лидеры сообщества могут попросить принести публичное извинение.
+
+### 2. Предупреждение
+
+**Общественное влияние**: Нарушение в результате одного инцидента или серии действий.
+
+**Последствия**: Предупреждение о последствиях в случае продолжающегося неуместного поведения.
+На определенное время не допускается взаимодействие с людьми, вовлеченными в инцидент,
+включая незапрошенное взаимодействие 
+с теми, кто обеспечивает соблюдение Кодекса. Это включает в себя избегание взаимодействия
+в публичных пространствах, а так же во внешних каналах,
+таких как социальные сети. Нарушение этих правил влечет за собой временный или вечный бан.
+
+### 3. Временный бан
+
+**Общественное влияние**: Серьёзное нарушение стандартов сообщества,
+включая продолжительное неуместное поведение.
+
+**Последствия**: Временный запрет (бан) на любое взаимодействие 
+или публичное общение с сообществом на определенный период времени.
+На этот период не допускается публичное или личное взаимодействие с людьми,
+вовлеченными в инцидент, включая незапрошенное взаимодействие 
+с теми, кто обеспечивает соблюдение Кодекса.
+Нарушение этих правил влечет за собой вечный бан.
+
+### 4. Вечный бан
+
+**Общественное влияние**: Демонстрация систематических нарушений стандартов сообщества,
+включая продолжающееся неуместное поведение, домогательство до отдельных лиц,
+или проявление агрессии либо пренебрежительного отношения к категориям лиц.
+
+**Последствия**: Вечный запрет на любое публичное взаимодействие с сообществом.
+
+## Атрибуция
+
+Данный Кодекс Поведения основан на [Кодекс Поведения участника][homepage],
+версии 2.0, доступной по адресу
+https://www.contributor-covenant.org/version/2/0/code_of_conduct.html.
+
+Принципы Воздействия в Сообществе были вдохновлены [Mozilla's code of conduct
+enforcement ladder](https://github.com/mozilla/diversity).
+
+[homepage]: https://www.contributor-covenant.org
+
+Ответы на общие вопросы о данном кодексе поведения ищите на странице FAQ:
+https://www.contributor-covenant.org/faq. Переводы доступны по адресу
+https://www.contributor-covenant.org/translations.

CONTRIBUTING.md

@@ -0,0 +1,16 @@
+If you like VictoriaMetrics and want to contribute, then we need the following:
+
+- Filing issues and feature requests [here](https://github.com/VictoriaMetrics/VictoriaMetrics/issues).
+- Spreading a word about VictoriaMetrics: conference talks, articles, comments, experience sharing with colleagues.
+- Updating documentation.
+
+We are open to third-party pull requests provided they follow [KISS design principle](https://en.wikipedia.org/wiki/KISS_principle):
+
+- Prefer simple code and architecture.
+- Avoid complex abstractions.
+- Avoid magic code and fancy algorithms.
+- Avoid [big external dependencies](https://medium.com/@valyala/stripping-dependency-bloat-in-victoriametrics-docker-image-983fb5912b0d).
+- Minimize the number of moving parts in the distributed system.
+- Avoid automated decisions, which may hurt cluster availability, consistency or performance.
+
+Adhering `KISS` principle simplifies the resulting code and architecture, so it can be reviewed, understood and verified by many people.

LICENSE

@@ -175,7 +175,7 @@
 
    END OF TERMS AND CONDITIONS
 
-   Copyright 2019 VictoriaMetrics, Inc.
+   Copyright 2019-2021 VictoriaMetrics, Inc.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

Makefile

@@ -1,17 +1,27 @@
 PKG_PREFIX := github.com/VictoriaMetrics/VictoriaMetrics
 
+DATEINFO_TAG ?= $(shell date -u +'%Y%m%d-%H%M%S')
 BUILDINFO_TAG ?= $(shell echo $$(git describe --long --all | tr '/' '-')$$( \
-	      git diff-index --quiet HEAD -- || echo '-dirty-'$$(git diff-index -u HEAD | sha1sum | grep -oP '^.{8}')))
+	      git diff-index --quiet HEAD -- || echo '-dirty-'$$(git diff-index -u HEAD | openssl sha1 | cut -c 10-17)))
 
 PKG_TAG ?= $(shell git tag -l --points-at HEAD)
 ifeq ($(PKG_TAG),)
 PKG_TAG := $(BUILDINFO_TAG)
 endif
 
-GO_BUILDINFO = -X '$(PKG_PREFIX)/lib/buildinfo.Version=$(APP_NAME)-$(shell date -u +'%Y%m%d-%H%M%S')-$(BUILDINFO_TAG)'
+GO_BUILDINFO = -X '$(PKG_PREFIX)/lib/buildinfo.Version=$(APP_NAME)-$(DATEINFO_TAG)-$(BUILDINFO_TAG)'
+
+.PHONY: $(MAKECMDGOALS)
 
 all: \
-	victoria-metrics-prod
+	vminsert \
+	vmselect \
+	vmstorage
+
+all-pure: \
+	vminsert-pure \
+	vmselect-pure \
+	vmstorage-pure
 
 include app/*/Makefile
 include deployment/*/Makefile
@@ -19,46 +29,153 @@ include deployment/*/Makefile
 clean:
 	rm -rf bin/*
 
-release: victoria-metrics-prod
-	cd bin && tar czf victoria-metrics-$(PKG_TAG).tar.gz victoria-metrics-prod
+publish: \
+	publish-vminsert \
+	publish-vmselect \
+	publish-vmstorage
+
+package: \
+	package-vminsert \
+	package-vmselect \
+	package-vmstorage
+
+release: \
+	release-vmcluster
+
+release-vmcluster: \
+	release-vmcluster-amd64 \
+	release-vmcluster-arm64
+
+release-vmcluster-amd64:
+	GOARCH=amd64 $(MAKE) release-vmcluster-generic
+
+release-vmcluster-arm64:
+	GOARCH=arm64 $(MAKE) release-vmcluster-generic
+
+release-vmcluster-generic: \
+	vminsert-$(GOARCH)-prod \
+	vmselect-$(GOARCH)-prod \
+	vmstorage-$(GOARCH)-prod
+	cd bin && \
+		tar --transform="flags=r;s|-$(GOARCH)||" -czf victoria-metrics-$(GOARCH)-$(PKG_TAG).tar.gz \
+			vminsert-$(GOARCH)-prod \
+			vmselect-$(GOARCH)-prod \
+			vmstorage-$(GOARCH)-prod \
+		&& sha256sum victoria-metrics-$(GOARCH)-$(PKG_TAG).tar.gz \
+			vminsert-$(GOARCH)-prod \
+			vmselect-$(GOARCH)-prod \
+			vmstorage-$(GOARCH)-prod \
+			| sed s/-$(GOARCH)-prod/-prod/ > victoria-metrics-$(GOARCH)-$(PKG_TAG)_checksums.txt
+
+pprof-cpu:
+	go tool pprof -trim_path=github.com/VictoriaMetrics/VictoriaMetrics@ $(PPROF_FILE)
 
 fmt:
-	go fmt $(PKG_PREFIX)/lib/...
-	go fmt $(PKG_PREFIX)/app/...
+	GO111MODULE=on gofmt -l -w -s ./lib
+	GO111MODULE=on gofmt -l -w -s ./app
 
 vet:
-	go vet $(PKG_PREFIX)/lib/...
-	go vet $(PKG_PREFIX)/app/...
+	GO111MODULE=on go vet -mod=vendor ./lib/...
+	GO111MODULE=on go vet -mod=vendor ./app/...
 
 lint: install-golint
 	golint lib/...
 	golint app/...
 
 install-golint:
-	which golint || GO111MODULE=off go get -u github.com/golang/lint/golint
+	which golint || GO111MODULE=off go get golang.org/x/lint/golint
 
 errcheck: install-errcheck
 	errcheck -exclude=errcheck_excludes.txt ./lib/...
 	errcheck -exclude=errcheck_excludes.txt ./app/vminsert/...
 	errcheck -exclude=errcheck_excludes.txt ./app/vmselect/...
 	errcheck -exclude=errcheck_excludes.txt ./app/vmstorage/...
+	errcheck -exclude=errcheck_excludes.txt ./app/vmagent/...
+	errcheck -exclude=errcheck_excludes.txt ./app/vmalert/...
+	errcheck -exclude=errcheck_excludes.txt ./app/vmauth/...
+	errcheck -exclude=errcheck_excludes.txt ./app/vmbackup/...
+	errcheck -exclude=errcheck_excludes.txt ./app/vmrestore/...
+	errcheck -exclude=errcheck_excludes.txt ./app/vmctl/...
 
 install-errcheck:
-	which errcheck || GO111MODULE=off go get -u github.com/kisielk/errcheck
+	which errcheck || GO111MODULE=off go get github.com/kisielk/errcheck
+
+check-all: fmt vet lint errcheck golangci-lint
 
 test:
-	go test $(PKG_PREFIX)/lib/...
+	GO111MODULE=on go test -mod=vendor ./lib/... ./app/...
+
+test-race:
+	GO111MODULE=on go test -mod=vendor -race ./lib/... ./app/...
+
+test-pure:
+	GO111MODULE=on CGO_ENABLED=0 go test -mod=vendor ./lib/... ./app/...
+
+test-full:
+	GO111MODULE=on go test -mod=vendor -coverprofile=coverage.txt -covermode=atomic ./lib/... ./app/...
+
+test-full-386:
+	GO111MODULE=on GOARCH=386 go test -mod=vendor -coverprofile=coverage.txt -covermode=atomic ./lib/... ./app/...
 
 benchmark:
-	go test -bench=. $(PKG_PREFIX)/lib/...
+	GO111MODULE=on go test -mod=vendor -bench=. ./lib/...
+	GO111MODULE=on go test -mod=vendor -bench=. ./app/...
+
+benchmark-pure:
+	GO111MODULE=on CGO_ENABLED=0 go test -mod=vendor -bench=. ./lib/...
+	GO111MODULE=on CGO_ENABLED=0 go test -mod=vendor -bench=. ./app/...
 
 vendor-update:
-	go get -u
-	go mod tidy
-	go mod vendor
+	GO111MODULE=on go get -u -d ./lib/...
+	GO111MODULE=on go get -u -d ./app/...
+	GO111MODULE=on go mod tidy
+	GO111MODULE=on go mod vendor
+
+app-local:
+	CGO_ENABLED=1 GO111MODULE=on go build $(RACE) -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/$(APP_NAME)$(RACE) $(PKG_PREFIX)/app/$(APP_NAME)
+
+app-local-pure:
+	CGO_ENABLED=0 GO111MODULE=on go build $(RACE) -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/$(APP_NAME)-pure$(RACE) $(PKG_PREFIX)/app/$(APP_NAME)
+
+app-local-with-goarch:
+	GO111MODULE=on go build $(RACE) -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/$(APP_NAME)-$(GOARCH)$(RACE) $(PKG_PREFIX)/app/$(APP_NAME)
+
+app-local-windows-with-goarch:
+	CGO_ENABLED=0 GO111MODULE=on go build $(RACE) -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/$(APP_NAME)-windows-$(GOARCH)$(RACE).exe $(PKG_PREFIX)/app/$(APP_NAME)
 
 quicktemplate-gen: install-qtc
 	qtc
 
 install-qtc:
-	which qtc || GO111MODULE=off go get -u github.com/valyala/quicktemplate/qtc
+	which qtc || GO111MODULE=off go get github.com/valyala/quicktemplate/qtc
+
+
+golangci-lint: install-golangci-lint
+	golangci-lint run --exclude '(SA4003|SA1019|SA5011):' -D errcheck -D structcheck --timeout 2m
+
+install-golangci-lint:
+	which golangci-lint || curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(shell go env GOPATH)/bin v1.40.1
+
+install-wwhrd:
+	which wwhrd || GO111MODULE=off go get github.com/frapposelli/wwhrd
+
+check-licenses: install-wwhrd
+	wwhrd check -f .wwhrd.yml
+
+copy-docs:
+	echo "---\nsort: ${ORDER}\n---\n" > ${DST}
+	cat ${SRC} >> ${DST}
+
+# Copies docs for all components and adds the order tag.
+# Cluster docs are supposed to be ordered as 9th.
+# For The rest of docs is ordered manually.t
+docs-sync:
+	SRC=README.md DST=docs/Cluster-VictoriaMetrics.md ORDER=2 $(MAKE) copy-docs
+	SRC=app/vmagent/README.md DST=docs/vmagent.md ORDER=3 $(MAKE) copy-docs
+	SRC=app/vmalert/README.md DST=docs/vmalert.md ORDER=4 $(MAKE) copy-docs
+	SRC=app/vmauth/README.md DST=docs/vmauth.md ORDER=5 $(MAKE) copy-docs
+	SRC=app/vmbackup/README.md DST=docs/vmbackup.md ORDER=6 $(MAKE) copy-docs
+	SRC=app/vmrestore/README.md DST=docs/vmrestore.md ORDER=7 $(MAKE) copy-docs
+	SRC=app/vmctl/README.md DST=docs/vmctl.md ORDER=8 $(MAKE) copy-docs
+	SRC=app/vmgateway/README.md DST=docs/vmgateway.md ORDER=9 $(MAKE) copy-docs
+	SRC=app/vmbackupmanager/README.md DST=docs/vmbackupmanager.md ORDER=10 $(MAKE) copy-docs

app/victoria-metrics/Makefile

@@ -1,21 +0,0 @@
-# All these commands must run from repository root.
-
-victoria-metrics-prod:
-	APP_NAME=victoria-metrics $(MAKE) app-via-docker
-
-package-victoria-metrics:
-	APP_NAME=victoria-metrics \
-	$(MAKE) package-via-docker
-
-publish-victoria-metrics:
-	APP_NAME=victoria-metrics $(MAKE) publish-via-docker
-
-run-victoria-metrics:
-	mkdir -p victoria-metrics-data
-	DOCKER_OPTS='-v $(shell pwd)/victoria-metrics-data:/victoria-metrics-data -p 8428:8428 -p 2003:2003 -p 2003:2003/udp' \
-	APP_NAME=victoria-metrics \
-	ARGS='-graphiteListenAddr=:2003 -opentsdbListenAddr=:4242 -retentionPeriod=12 -search.maxUniqueTimeseries=1000000 -search.maxQueryDuration=10m' \
-	$(MAKE) run-via-docker
-
-victoria-metrics-arm:
-	CC=arm-linux-gnueabi-gcc CGO_ENABLED=1 GOARCH=arm GO111MODULE=on go build -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/victoria-metrics-arm ./app/victoria-metrics

app/victoria-metrics/deployment/Dockerfile

@@ -1,5 +0,0 @@
-FROM scratch
-COPY --from=local/certs:1.0.2 /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
-COPY bin/victoria-metrics-prod .
-EXPOSE 8428
-ENTRYPOINT ["/victoria-metrics-prod"]

app/victoria-metrics/main.go

@@ -1,60 +0,0 @@
-package main
-
-import (
-	"flag"
-	"net/http"
-	"time"
-
-	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert"
-	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmselect"
-	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmstorage"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/buildinfo"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
-)
-
-var httpListenAddr = flag.String("httpListenAddr", ":8428", "TCP address to listen for http connections")
-
-func main() {
-	flag.Parse()
-	buildinfo.Init()
-	logger.Init()
-	logger.Infof("starting VictoraMetrics at %q...", *httpListenAddr)
-	startTime := time.Now()
-	vmstorage.Init()
-	vmselect.Init()
-	vminsert.Init()
-
-	go httpserver.Serve(*httpListenAddr, requestHandler)
-	logger.Infof("started VictoriaMetrics in %s", time.Since(startTime))
-
-	sig := procutil.WaitForSigterm()
-	logger.Infof("received signal %s", sig)
-
-	logger.Infof("gracefully shutting down webservice at %q", *httpListenAddr)
-	startTime = time.Now()
-	if err := httpserver.Stop(*httpListenAddr); err != nil {
-		logger.Fatalf("cannot stop the webservice: %s", err)
-	}
-	vminsert.Stop()
-	logger.Infof("successfully shut down the webservice in %s", time.Since(startTime))
-
-	vmstorage.Stop()
-	vmselect.Stop()
-
-	logger.Infof("the VictoriaMetrics has been stopped in %s", time.Since(startTime))
-}
-
-func requestHandler(w http.ResponseWriter, r *http.Request) bool {
-	if vminsert.RequestHandler(w, r) {
-		return true
-	}
-	if vmselect.RequestHandler(w, r) {
-		return true
-	}
-	if vmstorage.RequestHandler(w, r) {
-		return true
-	}
-	return false
-}

app/vmagent/Makefile

@@ -0,0 +1,86 @@
+# All these commands must run from repository root.
+
+vmagent:
+	APP_NAME=vmagent $(MAKE) app-local
+
+vmagent-race:
+	APP_NAME=vmagent RACE=-race $(MAKE) app-local
+
+vmagent-prod:
+	APP_NAME=vmagent $(MAKE) app-via-docker
+
+vmagent-pure-prod:
+	APP_NAME=vmagent $(MAKE) app-via-docker-pure
+
+vmagent-amd64-prod:
+	APP_NAME=vmagent $(MAKE) app-via-docker-amd64
+
+vmagent-arm-prod:
+	APP_NAME=vmagent $(MAKE) app-via-docker-arm
+
+vmagent-arm64-prod:
+	APP_NAME=vmagent $(MAKE) app-via-docker-arm64
+
+vmagent-ppc64le-prod:
+	APP_NAME=vmagent $(MAKE) app-via-docker-ppc64le
+
+vmagent-386-prod:
+	APP_NAME=vmagent $(MAKE) app-via-docker-386
+
+package-vmagent:
+	APP_NAME=vmagent $(MAKE) package-via-docker
+
+package-vmagent-pure:
+	APP_NAME=vmagent $(MAKE) package-via-docker-pure
+
+package-vmagent-amd64:
+	APP_NAME=vmagent $(MAKE) package-via-docker-amd64
+
+package-vmagent-arm:
+	APP_NAME=vmagent $(MAKE) package-via-docker-arm
+
+package-vmagent-arm64:
+	APP_NAME=vmagent $(MAKE) package-via-docker-arm64
+
+package-vmagent-ppc64le:
+	APP_NAME=vmagent $(MAKE) package-via-docker-ppc64le
+
+package-vmagent-386:
+	APP_NAME=vmagent $(MAKE) package-via-docker-386
+
+publish-vmagent:
+	APP_NAME=vmagent $(MAKE) publish-via-docker
+
+run-vmagent:
+	mkdir -p vmagent-remotewrite-data
+	DOCKER_OPTS='-v $(shell pwd)/vmagent-remotewrite-data:/vmagent-remotewrite-data' \
+	ARGS='-remoteWrite.url=http://localhost:8428/api/v1/write' \
+	APP_NAME=vmagent \
+	$(MAKE) run-via-docker
+
+vmagent-amd64:
+	CGO_ENABLED=1 GOARCH=amd64 $(MAKE) vmagent-local-with-goarch
+
+vmagent-arm:
+	CGO_ENABLED=0 GOARCH=arm $(MAKE) vmagent-local-with-goarch
+
+vmagent-arm64:
+	CGO_ENABLED=0 GOARCH=arm64 $(MAKE) vmagent-local-with-goarch
+
+vmagent-ppc64le:
+	CGO_ENABLED=0 GOARCH=ppc64le $(MAKE) vmagent-local-with-goarch
+
+vmagent-386:
+	CGO_ENABLED=0 GOARCH=386 $(MAKE) vmagent-local-with-goarch
+
+vmagent-local-with-goarch:
+	APP_NAME=vmagent $(MAKE) app-local-with-goarch
+
+vmagent-pure:
+	APP_NAME=vmagent $(MAKE) app-local-pure
+
+vmagent-windows-amd64:
+	GOARCH=amd64 APP_NAME=vmagent $(MAKE) app-local-windows-with-goarch
+
+vmagent-windows-amd64-prod:
+	APP_NAME=vmagent $(MAKE) app-via-docker-windows-amd64

app/vmagent/README.md

@@ -0,0 +1,975 @@
+# vmagent
+
+`vmagent` is a tiny but mighty agent which helps you collect metrics from various sources
+and store them in [VictoriaMetrics](https://github.com/VictoriaMetrics/VictoriaMetrics)
+or any other Prometheus-compatible storage systems that support the `remote_write` protocol.
+
+<img alt="vmagent" src="vmagent.png">
+
+
+## Motivation
+
+While VictoriaMetrics provides an efficient solution to store and observe metrics, our users needed something fast
+and RAM friendly to scrape metrics from Prometheus-compatible exporters into VictoriaMetrics.
+Also, we found that our user's infrastructure are like snowflakes in that no two are alike. Therefore we decided to add more flexibility
+to `vmagent` such as the ability to push metrics instead of pulling them. We did our best and will continue to improve vmagent.
+
+
+## Features
+
+* Can be used as a drop-in replacement for Prometheus for scraping targets such as [node_exporter](https://github.com/prometheus/node_exporter). See [Quick Start](#quick-start) for details.
+* Can read data from Kafka. See [these docs](#reading-metrics-from-kafka).
+* Can write data to Kafka. See [these docs](#writing-metrics-to-kafka).
+* Can add, remove and modify labels (aka tags) via Prometheus relabeling. Can filter data before sending it to remote storage. See [these docs](#relabeling) for details.
+* Accepts data via all ingestion protocols supported by VictoriaMetrics:
+  * DataDog "submit metrics" API. See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-send-data-from-datadog-agent).
+  * InfluxDB line protocol via `http://<vmagent>:8429/write`. See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-send-data-from-influxdb-compatible-agents-such-as-telegraf).
+  * Graphite plaintext protocol if `-graphiteListenAddr` command-line flag is set. See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-send-data-from-graphite-compatible-agents-such-as-statsd).
+  * OpenTSDB telnet and http protocols if `-opentsdbListenAddr` command-line flag is set. See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-send-data-from-opentsdb-compatible-agents).
+  * Prometheus remote write protocol via `http://<vmagent>:8429/api/v1/write`.
+  * JSON lines import protocol via `http://<vmagent>:8429/api/v1/import`. See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-import-data-in-json-line-format).
+  * Native data import protocol via `http://<vmagent>:8429/api/v1/import/native`. See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-import-data-in-native-format).
+  * Prometheus exposition format via `http://<vmagent>:8429/api/v1/import/prometheus`. See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-import-data-in-prometheus-exposition-format) for details.
+  * Arbitrary CSV data via `http://<vmagent>:8429/api/v1/import/csv`. See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-import-csv-data).
+* Can replicate collected metrics simultaneously to multiple remote storage systems.
+* Works smoothly in environments with unstable connections to remote storage. If the remote storage is unavailable, the collected metrics
+  are buffered at `-remoteWrite.tmpDataPath`. The buffered metrics are sent to remote storage as soon as the connection
+  to the remote storage is repaired. The maximum disk usage for the buffer can be limited with `-remoteWrite.maxDiskUsagePerURL`.
+* Uses lower amounts of RAM, CPU, disk IO and network bandwidth compared with Prometheus.
+* Scrape targets can be spread among multiple `vmagent` instances when big number of targets must be scraped. See [these docs](#scraping-big-number-of-targets).
+* Can efficiently scrape targets that expose millions of time series such as [/federate endpoint in Prometheus](https://prometheus.io/docs/prometheus/latest/federation/). See [these docs](#stream-parsing-mode).
+* Can deal with [high cardinality](https://docs.victoriametrics.com/FAQ.html#what-is-high-cardinality) and [high churn rate](https://docs.victoriametrics.com/FAQ.html#what-is-high-churn-rate) issues by limiting the number of unique time series at scrape time and before sending them to remote storage systems. See [these docs](#cardinality-limiter).
+* Can load scrape configs from multiple files. See [these docs](#loading-scrape-configs-from-multiple-files).
+
+## Quick Start
+
+Please download `vmutils-*` archive from [releases page](https://github.com/VictoriaMetrics/VictoriaMetrics/releases), unpack it
+and configure the following flags to the `vmagent` binary in order to start scraping Prometheus targets:
+
+* `-promscrape.config` with the path to Prometheus config file (usually located at `/etc/prometheus/prometheus.yml`)
+* `-remoteWrite.url` with the remote storage endpoint such as VictoriaMetrics, the `-remoteWrite.url` argument can be specified multiple times to replicate data concurrently to an arbitrary number of remote storage systems.
+
+Example command line:
+
+```
+/path/to/vmagent -promscrape.config=/path/to/prometheus.yml -remoteWrite.url=https://victoria-metrics-host:8428/api/v1/write
+```
+
+If you only need to collect InfluxDB data, then the following command is sufficient:
+
+```
+/path/to/vmagent -remoteWrite.url=https://victoria-metrics-host:8428/api/v1/write
+```
+
+Then send InfluxDB data to `http://vmagent-host:8429`. See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-send-data-from-influxdb-compatible-agents-such-as-telegraf) for more details.
+
+`vmagent` is also available in [docker images](https://hub.docker.com/r/victoriametrics/vmagent/tags).
+
+Pass `-help` to `vmagent` in order to see [the full list of supported command-line flags with their descriptions](#advanced-usage).
+
+
+## Configuration update
+
+`vmagent` should be restarted in order to update config options set via command-line args.
+
+`vmagent` supports multiple approaches for reloading configs from updated config files such as `-promscrape.config`, `-remoteWrite.relabelConfig` and `-remoteWrite.urlRelabelConfig`:
+
+* Sending `SUGHUP` signal to `vmagent` process:
+  ```bash
+  kill -SIGHUP `pidof vmagent`
+  ```
+
+* Sending HTTP request to `http://vmagent:8429/-/reload` endpoint.
+
+There is also `-promscrape.configCheckInterval` command-line option, which can be used for automatic reloading configs from updated `-promscrape.config` file.
+
+
+## Use cases
+
+
+### IoT and Edge monitoring
+
+`vmagent` can run and collect metrics in IoT and industrial networks with unreliable or scheduled connections to their remote storage.
+It buffers the collected data in local files until the connection to remote storage becomes available and then sends the buffered
+data to the remote storage. It re-tries sending the data to remote storage until any errors are resolved.
+The maximum buffer size can be limited with `-remoteWrite.maxDiskUsagePerURL`.
+
+`vmagent` works on various architectures from the IoT world - 32-bit arm, 64-bit arm, ppc64, 386, amd64.
+See [the corresponding Makefile rules](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmagent/Makefile) for details.
+
+
+### Drop-in replacement for Prometheus
+
+If you use Prometheus only for scraping metrics from various targets and forwarding those metrics to remote storage
+then `vmagent` can replace Prometheus. Typically, `vmagent` requires lower amounts of RAM, CPU and network bandwidth compared with Prometheus.
+See [these docs](#how-to-collect-metrics-in-prometheus-format) for details.
+
+
+### Replication and high availability
+
+`vmagent` replicates the collected metrics among multiple remote storage instances configured via `-remoteWrite.url` args.
+If a single remote storage instance temporarily is out of service, then the collected data remains available in another remote storage instance.
+`vmagent` buffers the collected data in files at `-remoteWrite.tmpDataPath` until the remote storage becomes available again and then it sends the buffered data to the remote storage in order to prevent data gaps.
+
+
+### Relabeling and filtering
+
+`vmagent` can add, remove or update labels on the collected data before sending it to the remote storage. Additionally,
+it can remove unwanted samples via Prometheus-like relabeling before sending the collected data to remote storage.
+Please see [these docs](#relabeling) for details.
+
+
+### Splitting data streams among multiple systems
+
+`vmagent` supports splitting the collected data between muliple destinations with the help of `-remoteWrite.urlRelabelConfig`,
+which is applied independently for each configured `-remoteWrite.url` destination. For example, it is possible to replicate or split
+data among long-term remote storage, short-term remote storage and a real-time analytical system [built on top of Kafka](https://github.com/Telefonica/prometheus-kafka-adapter).
+Note that each destination can receive it's own subset of the collected data due to per-destination relabeling via `-remoteWrite.urlRelabelConfig`.
+
+
+### Prometheus remote_write proxy
+
+`vmagent` can be used as a proxy for Prometheus data sent via Prometheus `remote_write` protocol. It can accept data via the `remote_write` API
+at the`/api/v1/write` endpoint. Then apply relabeling and filtering and proxy it to another `remote_write` system .
+The `vmagent` can be configured to encrypt the incoming `remote_write` requests with `-tls*` command-line flags.
+Also, Basic Auth can be enabled for the incoming `remote_write` requests with `-httpAuth.*` command-line flags.
+
+
+### remote_write for clustered version
+
+While `vmagent` can accept data in several supported protocols (OpenTSDB, Influx, Prometheus, Graphite) and scrape data from various targets, writes are always peformed in Promethes remote_write protocol. Therefore for the [clustered version](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html), `-remoteWrite.url` the command-line flag should be configured as `<schema>://<vminsert-host>:8480/insert/<accountID>/prometheus/api/v1/write` according to [these docs](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#url-format). There is also support for multitenant writes. See [these docs](#multitenancy).
+
+## Multitenancy
+
+By default `vmagent` collects the data without tenant identifiers and routes it to the configured `-remoteWrite.url`. But it can accept multitenant data if `-remoteWrite.multitenantURL` is set. In this case it accepts multitenant data at `http://vmagent:8429/insert/<accountID>/...` in the same way as cluster version of VictoriaMetrics does according to [these docs](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#url-format) and routes it to `<-remoteWrite.multitenantURL>/insert/<accountID>/prometheus/api/v1/write`. If multiple `-remoteWrite.multitenantURL` command-line options are set, then `vmagent` replicates the collected data across all the configured urls. This allows using a single `vmagent` instance in front of VictoriaMetrics clusters for processing the data from all the tenants.
+
+
+## How to collect metrics in Prometheus format
+
+Specify the path to `prometheus.yml` file via `-promscrape.config` command-line flag. `vmagent` takes into account the following
+sections from [Prometheus config file](https://prometheus.io/docs/prometheus/latest/configuration/configuration/):
+
+* `global`
+* `scrape_configs`
+
+All other sections are ignored, including the [remote_write](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#remote_write) section.
+Use `-remoteWrite.*` command-line flag instead for configuring remote write settings.
+
+The following scrape types in [scrape_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config) section are supported:
+
+* `static_configs` - is for scraping statically defined targets. See [these docs](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#static_config) for details.
+* `file_sd_configs` - is for scraping targets defined in external files (aka file-based service discover).
+  See [these docs](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#file_sd_config) for details
+* `kubernetes_sd_configs` - for scraping targets in Kubernetes (k8s).
+  See [kubernetes_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#kubernetes_sd_config) for details.
+* `ec2_sd_configs` - is for scraping targets in Amazon EC2.
+  See [ec2_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#ec2_sd_config) for details.
+  `vmagent` doesn't support the `profile` config param yet.
+* `gce_sd_configs` - is for scraping targets in Google Compute Engine (GCE).
+  See [gce_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#gce_sd_config) for details.
+  `vmagent` provides the following additional functionality for `gce_sd_config`:
+  * if `project` arg is missing then `vmagent` uses the project for the instance where it runs;
+  * if `zone` arg is missing then `vmagent` uses the zone for the instance where it runs;
+  * if `zone` arg is equal to `"*"`, then `vmagent` discovers all the zones for the given project;
+  * `zone` may contain an arbitrary number of zones, i.e. `zone: [us-east1-a, us-east1-b]`.
+* `consul_sd_configs` - is for scraping the targets registered in Consul.
+  See [consul_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#consul_sd_config) for details.
+* `dns_sd_configs` - is for scraping targets discovered from DNS records (SRV, A and AAAA).
+  See [dns_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#dns_sd_config) for details.
+* `openstack_sd_configs` - is for scraping OpenStack targets.
+  See [openstack_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#openstack_sd_config) for details.
+  [OpenStack identity API v3](https://docs.openstack.org/api-ref/identity/v3/) is supported only.
+* `docker_sd_configs` - is for scraping Docker targets.
+  See [docker_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#docker_sd_config) for details.
+* `dockerswarm_sd_configs` - is for scraping Docker Swarm targets.
+  See [dockerswarm_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#dockerswarm_sd_config) for details.
+* `eureka_sd_configs` - is for scraping targets registered in [Netflix Eureka](https://github.com/Netflix/eureka).
+  See [eureka_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#eureka_sd_config) for details.
+* `digitalocean_sd_configs` is for scraping targerts registered in [DigitalOcean](https://www.digitalocean.com/)
+  See [digitalocean_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#digitalocean_sd_config) for details.
+* `http_sd_configs` is for scraping targerts registered in http service discovery.
+  See [http_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#http_sd_config) for details.
+
+Please file feature requests to [our issue tracker](https://github.com/VictoriaMetrics/VictoriaMetrics/issues) if you need other service discovery mechanisms to be supported by `vmagent`.
+
+`vmagent` also support the following additional options in `scrape_configs` section:
+
+* `disable_compression: true` - to disable response compression on a per-job basis. By default `vmagent` requests compressed responses from scrape targets
+  to save network bandwidth.
+* `disable_keepalive: true` - to disable [HTTP keep-alive connections](https://en.wikipedia.org/wiki/HTTP_persistent_connection) on a per-job basis.
+  By default, `vmagent` uses keep-alive connections to scrape targets to reduce overhead on connection re-establishing.
+* `series_limit: N` - for limiting the number of unique time series a single scrape target can expose. See [these docs](#cardinality-limiter).
+* `stream_parse: true` - for scraping targets in a streaming manner. This may be useful for targets exporting big number of metrics. See [these docs](#stream-parsing-mode).
+* `scrape_align_interval: duration` - for aligning scrapes to the given interval instead of using random offset in the range `[0 ... scrape_interval]` for scraping each target. The random offset helps spreading scrapes evenly in time.
+* `scrape_offset: duration` - for specifying the exact offset for scraping instead of using random offset in the range `[0 ... scrape_interval]`.
+* `relabel_debug: true` - for enabling debug logging during relabeling of the discovered targets. See [these docs](#relabeling).
+* `metric_relabel_debug: true` - for enabling debug logging during relabeling of the scraped metrics. See [these docs](#relabeling).
+
+Note that `vmagent` doesn't support `refresh_interval` option for these scrape configs. Use the corresponding `-promscrape.*CheckInterval`
+command-line flag instead. For example, `-promscrape.consulSDCheckInterval=60s` sets `refresh_interval` for all the `consul_sd_configs`
+entries to 60s. Run `vmagent -help` in order to see default values for the `-promscrape.*CheckInterval` flags.
+
+The file pointed by `-promscrape.config` may contain `%{ENV_VAR}` placeholders which are substituted by the corresponding `ENV_VAR` environment variable values.
+
+
+## Loading scrape configs from multiple files
+
+`vmagent` supports loading scrape configs from multiple files specified in the `scrape_config_files` section of `-promscrape.config` file. For example, the following `-promscrape.config` instructs `vmagent` loading scrape configs from all the `*.yml` files under `configs` directory plus a `single_scrape_config.yml` file:
+
+```yml
+scrape_config_files:
+- configs/*.yml
+- single_scrape_config.yml
+```
+
+Every referred file can contain arbitrary number of any [supported scrape configs](#how-to-collect-metrics-in-prometheus-format). There is no need in specifying top-level `scrape_configs` section in these files. For example:
+
+```yml
+- job_name: foo
+  static_configs:
+  - targets: ["vmagent:8429"]
+- job_name: bar
+  kubernetes_sd_configs:
+  - role: pod
+```
+
+`vmagent` dynamically reloads these files on `SIGHUP` signal or on the request to `http://vmagent:8429/-/reload`.
+
+
+## Adding labels to metrics
+
+Labels can be added to metrics by the following mechanisms:
+
+* The `global -> external_labels` section in `-promscrape.config` file. These labels are added only to metrics scraped from targets configured in the `-promscrape.config` file. They aren't added to metrics collected via other [data ingestion protocols](https://docs.victoriametrics.com/#how-to-import-time-series-data).
+* The `-remoteWrite.label` command-line flag. These labels are added to all the collected metrics before sending them to `-remoteWrite.url`. For example, the following command will start `vmagent`, which will add `{datacenter="foobar"}` label to all the metrics pushed to all the configured remote storage systems (all the `-remoteWrite.url` flag values):
+
+```
+/path/to/vmagent -remoteWrite.label=datacenter=foobar ...
+```
+
+
+## Relabeling
+
+`vmagent` and VictoriaMetrics support Prometheus-compatible relabeling.
+They provide the following additional actions on top of actions from the [Prometheus relabeling](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config):
+
+* `replace_all`: replaces all of the occurences of `regex` in the values of `source_labels` with the `replacement` and stores the results in the `target_label`.
+* `labelmap_all`: replaces all of the occurences of `regex` in all the label names with the `replacement`.
+* `keep_if_equal`: keeps the entry if all the label values from `source_labels` are equal.
+* `drop_if_equal`: drops the entry if all the label values from `source_labels` are equal.
+* `keep_metrics`: keeps all the metrics with names matching the given `regex`.
+* `drop_metrics`: drops all the metrics with names matching the given `regex`.
+
+The `regex` value can be split into multiple lines for improved readability and maintainability. These lines are automatically joined with `|` char when parsed. For example, the following configs are equivalent:
+
+```yaml
+- action: keep_metrics
+  regex: "metric_a|metric_b|foo_.+"
+```
+
+```yaml
+- action: keep_metrics
+  regex:
+  - "metric_a"
+  - "metric_b"
+  - "foo_.+"
+```
+
+The relabeling can be defined in the following places:
+
+* At the `scrape_config -> relabel_configs` section in `-promscrape.config` file. This relabeling is applied to target labels. This relabeling can be debugged by passing `relabel_debug: true` option to the corresponding `scrape_config` section. In this case `vmagent` logs target labels before and after the relabeling and then drops the logged target.
+* At the `scrape_config -> metric_relabel_configs` section in `-promscrape.config` file. This relabeling is applied to all the scraped metrics in the given `scrape_config`. This relabeling can be debugged by passing `metric_relabel_debug: true` option to the corresponding `scrape_config` section. In this case `vmagent` logs metrics before and after the relabeling and then drops the logged metrics.
+* At the `-remoteWrite.relabelConfig` file. This relabeling is aplied to all the collected metrics before sending them to remote storage. This relabeling can be debugged by passing `-remoteWrite.relabelDebug` command-line option to `vmagent`. In this case `vmagent` logs metrics before and after the relabeling and then drops all the logged metrics instead of sending them to remote storage.
+* At the `-remoteWrite.urlRelabelConfig` files. This relabeling is applied to metrics before sending them to the corresponding `-remoteWrite.url`. This relabeling can be debugged by passing `-remoteWrite.urlRelabelDebug` command-line options to `vmagent`. In this case `vmagent` logs metrics before and after the relabeling and then drops all the logged metrics instead of sending them to the corresponding `-remoteWrite.url`.
+
+You can read more about relabeling in the following articles:
+
+* [How to use Relabeling in Prometheus and VictoriaMetrics](https://valyala.medium.com/how-to-use-relabeling-in-prometheus-and-victoriametrics-8b90fc22c4b2)
+* [Life of a label](https://www.robustperception.io/life-of-a-label)
+* [Discarding targets and timeseries with relabeling](https://www.robustperception.io/relabelling-can-discard-targets-timeseries-and-alerts)
+* [Dropping labels at scrape time](https://www.robustperception.io/dropping-metrics-at-scrape-time-with-prometheus)
+* [Extracting labels from legacy metric names](https://www.robustperception.io/extracting-labels-from-legacy-metric-names)
+* [relabel_configs vs metric_relabel_configs](https://www.robustperception.io/relabel_configs-vs-metric_relabel_configs)
+
+
+## Prometheus staleness markers
+
+`vmagent` sends [Prometheus staleness markers](https://www.robustperception.io/staleness-and-promql) to `-remoteWrite.url` in the following cases:
+
+* If they are passed to `vmagent` via [Prometheus remote_write protocol](#prometheus-remote_write-proxy).
+* If the metric disappears from the list of scraped metrics, then stale marker is sent to this particular metric.
+* If the scrape target becomes temporarily unavailable, then stale markers are sent for all the metrics scraped from this target.
+* If the scrape target is removed from the list of targets, then stale markers are sent for all the metrics scraped from this target.
+* Stale markers are sent for all the scraped metrics on graceful shutdown of `vmagent`.
+
+Prometheus staleness markers aren't sent to `-remoteWrite.url` in [stream parsing mode](#stream-parsing-mode) or if `-promscrape.noStaleMarkers` command-line is set.
+
+
+## Stream parsing mode
+
+By default `vmagent` reads the full response from scrape target into memory, then parses it, applies [relabeling](#relabeling) and then pushes the resulting metrics to the configured `-remoteWrite.url`. This mode works good for the majority of cases when the scrape target exposes small number of metrics (e.g. less than 10 thousand). But this mode may take big amounts of memory when the scrape target exposes big number of metrics. In this case it is recommended enabling stream parsing mode. When this mode is enabled, then `vmagent` reads response from scrape target in chunks, then immediately processes every chunk and pushes the processed metrics to remote storage. This allows saving memory when scraping targets that expose millions of metrics. Stream parsing mode may be enabled in the following places:
+
+- Via `-promscrape.streamParse` command-line flag. In this case all the scrape targets defined in the file pointed by `-promscrape.config` are scraped in stream parsing mode.
+- Via `stream_parse: true` option at `scrape_configs` section. In this case all the scrape targets defined in this section are scraped in stream parsing mode.
+- Via `__stream_parse__=true` label, which can be set via [relabeling](#relabeling) at `relabel_configs` section. In this case stream parsing mode is enabled for the corresponding scrape targets. Typical use case: to set the label via [Kubernetes annotations](https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/) for targets exposing big number of metrics.
+
+Examples:
+
+```yml
+scrape_configs:
+- job_name: 'big-federate'
+  stream_parse: true
+  static_configs:
+  - targets:
+    - big-prometeus1
+    - big-prometeus2
+  honor_labels: true
+  metrics_path: /federate
+  params:
+    'match[]': ['{__name__!=""}']
+```
+
+Note that `sample_limit` option doesn't prevent from data push to remote storage if stream parsing is enabled because the parsed data is pushed to remote storage as soon as it is parsed.
+
+
+## Scraping big number of targets
+
+A single `vmagent` instance can scrape tens of thousands of scrape targets. Sometimes this isn't enough due to limitations on CPU, network, RAM, etc.
+In this case scrape targets can be split among multiple `vmagent` instances (aka `vmagent` horizontal scaling, sharding and clustering).
+Each `vmagent` instance in the cluster must use identical `-promscrape.config` files with distinct `-promscrape.cluster.memberNum` values.
+The flag value must be in the range `0 ... N-1`, where `N` is the number of `vmagent` instances in the cluster.
+The number of `vmagent` instances in the cluster must be passed to `-promscrape.cluster.membersCount` command-line flag. For example, the following commands
+spread scrape targets among a cluster of two `vmagent` instances:
+
+```
+/path/to/vmagent -promscrape.cluster.membersCount=2 -promscrape.cluster.memberNum=0 -promscrape.config=/path/to/config.yml ...
+/path/to/vmagent -promscrape.cluster.membersCount=2 -promscrape.cluster.memberNum=1 -promscrape.config=/path/to/config.yml ...
+```
+
+By default each scrape target is scraped only by a single `vmagent` instance in the cluster. If there is a need for replicating scrape targets among multiple `vmagent` instances,
+then `-promscrape.cluster.replicationFactor` command-line flag must be set to the desired number of replicas. For example, the following commands
+start a cluster of three `vmagent` instances, where each target is scraped by two `vmagent` instances:
+
+```
+/path/to/vmagent -promscrape.cluster.membersCount=3 -promscrape.cluster.replicationFactor=2 -promscrape.cluster.memberNum=0 -promscrape.config=/path/to/config.yml ...
+/path/to/vmagent -promscrape.cluster.membersCount=3 -promscrape.cluster.replicationFactor=2 -promscrape.cluster.memberNum=1 -promscrape.config=/path/to/config.yml ...
+/path/to/vmagent -promscrape.cluster.membersCount=3 -promscrape.cluster.replicationFactor=2 -promscrape.cluster.memberNum=2 -promscrape.config=/path/to/config.yml ...
+```
+
+If each target is scraped by multiple `vmagent` instances, then data deduplication must be enabled at remote storage pointed by `-remoteWrite.url`.
+See [these docs](https://docs.victoriametrics.com/#deduplication) for details.
+
+
+## Scraping targets via a proxy
+
+`vmagent` supports scraping targets via http, https and socks5 proxies. Proxy address must be specified in `proxy_url` option. For example, the following scrape config instructs
+target scraping via https proxy at `https://proxy-addr:1234`:
+
+```yml
+scrape_configs:
+- job_name: foo
+  proxy_url: https://proxy-addr:1234
+```
+
+Proxy can be configured with the following optional settings:
+
+* `proxy_authorization` for generic token authorization. See [Prometheus docs for details on authorization section](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config)
+* `proxy_bearer_token` and `proxy_bearer_token_file` for Bearer token authorization
+* `proxy_basic_auth` for Basic authorization. See [these docs](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config).
+* `proxy_tls_config` for TLS config. See [these docs](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#tls_config).
+
+For example:
+
+```yml
+scrape_configs:
+- job_name: foo
+  proxy_url: https://proxy-addr:1234
+  proxy_basic_auth:
+    username: foobar
+    password: secret
+  proxy_tls_config:
+    insecure_skip_verify: true
+    cert_file: /path/to/cert
+    key_file: /path/to/key
+    ca_file: /path/to/ca
+    server_name: real-server-name
+```
+
+## Cardinality limiter
+
+By default `vmagent` doesn't limit the number of time series each scrape target can expose. The limit can be enforced in the following places:
+
+- Via `-promscrape.seriesLimitPerTarget` command-line option. This limit is applied individually to all the scrape targets defined in the file pointed by `-promscrape.config`.
+- Via `series_limit` config option at `scrape_config` section. This limit is applied individually to all the scrape targets defined in the given `scrape_config`.
+- Via `__series_limit__` label, which can be set with [relabeling](#relabeling) at `relabel_configs` section. This limit is applied to the corresponding scrape targets. Typical use case: to set the limit via [Kubernetes annotations](https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/) for targets, which may expose too high number of time series.
+
+All the scraped metrics are dropped for time series exceeding the given limit. The exceeded limit can be [monitored](#monitoring) via `promscrape_series_limit_rows_dropped_total` metric.
+
+See also `sample_limit` option at [scrape_config section](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config).
+
+By default `vmagent` doesn't limit the number of time series written to remote storage systems specified at `-remoteWrite.url`. The limit can be enforced by setting the following command-line flags:
+
+* `-remoteWrite.maxHourlySeries` - limits the number of unique time series `vmagent` can write to remote storage systems during the last hour. Useful for limiting the number of active time series.
+* `-remoteWrite.maxDailySeries` - limits the number of unique time series `vmagent` can write to remote storage systems during the last day. Useful for limiting daily churn rate.
+
+Both limits can be set simultaneously. If any of these limits is reached, then samples for new time series are dropped instead of sending them to remote storage systems. A sample of dropped series is put in the log with `WARNING` level.
+
+The exceeded limits can be [monitored](#monitoring) with the following metrics:
+
+* `vmagent_hourly_series_limit_rows_dropped_total` - the number of metrics dropped due to exceeded hourly limit on the number of unique time series.
+* `vmagent_daily_series_limit_rows_dropped_total` - the number of metrics dropped due to exceeded daily limit on the number of unique time series.
+
+These limits are approximate, so `vmagent` can underflow/overflow the limit by a small percentage (usually less than 1%).
+
+
+## Monitoring
+
+`vmagent` exports various metrics in Prometheus exposition format at `http://vmagent-host:8429/metrics` page. We recommend setting up regular scraping of this page
+either through `vmagent` itself or by Prometheus so that the exported metrics may be analyzed later.
+Use official [Grafana dashboard](https://grafana.com/grafana/dashboards/12683) for `vmagent` state overview.
+If you have suggestions for improvements or have found a bug - please open an issue on github or add a review to the dashboard.
+
+`vmagent` also exports the status for various targets at the following handlers:
+
+* `http://vmagent-host:8429/targets`. This handler returns human-readable status for every active target.
+This page is easy to query from the command line with `wget`, `curl` or similar tools.
+It accepts optional `show_original_labels=1` query arg which shows the original labels per each target before applying the relabeling.
+This information may be useful for debugging target relabeling.
+* `http://vmagent-host:8429/api/v1/targets`. This handler returns data compatible with [the corresponding page from Prometheus API](https://prometheus.io/docs/prometheus/latest/querying/api/#targets).
+
+* `http://vmagent-host:8429/ready`. This handler returns http 200 status code when `vmagent` finishes it's initialization for all service_discovery configs.
+It may be useful to perform `vmagent` rolling update without any scrape loss.
+
+
+## Troubleshooting
+
+* We recommend you [set up the official Grafana dashboard](#monitoring) in order to monitor the state of `vmagent'.
+
+* We recommend you increase the maximum number of open files in the system (`ulimit -n`) when scraping a big number of targets,
+  as `vmagent` establishes at least a single TCP connection per target.
+
+* If `vmagent` uses too big amounts of memory, then the following options can help:
+  * Enabling stream parsing. See [these docs](#stream-parsing-mode).
+  * Reducing the number of output queues with `-remoteWrite.queues` command-line option.
+  * Reducing the amounts of RAM vmagent can use for in-memory buffering with `-memory.allowedPercent` or `-memory.allowedBytes` command-line option. Another option is to reduce memory limits in Docker and/or Kuberntes if `vmagent` runs under these systems.
+  * Reducing the number of CPU cores vmagent can use by passing `GOMAXPROCS=N` environment variable to `vmagent`, where `N` is the desired limit on CPU cores. Another option is to reduce CPU limits in Docker or Kubernetes if `vmagent` runs under these systems.
+
+* When `vmagent` scrapes many unreliable targets, it can flood the error log with scrape errors. These errors can be suppressed
+  by passing `-promscrape.suppressScrapeErrors` command-line flag to `vmagent`. The most recent scrape error per each target can be observed at `http://vmagent-host:8429/targets`
+  and `http://vmagent-host:8429/api/v1/targets`.
+
+* The `/api/v1/targets` page could be useful for debugging relabeling process for scrape targets.
+  This page contains original labels for targets dropped during relabeling (see "droppedTargets" section in the page output). By default the `-promscrape.maxDroppedTargets` targets are shown here. If your setup drops more targets during relabeling, then increase `-promscrape.maxDroppedTargets` command-line flag value to see all the dropped targets. Note that tracking each dropped target requires up to 10Kb of RAM. Therefore big values for `-promscrape.maxDroppedTargets` may result in increased memory usage if a big number of scrape targets are dropped during relabeling.
+
+* If `vmagent` scrapes a big number of targets then the `-promscrape.dropOriginalLabels` command-line option may be passed to `vmagent` in order to reduce memory usage.
+  This option drops `"discoveredLabels"` and `"droppedTargets"` lists at `/api/v1/targets` page, which may result in reduced debuggability for improperly configured per-target relabeling.
+
+* If `vmagent` scrapes targets with millions of metrics per target (for example, when scraping [federation endpoints](https://prometheus.io/docs/prometheus/latest/federation/)),
+  we recommend enabling [stream parsing mode](#stream-parsing-mode) in order to reduce memory usage during scraping.
+
+* We recommend you increase `-remoteWrite.queues` if `vmagent_remotewrite_pending_data_bytes` metric exported at `http://vmagent-host:8429/metrics` page grows constantly.
+
+* If you see gaps in the data pushed by `vmagent` to remote storage when `-remoteWrite.maxDiskUsagePerURL` is set, try increasing `-remoteWrite.queues`.
+  Such gaps may appear because `vmagent` cannot keep up with sending the collected data to remote storage. Therefore it starts dropping the buffered data
+  if the on-disk buffer size exceeds `-remoteWrite.maxDiskUsagePerURL`.
+
+* `vmagent` drops data blocks if remote storage replies with `400 Bad Request` and `409 Conflict` HTTP responses. The number of dropped blocks can be monitored via `vmagent_remotewrite_packets_dropped_total` metric exported at [/metrics page](#monitoring).
+
+* Use `-remoteWrite.queues=1` when `-remoteWrite.url` points to remote storage, which doesn't accept out-of-order samples (aka data backfilling). Such storage systems include Prometheus, Cortex and Thanos, which typically emit `out of order sample` errors. The best solution is to use remote storage with [backfilling support](https://docs.victoriametrics.com/#backfilling).
+
+* `vmagent` buffers scraped data at the `-remoteWrite.tmpDataPath` directory until it is sent to `-remoteWrite.url`.
+  The directory can grow large when remote storage is unavailable for extended periods of time and if `-remoteWrite.maxDiskUsagePerURL` isn't set.
+  If you don't want to send all the data from the directory to remote storage then simply stop `vmagent` and delete the directory.
+
+* By default `vmagent` masks `-remoteWrite.url` with `secret-url` values in logs and at `/metrics` page because
+  the url may contain sensitive information such as auth tokens or passwords.
+  Pass `-remoteWrite.showURL` command-line flag when starting `vmagent` in order to see all the valid urls.
+
+* By default `vmagent` evenly spreads scrape load in time. If a particular scrape target must be scraped at the beginning of some interval,
+  then `scrape_align_interval` option  must be used. For example, the following config aligns hourly scrapes to the beginning of hour:
+
+  ```yml
+  scrape_configs:
+  - job_name: foo
+    scrape_interval: 1h
+    scrape_align_interval: 1h
+  ```
+
+* By default `vmagent` evenly spreads scrape load in time. If a particular scrape target must be scraped at specific offset, then `scrape_offset` option must be used.
+  For example, the following config instructs `vmagent` to scrape the target at 10 seconds of every minute:
+
+  ```yml
+  scrape_configs:
+  - job_name: foo
+    scrape_interval: 1m
+    scrape_offset: 10s
+  ```
+
+* If you see `skipping duplicate scrape target with identical labels` errors when scraping Kubernetes pods, then it is likely these pods listen to multiple ports
+  or they use an init container. These errors can either be fixed or suppressed with the `-promscrape.suppressDuplicateScrapeTargetErrors` command-line flag.
+  See the available options below if you prefer fixing the root cause of the error:
+
+  The following relabeling rule may be added to `relabel_configs` section in order to filter out pods with unneeded ports:
+  ```yml
+  - action: keep_if_equal
+    source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_port, __meta_kubernetes_pod_container_port_number]
+  ```
+
+  The following relabeling rule may be added to `relabel_configs` section in order to filter out init container pods:
+  ```yml
+  - action: drop
+    source_labels: [__meta_kubernetes_pod_container_init]
+    regex: true
+  ```
+
+## Kafka integration
+
+[Enterprise version](https://victoriametrics.com/enterprise.html) of `vmagent` can read and write metrics from / to Kafka:
+
+* [Reading metrics from Kafka](#reading-metrics-from-kafka)
+* [Writing metrics to Kafka](#writing-metrics-to-kafka)
+
+The enterprise version of vmagent is available for evaluation at [releases](https://github.com/VictoriaMetrics/VictoriaMetrics/releases) page in `vmutils-*-enteprise.tar.gz` archives and in [docker images](https://hub.docker.com/r/victoriametrics/vmagent/tags) with tags containing `enterprise` suffix.
+
+
+### Reading metrics from Kafka
+
+[Enterprise version](https://victoriametrics.com/enterprise.html) of `vmagent` can read metrics in various formats from Kafka messages. These formats can be configured with `-kafka.consumer.topic.defaultFormat` or `-kafka.consumer.topic.format` command-line options. The following formats are supported:
+
+* `promremotewrite` - [Prometheus remote_write](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#remote_write). Messages in this format can be sent by vmagent - see [these docs](#writing-metrics-to-kafka).
+* `influx` - [InfluxDB line protocol format](https://docs.influxdata.com/influxdb/v1.7/write_protocols/line_protocol_tutorial/).
+* `prometheus` - [Prometheus text exposition format](https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md#text-based-format) and [OpenMetrics format](https://github.com/OpenObservability/OpenMetrics/blob/master/specification/OpenMetrics.md).
+* `graphite` - [Graphite plaintext format](https://graphite.readthedocs.io/en/latest/feeding-carbon.html#the-plaintext-protocol).
+* `jsonline` - [JSON line format](https://docs.victoriametrics.com/#how-to-import-data-in-json-line-format).
+
+Every Kafka message may contain multiple lines in `influx`, `prometheus`, `graphite` and `jsonline` format delimited by `\n`.
+
+`vmagent` consumes messages from Kafka topics specified by `-kafka.consumer.topic` command-line flag. Multiple topics can be specified by passing multiple `-kafka.consumer.topic` command-line flags to `vmagent`.
+
+`vmagent` consumes messages from Kafka brokers specified by `-kafka.consumer.topic.brokers` command-line flag. Multiple brokers can be specified per each `-kafka.consumer.topic` by passing a list of brokers delimited by `;`. For example, `-kafka.consumer.topic.brokers=host1:9092;host2:9092`.
+
+The following command starts `vmagent`, which reads metrics in InfluxDB line protocol format from Kafka broker at `localhost:9092` from the topic `metrics-by-telegraf` and sends them to remote storage at `http://localhost:8428/api/v1/write`:
+
+```bash
+./bin/vmagent -remoteWrite.url=http://localhost:8428/api/v1/write \
+       -kafka.consumer.topic.brokers=localhost:9092 \
+       -kafka.consumer.topic.format=influx \
+       -kafka.consumer.topic=metrics-by-telegraf \
+       -kafka.consumer.topic.groupID=some-id
+```
+
+It is expected that [Telegraf](https://github.com/influxdata/telegraf) sends metrics to the `metrics-by-telegraf` topic with the following config:
+
+```yaml
+[[outputs.kafka]]
+brokers = ["localhost:9092"]
+topic = "influx"
+data_format = "influx"
+```
+
+
+#### Command-line flags for Kafka consumer
+
+These command-line flags are available only in [enterprise](https://victoriametrics.com/enterprise.html) version of `vmagent`, which can be downloaded for evaluation from [releases](https://github.com/VictoriaMetrics/VictoriaMetrics/releases) page (see `vmutils-*-enteprise.tar.gz` archives) and from [docker images](https://hub.docker.com/r/victoriametrics/vmagent/tags) with tags containing `enterprise` suffix.
+
+```
+  -kafka.consumer.topic array
+        Kafka topic names for data consumption.
+        Supports an array of values separated by comma or specified via multiple flags.
+  -kafka.consumer.topic.basicAuth.password array
+        Optional basic auth password for -kafka.consumer.topic. Must be used in conjunction with any supported auth methods for kafka client, specified by flag -kafka.consumer.topic.options='security.protocol=SASL_SSL;sasl.mechanisms=PLAIN'
+        Supports an array of values separated by comma or specified via multiple flags.
+  -kafka.consumer.topic.basicAuth.username array
+        Optional basic auth username for -kafka.consumer.topic. Must be used in conjunction with any supported auth methods for kafka client, specified by flag -kafka.consumer.topic.options='security.protocol=SASL_SSL;sasl.mechanisms=PLAIN'
+        Supports an array of values separated by comma or specified via multiple flags.
+  -kafka.consumer.topic.brokers array
+        List of brokers to connect for given topic, e.g. -kafka.consumer.topic.broker=host-1:9092;host-2:9092
+        Supports an array of values separated by comma or specified via multiple flags.
+  -kafka.consumer.topic.defaultFormat string
+        Expected data format in the topic if -kafka.consumer.topic.format is skipped. (default "promremotewrite")
+  -kafka.consumer.topic.format array
+        data format for corresponding kafka topic. Valid formats: influx, prometheus, promremotewrite, graphite, jsonline
+        Supports an array of values separated by comma or specified via multiple flags.
+  -kafka.consumer.topic.groupID array
+        Defines group.id for topic
+        Supports an array of values separated by comma or specified via multiple flags.
+  -kafka.consumer.topic.isGzipped array
+        Enables gzip setting for topic messages payload. Only prometheus, jsonline and influx formats accept gzipped messages.
+        Supports array of values separated by comma or specified via multiple flags.
+  -kafka.consumer.topic.options array
+        Optional key=value;key1=value2 settings for topic consumer. See full configuration options at https://github.com/edenhill/librdkafka/blob/master/CONFIGURATION.md.
+        Supports an array of values separated by comma or specified via multiple flags.
+```
+
+### Writing metrics to Kafka
+
+[Enterprise version](https://victoriametrics.com/enterprise.html) of `vmagent` writes data to Kafka with `at-least-once` semantics if `-remoteWrite.url` contains e.g. Kafka url. For example, if `vmagent` is started with `-remoteWrite.url=kafka://localhost:9092/?topic=prom-rw`, then it would send Prometheus remote_write messages to Kafka bootstrap server at `localhost:9092` with the topic `prom-rw`. These messages can be read later from Kafka by another `vmagent` - see [these docs](#reading-metrics-from-kafka) for details.
+
+Additional Kafka options can be passed as query params to `-remoteWrite.url`. For instance, `kafka://localhost:9092/?topic=prom-rw&client.id=my-favorite-id` sets `client.id` Kafka option to `my-favorite-id`. The full list of Kafka options is available [here](https://github.com/edenhill/librdkafka/blob/master/CONFIGURATION.md).
+
+
+#### Kafka broker authorization and authentication
+
+Two types of auth are supported:
+
+* sasl with username and password:
+
+```bash
+./bin/vmagent -remoteWrite.url=kafka://localhost:9092/?topic=prom-rw&security.protocol=SASL_SSL&sasl.mechanisms=PLAIN -remoteWrite.basicAuth.username=user -remoteWrite.basicAuth.password=password
+```
+
+* tls certificates:
+
+```bash
+./bin/vmagent -remoteWrite.url=kafka://localhost:9092/?topic=prom-rw&security.protocol=SSL -remoteWrite.tlsCAFile=/opt/ca.pem -remoteWrite.tlsCertFile=/opt/cert.pem -remoteWrite.tlsKeyFile=/opt/key.pem
+```
+
+
+## How to build from sources
+
+We recommend using [binary releases](https://github.com/VictoriaMetrics/VictoriaMetrics/releases) - `vmagent` is located in the `vmutils-*` archives .
+
+
+### Development build
+
+1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.16.
+2. Run `make vmagent` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
+   It builds the `vmagent` binary and puts it into the `bin` folder.
+
+### Production build
+
+1. [Install docker](https://docs.docker.com/install/).
+2. Run `make vmagent-prod` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
+   It builds `vmagent-prod` binary and puts it into the `bin` folder.
+
+### Building docker images
+
+Run `make package-vmagent`. It builds `victoriametrics/vmagent:<PKG_TAG>` docker image locally.
+`<PKG_TAG>` is an auto-generated image tag, which depends on source code in [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
+The `<PKG_TAG>` may be manually set via `PKG_TAG=foobar make package-vmagent`.
+
+The base docker image is [alpine](https://hub.docker.com/_/alpine) but it is possible to use any other base image
+by setting it via `<ROOT_IMAGE>` environment variable. For example, the following command builds the image on top of [scratch](https://hub.docker.com/_/scratch) image:
+
+```bash
+ROOT_IMAGE=scratch make package-vmagent
+```
+
+### ARM build
+
+ARM build may run on Raspberry Pi or on [energy-efficient ARM servers](https://blog.cloudflare.com/arm-takes-wing/).
+
+### Development ARM build
+
+1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.16.
+2. Run `make vmagent-arm` or `make vmagent-arm64` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics)
+   It builds `vmagent-arm` or `vmagent-arm64` binary respectively and puts it into the `bin` folder.
+
+### Production ARM build
+
+1. [Install docker](https://docs.docker.com/install/).
+2. Run `make vmagent-arm-prod` or `make vmagent-arm64-prod` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
+   It builds `vmagent-arm-prod` or `vmagent-arm64-prod` binary respectively and puts it into the `bin` folder.
+
+
+## Profiling
+
+`vmagent` provides handlers for collecting the following [Go profiles](https://blog.golang.org/profiling-go-programs):
+
+* Memory profile can be collected with the following command:
+
+```bash
+curl -s http://<vmagent-host>:8429/debug/pprof/heap > mem.pprof
+```
+
+* CPU profile can be collected with the following command:
+
+```bash
+curl -s http://<vmagent-host>:8429/debug/pprof/profile > cpu.pprof
+```
+
+The command for collecting CPU profile waits for 30 seconds before returning.
+
+The collected profiles may be analyzed with [go tool pprof](https://github.com/google/pprof).
+
+
+## Advanced usage
+
+`vmagent` can be fine-tuned with various command-line flags. Run `./vmagent -help` in order to see the full list of these flags with their desciptions and default values:
+
+```
+./vmagent -help
+
+vmagent collects metrics data via popular data ingestion protocols and routes them to VictoriaMetrics.
+
+See the docs at https://docs.victoriametrics.com/vmagent.html .
+
+  -csvTrimTimestamp duration
+    	Trim timestamps when importing csv data to this duration. Minimum practical duration is 1ms. Higher duration (i.e. 1s) may be used for reducing disk space usage for timestamp data (default 1ms)
+  -dryRun
+    	Whether to check only config files without running vmagent. The following files are checked: -promscrape.config, -remoteWrite.relabelConfig, -remoteWrite.urlRelabelConfig . Unknown config entries are allowed in -promscrape.config by default. This can be changed with -promscrape.config.strictParse
+  -enableTCP6
+    	Whether to enable IPv6 for listening and dialing. By default only IPv4 TCP and UDP is used
+  -envflag.enable
+    	Whether to enable reading flags from environment variables additionally to command line. Command line flag values have priority over values from environment vars. Flags are read only from command line if this flag isn't set. See https://docs.victoriametrics.com/#environment-variables for more details
+  -envflag.prefix string
+    	Prefix for environment variables if -envflag.enable is set
+  -fs.disableMmap
+    	Whether to use pread() instead of mmap() for reading data files. By default mmap() is used for 64-bit arches and pread() is used for 32-bit arches, since they cannot read data files bigger than 2^32 bytes in memory. mmap() is usually faster for reading small data chunks than pread()
+  -graphiteListenAddr string
+    	TCP and UDP address to listen for Graphite plaintext data. Usually :2003 must be set. Doesn't work if empty
+  -graphiteTrimTimestamp duration
+    	Trim timestamps for Graphite data to this duration. Minimum practical duration is 1s. Higher duration (i.e. 1m) may be used for reducing disk space usage for timestamp data (default 1s)
+  -http.connTimeout duration
+    	Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem (default 2m0s)
+  -http.disableResponseCompression
+    	Disable compression of HTTP responses to save CPU resources. By default compression is enabled to save network bandwidth
+  -http.idleConnTimeout duration
+    	Timeout for incoming idle http connections (default 1m0s)
+  -http.maxGracefulShutdownDuration duration
+    	The maximum duration for a graceful shutdown of the HTTP server. A highly loaded server may require increased value for a graceful shutdown (default 7s)
+  -http.pathPrefix string
+    	An optional prefix to add to all the paths handled by http server. For example, if '-http.pathPrefix=/foo/bar' is set, then all the http requests will be handled on '/foo/bar/*' paths. This may be useful for proxied requests. See https://www.robustperception.io/using-external-urls-and-proxies-with-prometheus
+  -http.shutdownDelay duration
+    	Optional delay before http server shutdown. During this delay, the server returns non-OK responses from /health page, so load balancers can route new requests to other servers
+  -httpAuth.password string
+    	Password for HTTP Basic Auth. The authentication is disabled if -httpAuth.username is empty
+  -httpAuth.username string
+    	Username for HTTP Basic Auth. The authentication is disabled if empty. See also -httpAuth.password
+  -httpListenAddr string
+    	TCP address to listen for http connections. Set this flag to empty value in order to disable listening on any port. This mode may be useful for running multiple vmagent instances on the same server. Note that /targets and /metrics pages aren't available if -httpListenAddr='' (default ":8429")
+  -import.maxLineLen size
+    	The maximum length in bytes of a single line accepted by /api/v1/import; the line length can be limited with 'max_rows_per_line' query arg passed to /api/v1/export
+    	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 104857600)
+  -influx.databaseNames array
+    	Comma-separated list of database names to return from /query and /influx/query API. This can be needed for accepting data from Telegraf plugins such as https://github.com/fangli/fluent-plugin-influxdb
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -influx.maxLineSize size
+    	The maximum size in bytes for a single InfluxDB line during parsing
+    	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 262144)
+  -influxListenAddr string
+    	TCP and UDP address to listen for InfluxDB line protocol data. Usually :8189 must be set. Doesn't work if empty. This flag isn't needed when ingesting data over HTTP - just send it to http://<vmagent>:8429/write
+  -influxMeasurementFieldSeparator string
+    	Separator for '{measurement}{separator}{field_name}' metric name when inserted via InfluxDB line protocol (default "_")
+  -influxSkipMeasurement
+    	Uses '{field_name}' as a metric name while ignoring '{measurement}' and '-influxMeasurementFieldSeparator'
+  -influxSkipSingleField
+    	Uses '{measurement}' instead of '{measurement}{separator}{field_name}' for metic name if InfluxDB line contains only a single field
+  -influxTrimTimestamp duration
+    	Trim timestamps for InfluxDB line protocol data to this duration. Minimum practical duration is 1ms. Higher duration (i.e. 1s) may be used for reducing disk space usage for timestamp data (default 1ms)
+  -insert.maxQueueDuration duration
+    	The maximum duration for waiting in the queue for insert requests due to -maxConcurrentInserts (default 1m0s)
+  -loggerDisableTimestamps
+    	Whether to disable writing timestamps in logs
+  -loggerErrorsPerSecondLimit int
+    	Per-second limit on the number of ERROR messages. If more than the given number of errors are emitted per second, the remaining errors are suppressed. Zero values disable the rate limit
+  -loggerFormat string
+    	Format for logs. Possible values: default, json (default "default")
+  -loggerLevel string
+    	Minimum level of errors to log. Possible values: INFO, WARN, ERROR, FATAL, PANIC (default "INFO")
+  -loggerOutput string
+    	Output for the logs. Supported values: stderr, stdout (default "stderr")
+  -loggerTimezone string
+    	Timezone to use for timestamps in logs. Timezone must be a valid IANA Time Zone. For example: America/New_York, Europe/Berlin, Etc/GMT+3 or Local (default "UTC")
+  -loggerWarnsPerSecondLimit int
+    	Per-second limit on the number of WARN messages. If more than the given number of warns are emitted per second, then the remaining warns are suppressed. Zero values disable the rate limit
+  -maxConcurrentInserts int
+    	The maximum number of concurrent inserts. Default value should work for most cases, since it minimizes the overhead for concurrent inserts. This option is tigthly coupled with -insert.maxQueueDuration (default 16)
+  -maxInsertRequestSize size
+    	The maximum size in bytes of a single Prometheus remote_write API request
+    	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 33554432)
+  -memory.allowedBytes size
+    	Allowed size of system memory VictoriaMetrics caches may occupy. This option overrides -memory.allowedPercent if set to a non-zero value. Too low a value may increase the cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from OS page cache resulting in higher disk IO usage
+    	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 0)
+  -memory.allowedPercent float
+    	Allowed percent of system memory VictoriaMetrics caches may occupy. See also -memory.allowedBytes. Too low a value may increase cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from OS page cache which will result in higher disk IO usage (default 60)
+  -metricsAuthKey string
+    	Auth key for /metrics. It overrides httpAuth settings
+  -opentsdbHTTPListenAddr string
+    	TCP address to listen for OpentTSDB HTTP put requests. Usually :4242 must be set. Doesn't work if empty
+  -opentsdbListenAddr string
+    	TCP and UDP address to listen for OpentTSDB metrics. Telnet put messages and HTTP /api/put messages are simultaneously served on TCP port. Usually :4242 must be set. Doesn't work if empty
+  -opentsdbTrimTimestamp duration
+    	Trim timestamps for OpenTSDB 'telnet put' data to this duration. Minimum practical duration is 1s. Higher duration (i.e. 1m) may be used for reducing disk space usage for timestamp data (default 1s)
+  -opentsdbhttp.maxInsertRequestSize size
+    	The maximum size of OpenTSDB HTTP put request
+    	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 33554432)
+  -opentsdbhttpTrimTimestamp duration
+    	Trim timestamps for OpenTSDB HTTP data to this duration. Minimum practical duration is 1ms. Higher duration (i.e. 1s) may be used for reducing disk space usage for timestamp data (default 1ms)
+  -pprofAuthKey string
+    	Auth key for /debug/pprof. It overrides httpAuth settings
+  -promscrape.cluster.memberNum int
+    	The number of number in the cluster of scrapers. It must be an unique value in the range 0 ... promscrape.cluster.membersCount-1 across scrapers in the cluster
+  -promscrape.cluster.membersCount int
+    	The number of members in a cluster of scrapers. Each member must have an unique -promscrape.cluster.memberNum in the range 0 ... promscrape.cluster.membersCount-1 . Each member then scrapes roughly 1/N of all the targets. By default cluster scraping is disabled, i.e. a single scraper scrapes all the targets
+  -promscrape.cluster.replicationFactor int
+    	The number of members in the cluster, which scrape the same targets. If the replication factor is greater than 2, then the deduplication must be enabled at remote storage side. See https://docs.victoriametrics.com/#deduplication (default 1)
+  -promscrape.config string
+    	Optional path to Prometheus config file with 'scrape_configs' section containing targets to scrape. See https://docs.victoriametrics.com/#how-to-scrape-prometheus-exporters-such-as-node-exporter for details
+  -promscrape.config.dryRun
+    	Checks -promscrape.config file for errors and unsupported fields and then exits. Returns non-zero exit code on parsing errors and emits these errors to stderr. See also -promscrape.config.strictParse command-line flag. Pass -loggerLevel=ERROR if you don't need to see info messages in the output.
+  -promscrape.config.strictParse
+    	Whether to allow only supported fields in -promscrape.config . By default unsupported fields are silently skipped
+  -promscrape.configCheckInterval duration
+    	Interval for checking for changes in '-promscrape.config' file. By default the checking is disabled. Send SIGHUP signal in order to force config check for changes
+  -promscrape.consul.waitTime duration
+    	Wait time used by Consul service discovery. Default value is used if not set
+  -promscrape.consulSDCheckInterval duration
+    	Interval for checking for changes in Consul. This works only if consul_sd_configs is configured in '-promscrape.config' file. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#consul_sd_config for details (default 30s)
+  -promscrape.digitaloceanSDCheckInterval duration
+    	Interval for checking for changes in digital ocean. This works only if digitalocean_sd_configs is configured in '-promscrape.config' file. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#digitalocean_sd_config for details (default 1m0s)
+  -promscrape.disableCompression
+    	Whether to disable sending 'Accept-Encoding: gzip' request headers to all the scrape targets. This may reduce CPU usage on scrape targets at the cost of higher network bandwidth utilization. It is possible to set 'disable_compression: true' individually per each 'scrape_config' section in '-promscrape.config' for fine grained control
+  -promscrape.disableKeepAlive
+    	Whether to disable HTTP keep-alive connections when scraping all the targets. This may be useful when targets has no support for HTTP keep-alive connection. It is possible to set 'disable_keepalive: true' individually per each 'scrape_config' section in '-promscrape.config' for fine grained control. Note that disabling HTTP keep-alive may increase load on both vmagent and scrape targets
+  -promscrape.discovery.concurrency int
+    	The maximum number of concurrent requests to Prometheus autodiscovery API (Consul, Kubernetes, etc.) (default 100)
+  -promscrape.discovery.concurrentWaitTime duration
+    	The maximum duration for waiting to perform API requests if more than -promscrape.discovery.concurrency requests are simultaneously performed (default 1m0s)
+  -promscrape.dnsSDCheckInterval duration
+    	Interval for checking for changes in dns. This works only if dns_sd_configs is configured in '-promscrape.config' file. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#dns_sd_config for details (default 30s)
+  -promscrape.dockerSDCheckInterval duration
+    	Interval for checking for changes in docker. This works only if docker_sd_configs is configured in '-promscrape.config' file. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#docker_sd_config for details (default 30s)
+  -promscrape.dockerswarmSDCheckInterval duration
+    	Interval for checking for changes in dockerswarm. This works only if dockerswarm_sd_configs is configured in '-promscrape.config' file. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#dockerswarm_sd_config for details (default 30s)
+  -promscrape.dropOriginalLabels
+    	Whether to drop original labels for scrape targets at /targets and /api/v1/targets pages. This may be needed for reducing memory usage when original labels for big number of scrape targets occupy big amounts of memory. Note that this reduces debuggability for improper per-target relabeling configs
+  -promscrape.ec2SDCheckInterval duration
+    	Interval for checking for changes in ec2. This works only if ec2_sd_configs is configured in '-promscrape.config' file. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#ec2_sd_config for details (default 1m0s)
+  -promscrape.eurekaSDCheckInterval duration
+    	Interval for checking for changes in eureka. This works only if eureka_sd_configs is configured in '-promscrape.config' file. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#eureka_sd_config for details (default 30s)
+  -promscrape.fileSDCheckInterval duration
+    	Interval for checking for changes in 'file_sd_config'. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#file_sd_config for details (default 30s)
+  -promscrape.gceSDCheckInterval duration
+    	Interval for checking for changes in gce. This works only if gce_sd_configs is configured in '-promscrape.config' file. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#gce_sd_config for details (default 1m0s)
+  -promscrape.httpSDCheckInterval duration
+    	Interval for checking for changes in http endpoint service discovery. This works only if http_sd_configs is configured in '-promscrape.config' file. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#http_sd_config for details (default 1m0s)
+  -promscrape.kubernetes.apiServerTimeout duration
+    	How frequently to reload the full state from Kuberntes API server (default 30m0s)
+  -promscrape.kubernetesSDCheckInterval duration
+    	Interval for checking for changes in Kubernetes API server. This works only if kubernetes_sd_configs is configured in '-promscrape.config' file. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#kubernetes_sd_config for details (default 30s)
+  -promscrape.maxDroppedTargets int
+    	The maximum number of droppedTargets to show at /api/v1/targets page. Increase this value if your setup drops more scrape targets during relabeling and you need investigating labels for all the dropped targets. Note that the increased number of tracked dropped targets may result in increased memory usage (default 1000)
+  -promscrape.maxScrapeSize size
+    	The maximum size of scrape response in bytes to process from Prometheus targets. Bigger responses are rejected
+    	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 16777216)
+  -promscrape.noStaleMarkers
+    	Whether to disable sending Prometheus stale markers for metrics when scrape target disappears. This option may reduce memory usage if stale markers aren't needed for your setup. See also https://docs.victoriametrics.com/vmagent.html#stream-parsing-mode
+  -promscrape.openstackSDCheckInterval duration
+    	Interval for checking for changes in openstack API server. This works only if openstack_sd_configs is configured in '-promscrape.config' file. See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#openstack_sd_config for details (default 30s)
+  -promscrape.seriesLimitPerTarget int
+    	Optional limit on the number of unique time series a single scrape target can expose. See https://docs.victoriametrics.com/vmagent.html#cardinality-limiter for more info
+  -promscrape.streamParse
+    	Whether to enable stream parsing for metrics obtained from scrape targets. This may be useful for reducing memory usage when millions of metrics are exposed per each scrape target. It is posible to set 'stream_parse: true' individually per each 'scrape_config' section in '-promscrape.config' for fine grained control
+  -promscrape.suppressDuplicateScrapeTargetErrors
+    	Whether to suppress 'duplicate scrape target' errors; see https://docs.victoriametrics.com/vmagent.html#troubleshooting for details
+  -promscrape.suppressScrapeErrors
+    	Whether to suppress scrape errors logging. The last error for each target is always available at '/targets' page even if scrape errors logging is suppressed
+  -remoteWrite.basicAuth.password array
+    	Optional basic auth password to use for -remoteWrite.url. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.basicAuth.passwordFile array
+    	Optional path to basic auth password to use for -remoteWrite.url. The file is re-read every second. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.basicAuth.username array
+    	Optional basic auth username to use for -remoteWrite.url. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.bearerToken array
+    	Optional bearer auth token to use for -remoteWrite.url. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.bearerTokenFile array
+    	Optional path to bearer token file to use for -remoteWrite.url. The token is re-read from the file every second. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.flushInterval duration
+    	Interval for flushing the data to remote storage. This option takes effect only when less than 10K data points per second are pushed to -remoteWrite.url (default 1s)
+  -remoteWrite.label array
+    	Optional label in the form 'name=value' to add to all the metrics before sending them to -remoteWrite.url. Pass multiple -remoteWrite.label flags in order to add multiple labels to metrics before sending them to remote storage
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.maxBlockSize size
+    	The maximum size in bytes of unpacked request to send to remote storage. It shouldn't exceed -maxInsertRequestSize from VictoriaMetrics
+    	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 8388608)
+  -remoteWrite.maxDailySeries int
+    	The maximum number of unique series vmagent can send to remote storage systems during the last 24 hours. Excess series are logged and dropped. This can be useful for limiting series churn rate. See https://docs.victoriametrics.com/vmagent.html#cardinality-limiter
+  -remoteWrite.maxDiskUsagePerURL size
+    	The maximum file-based buffer size in bytes at -remoteWrite.tmpDataPath for each -remoteWrite.url. When buffer size reaches the configured maximum, then old data is dropped when adding new data to the buffer. Buffered data is stored in ~500MB chunks, so the minimum practical value for this flag is 500000000. Disk usage is unlimited if the value is set to 0
+    	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 0)
+  -remoteWrite.maxHourlySeries int
+    	The maximum number of unique series vmagent can send to remote storage systems during the last hour. Excess series are logged and dropped. This can be useful for limiting series cardinality. See https://docs.victoriametrics.com/vmagent.html#cardinality-limiter
+  -remoteWrite.multitenantURL array
+    	Base path for multitenant remote storage URL to write data to. See https://docs.victoriametrics.com/vmagent.html#multitenancy for details. Example url: http://<vminsert>:8480 . Pass multiple -remoteWrite.multitenantURL flags in order to replicate data to multiple remote storage systems. See also -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.oauth2.clientID array
+    	Optional OAuth2 clientID to use for -remoteWrite.url. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.oauth2.clientSecret array
+    	Optional OAuth2 clientSecret to use for -remoteWrite.url. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.oauth2.clientSecretFile array
+    	Optional OAuth2 clientSecretFile to use for -remoteWrite.url. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.oauth2.scopes array
+    	Optional OAuth2 scopes to use for -remoteWrite.url. Scopes must be delimited by ';'. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.oauth2.tokenUrl array
+    	Optional OAuth2 tokenURL to use for -remoteWrite.url. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.proxyURL array
+    	Optional proxy URL for writing data to -remoteWrite.url. Supported proxies: http, https, socks5. Example: -remoteWrite.proxyURL=socks5://proxy:1234
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.queues int
+    	The number of concurrent queues to each -remoteWrite.url. Set more queues if default number of queues isn't enough for sending high volume of collected data to remote storage. Default value is 2 * numberOfAvailableCPUs (default 8)
+  -remoteWrite.rateLimit array
+    	Optional rate limit in bytes per second for data sent to -remoteWrite.url. By default the rate limit is disabled. It can be useful for limiting load on remote storage when big amounts of buffered data is sent after temporary unavailability of the remote storage
+    	Supports array of values separated by comma or specified via multiple flags.
+  -remoteWrite.relabelConfig string
+    	Optional path to file with relabel_config entries. These entries are applied to all the metrics before sending them to -remoteWrite.url. See https://docs.victoriametrics.com/vmagent.html#relabeling for details
+  -remoteWrite.relabelDebug
+    	Whether to log metrics before and after relabeling with -remoteWrite.relabelConfig. If the -remoteWrite.relabelDebug is enabled, then the metrics aren't sent to remote storage. This is useful for debugging the relabeling configs
+  -remoteWrite.roundDigits array
+    	Round metric values to this number of decimal digits after the point before writing them to remote storage. Examples: -remoteWrite.roundDigits=2 would round 1.236 to 1.24, while -remoteWrite.roundDigits=-1 would round 126.78 to 130. By default digits rounding is disabled. Set it to 100 for disabling it for a particular remote storage. This option may be used for improving data compression for the stored metrics
+    	Supports array of values separated by comma or specified via multiple flags.
+  -remoteWrite.sendTimeout array
+    	Timeout for sending a single block of data to -remoteWrite.url
+    	Supports array of values separated by comma or specified via multiple flags.
+  -remoteWrite.showURL
+    	Whether to show -remoteWrite.url in the exported metrics. It is hidden by default, since it can contain sensitive info such as auth key
+  -remoteWrite.significantFigures array
+    	The number of significant figures to leave in metric values before writing them to remote storage. See https://en.wikipedia.org/wiki/Significant_figures . Zero value saves all the significant figures. This option may be used for improving data compression for the stored metrics. See also -remoteWrite.roundDigits
+    	Supports array of values separated by comma or specified via multiple flags.
+  -remoteWrite.tlsCAFile array
+    	Optional path to TLS CA file to use for verifying connections to -remoteWrite.url. By default system CA is used. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.tlsCertFile array
+    	Optional path to client-side TLS certificate file to use when connecting to -remoteWrite.url. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.tlsInsecureSkipVerify array
+    	Whether to skip tls verification when connecting to -remoteWrite.url
+    	Supports array of values separated by comma or specified via multiple flags.
+  -remoteWrite.tlsKeyFile array
+    	Optional path to client-side TLS certificate key to use when connecting to -remoteWrite.url. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.tlsServerName array
+    	Optional TLS server name to use for connections to -remoteWrite.url. By default the server name from -remoteWrite.url is used. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.tmpDataPath string
+    	Path to directory where temporary data for remote write component is stored. See also -remoteWrite.maxDiskUsagePerURL (default "vmagent-remotewrite-data")
+  -remoteWrite.url array
+    	Remote storage URL to write data to. It must support Prometheus remote_write API. It is recommended using VictoriaMetrics as remote storage. Example url: http://<victoriametrics-host>:8428/api/v1/write . Pass multiple -remoteWrite.url flags in order to replicate data to multiple remote storage systems. See also -remoteWrite.multitenantURL
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.urlRelabelConfig array
+    	Optional path to relabel config for the corresponding -remoteWrite.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -remoteWrite.urlRelabelDebug array
+    	Whether to log metrics before and after relabeling with -remoteWrite.urlRelabelConfig. If the -remoteWrite.urlRelabelDebug is enabled, then the metrics aren't sent to the corresponding -remoteWrite.url. This is useful for debugging the relabeling configs
+    	Supports array of values separated by comma or specified via multiple flags.
+  -sortLabels
+    	Whether to sort labels for incoming samples before writing them to all the configured remote storage systems. This may be needed for reducing memory usage at remote storage when the order of labels in incoming samples is random. For example, if m{k1="v1",k2="v2"} may be sent as m{k2="v2",k1="v1"}Enabled sorting for labels can slow down ingestion performance a bit
+  -tls
+    	Whether to enable TLS (aka HTTPS) for incoming requests. -tlsCertFile and -tlsKeyFile must be set if -tls is set
+  -tlsCertFile string
+    	Path to file with TLS certificate. Used only if -tls is set. Prefer ECDSA certs instead of RSA certs as RSA certs are slower
+  -tlsKeyFile string
+    	Path to file with TLS key. Used only if -tls is set
+  -version
+    	Show VictoriaMetrics version
+```

app/vmagent/common/push_ctx.go

@@ -0,0 +1,66 @@
+package common
+
+import (
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promrelabel"
+)
+
+// PushCtx is a context used for populating WriteRequest.
+type PushCtx struct {
+	WriteRequest prompbmarshal.WriteRequest
+
+	// Labels contains flat list of all the labels used in WriteRequest.
+	Labels []prompbmarshal.Label
+
+	// Samples contains flat list of all the samples used in WriteRequest.
+	Samples []prompbmarshal.Sample
+}
+
+// Reset resets ctx.
+func (ctx *PushCtx) Reset() {
+	tss := ctx.WriteRequest.Timeseries
+	for i := range tss {
+		ts := &tss[i]
+		ts.Labels = nil
+		ts.Samples = nil
+	}
+	ctx.WriteRequest.Timeseries = ctx.WriteRequest.Timeseries[:0]
+
+	promrelabel.CleanLabels(ctx.Labels)
+	ctx.Labels = ctx.Labels[:0]
+
+	ctx.Samples = ctx.Samples[:0]
+}
+
+// GetPushCtx returns PushCtx from pool.
+//
+// Call PutPushCtx when the ctx is no longer needed.
+func GetPushCtx() *PushCtx {
+	select {
+	case ctx := <-pushCtxPoolCh:
+		return ctx
+	default:
+		if v := pushCtxPool.Get(); v != nil {
+			return v.(*PushCtx)
+		}
+		return &PushCtx{}
+	}
+}
+
+// PutPushCtx returns ctx to the pool.
+//
+// ctx mustn't be used after returning to the pool.
+func PutPushCtx(ctx *PushCtx) {
+	ctx.Reset()
+	select {
+	case pushCtxPoolCh <- ctx:
+	default:
+		pushCtxPool.Put(ctx)
+	}
+}
+
+var pushCtxPool sync.Pool
+var pushCtxPoolCh = make(chan *PushCtx, cgroup.AvailableCPUs())

app/vmagent/csvimport/request_handler.go

@@ -0,0 +1,77 @@
+package csvimport
+
+import (
+	"net/http"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	parserCommon "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
+	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/csvimport"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/tenantmetrics"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted       = metrics.NewCounter(`vmagent_rows_inserted_total{type="csvimport"}`)
+	rowsTenantInserted = tenantmetrics.NewCounterMap(`vmagent_tenant_inserted_rows_total{type="csvimport"}`)
+	rowsPerInsert      = metrics.NewHistogram(`vmagent_rows_per_insert{type="csvimport"}`)
+)
+
+// InsertHandler processes csv data from req.
+func InsertHandler(at *auth.Token, req *http.Request) error {
+	extraLabels, err := parserCommon.GetExtraLabels(req)
+	if err != nil {
+		return err
+	}
+	return writeconcurrencylimiter.Do(func() error {
+		return parser.ParseStream(req, func(rows []parser.Row) error {
+			return insertRows(at, rows, extraLabels)
+		})
+	})
+}
+
+func insertRows(at *auth.Token, rows []parser.Row, extraLabels []prompbmarshal.Label) error {
+	ctx := common.GetPushCtx()
+	defer common.PutPushCtx(ctx)
+
+	tssDst := ctx.WriteRequest.Timeseries[:0]
+	labels := ctx.Labels[:0]
+	samples := ctx.Samples[:0]
+	for i := range rows {
+		r := &rows[i]
+		labelsLen := len(labels)
+		labels = append(labels, prompbmarshal.Label{
+			Name:  "__name__",
+			Value: r.Metric,
+		})
+		for j := range r.Tags {
+			tag := &r.Tags[j]
+			labels = append(labels, prompbmarshal.Label{
+				Name:  tag.Key,
+				Value: tag.Value,
+			})
+		}
+		labels = append(labels, extraLabels...)
+		samples = append(samples, prompbmarshal.Sample{
+			Value:     r.Value,
+			Timestamp: r.Timestamp,
+		})
+		tssDst = append(tssDst, prompbmarshal.TimeSeries{
+			Labels:  labels[labelsLen:],
+			Samples: samples[len(samples)-1:],
+		})
+	}
+	ctx.WriteRequest.Timeseries = tssDst
+	ctx.Labels = labels
+	ctx.Samples = samples
+	remotewrite.PushWithAuthToken(at, &ctx.WriteRequest)
+	rowsInserted.Add(len(rows))
+	if at != nil {
+		rowsTenantInserted.Get(at).Add(len(rows))
+	}
+	rowsPerInsert.Update(float64(len(rows)))
+	return nil
+}

app/vmagent/datadog/request_handler.go

@@ -0,0 +1,99 @@
+package datadog
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	parserCommon "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
+	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/datadog"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/tenantmetrics"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted       = metrics.NewCounter(`vmagent_rows_inserted_total{type="datadog"}`)
+	rowsTenantInserted = tenantmetrics.NewCounterMap(`vmagent_tenant_inserted_rows_total{type="datadog"}`)
+	rowsPerInsert      = metrics.NewHistogram(`vmagent_rows_per_insert{type="datadog"}`)
+)
+
+// InsertHandlerForHTTP processes remote write for DataDog POST /api/v1/series request.
+//
+// See https://docs.datadoghq.com/api/latest/metrics/#submit-metrics
+func InsertHandlerForHTTP(at *auth.Token, req *http.Request) error {
+	extraLabels, err := parserCommon.GetExtraLabels(req)
+	if err != nil {
+		return err
+	}
+	return writeconcurrencylimiter.Do(func() error {
+		ce := req.Header.Get("Content-Encoding")
+		return parser.ParseStream(req.Body, ce, func(series []parser.Series) error {
+			return insertRows(at, series, extraLabels)
+		})
+	})
+}
+
+func insertRows(at *auth.Token, series []parser.Series, extraLabels []prompbmarshal.Label) error {
+	ctx := common.GetPushCtx()
+	defer common.PutPushCtx(ctx)
+
+	rowsTotal := 0
+	tssDst := ctx.WriteRequest.Timeseries[:0]
+	labels := ctx.Labels[:0]
+	samples := ctx.Samples[:0]
+	for i := range series {
+		ss := &series[i]
+		rowsTotal += len(ss.Points)
+		labelsLen := len(labels)
+		labels = append(labels, prompbmarshal.Label{
+			Name:  "__name__",
+			Value: ss.Metric,
+		})
+		labels = append(labels, prompbmarshal.Label{
+			Name:  "host",
+			Value: ss.Host,
+		})
+		for _, tag := range ss.Tags {
+			n := strings.IndexByte(tag, ':')
+			if n < 0 {
+				return fmt.Errorf("cannot find ':' in tag %q", tag)
+			}
+			name := tag[:n]
+			value := tag[n+1:]
+			if name == "host" {
+				name = "exported_host"
+			}
+			labels = append(labels, prompbmarshal.Label{
+				Name:  name,
+				Value: value,
+			})
+		}
+		labels = append(labels, extraLabels...)
+		samplesLen := len(samples)
+		for _, pt := range ss.Points {
+			samples = append(samples, prompbmarshal.Sample{
+				Timestamp: pt.Timestamp(),
+				Value:     pt.Value(),
+			})
+		}
+		tssDst = append(tssDst, prompbmarshal.TimeSeries{
+			Labels:  labels[labelsLen:],
+			Samples: samples[samplesLen:],
+		})
+	}
+	ctx.WriteRequest.Timeseries = tssDst
+	ctx.Labels = labels
+	ctx.Samples = samples
+	remotewrite.PushWithAuthToken(at, &ctx.WriteRequest)
+	rowsInserted.Add(rowsTotal)
+	if at != nil {
+		rowsTenantInserted.Get(at).Add(rowsTotal)
+	}
+	rowsPerInsert.Update(float64(rowsTotal))
+	return nil
+}

app/vmagent/deployment/Dockerfile

@@ -0,0 +1,8 @@
+ARG base_image
+FROM $base_image
+
+EXPOSE 8429
+
+ENTRYPOINT ["/vmagent-prod"]
+ARG src_binary
+COPY $src_binary ./vmagent-prod

app/vmagent/graphite/request_handler.go

@@ -0,0 +1,65 @@
+package graphite
+
+import (
+	"io"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/graphite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted  = metrics.NewCounter(`vmagent_rows_inserted_total{type="graphite"}`)
+	rowsPerInsert = metrics.NewHistogram(`vmagent_rows_per_insert{type="graphite"}`)
+)
+
+// InsertHandler processes remote write for graphite plaintext protocol.
+//
+// See https://graphite.readthedocs.io/en/latest/feeding-carbon.html#the-plaintext-protocol
+func InsertHandler(r io.Reader) error {
+	return writeconcurrencylimiter.Do(func() error {
+		return parser.ParseStream(r, insertRows)
+	})
+}
+
+func insertRows(rows []parser.Row) error {
+	ctx := common.GetPushCtx()
+	defer common.PutPushCtx(ctx)
+
+	tssDst := ctx.WriteRequest.Timeseries[:0]
+	labels := ctx.Labels[:0]
+	samples := ctx.Samples[:0]
+	for i := range rows {
+		r := &rows[i]
+		labelsLen := len(labels)
+		labels = append(labels, prompbmarshal.Label{
+			Name:  "__name__",
+			Value: r.Metric,
+		})
+		for j := range r.Tags {
+			tag := &r.Tags[j]
+			labels = append(labels, prompbmarshal.Label{
+				Name:  tag.Key,
+				Value: tag.Value,
+			})
+		}
+		samples = append(samples, prompbmarshal.Sample{
+			Value:     r.Value,
+			Timestamp: r.Timestamp,
+		})
+		tssDst = append(tssDst, prompbmarshal.TimeSeries{
+			Labels:  labels[labelsLen:],
+			Samples: samples[len(samples)-1:],
+		})
+	}
+	ctx.WriteRequest.Timeseries = tssDst
+	ctx.Labels = labels
+	ctx.Samples = samples
+	remotewrite.Push(&ctx.WriteRequest)
+	rowsInserted.Add(len(rows))
+	rowsPerInsert.Update(float64(len(rows)))
+	return nil
+}

app/vmagent/influx/request_handler.go

@@ -0,0 +1,185 @@
+package influx
+
+import (
+	"flag"
+	"io"
+	"net/http"
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promrelabel"
+	parserCommon "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
+	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/influx"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/tenantmetrics"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	measurementFieldSeparator = flag.String("influxMeasurementFieldSeparator", "_", "Separator for '{measurement}{separator}{field_name}' metric name when inserted via InfluxDB line protocol")
+	skipSingleField           = flag.Bool("influxSkipSingleField", false, "Uses '{measurement}' instead of '{measurement}{separator}{field_name}' for metic name if InfluxDB line contains only a single field")
+	skipMeasurement           = flag.Bool("influxSkipMeasurement", false, "Uses '{field_name}' as a metric name while ignoring '{measurement}' and '-influxMeasurementFieldSeparator'")
+)
+
+var (
+	rowsInserted       = metrics.NewCounter(`vmagent_rows_inserted_total{type="influx"}`)
+	rowsTenantInserted = tenantmetrics.NewCounterMap(`vmagent_tenant_inserted_rows_total{type="influx"}`)
+	rowsPerInsert      = metrics.NewHistogram(`vmagent_rows_per_insert{type="influx"}`)
+)
+
+// InsertHandlerForReader processes remote write for influx line protocol.
+//
+// See https://github.com/influxdata/telegraf/tree/master/plugins/inputs/socket_listener/
+func InsertHandlerForReader(r io.Reader, isGzipped bool) error {
+	return writeconcurrencylimiter.Do(func() error {
+		return parser.ParseStream(r, isGzipped, "", "", func(db string, rows []parser.Row) error {
+			return insertRows(nil, db, rows, nil)
+		})
+	})
+}
+
+// InsertHandlerForHTTP processes remote write for influx line protocol.
+//
+// See https://github.com/influxdata/influxdb/blob/4cbdc197b8117fee648d62e2e5be75c6575352f0/tsdb/README.md
+func InsertHandlerForHTTP(at *auth.Token, req *http.Request) error {
+	extraLabels, err := parserCommon.GetExtraLabels(req)
+	if err != nil {
+		return err
+	}
+	return writeconcurrencylimiter.Do(func() error {
+		isGzipped := req.Header.Get("Content-Encoding") == "gzip"
+		q := req.URL.Query()
+		precision := q.Get("precision")
+		// Read db tag from https://docs.influxdata.com/influxdb/v1.7/tools/api/#write-http-endpoint
+		db := q.Get("db")
+		return parser.ParseStream(req.Body, isGzipped, precision, db, func(db string, rows []parser.Row) error {
+			return insertRows(at, db, rows, extraLabels)
+		})
+	})
+}
+
+func insertRows(at *auth.Token, db string, rows []parser.Row, extraLabels []prompbmarshal.Label) error {
+	ctx := getPushCtx()
+	defer putPushCtx(ctx)
+
+	rowsTotal := 0
+	tssDst := ctx.ctx.WriteRequest.Timeseries[:0]
+	labels := ctx.ctx.Labels[:0]
+	samples := ctx.ctx.Samples[:0]
+	commonLabels := ctx.commonLabels[:0]
+	buf := ctx.buf[:0]
+	for i := range rows {
+		r := &rows[i]
+		rowsTotal += len(r.Fields)
+		commonLabels = commonLabels[:0]
+		hasDBKey := false
+		for j := range r.Tags {
+			tag := &r.Tags[j]
+			if tag.Key == "db" {
+				hasDBKey = true
+			}
+			commonLabels = append(commonLabels, prompbmarshal.Label{
+				Name:  tag.Key,
+				Value: tag.Value,
+			})
+		}
+		if len(db) > 0 && !hasDBKey {
+			commonLabels = append(commonLabels, prompbmarshal.Label{
+				Name:  "db",
+				Value: db,
+			})
+		}
+		commonLabels = append(commonLabels, extraLabels...)
+		ctx.metricGroupBuf = ctx.metricGroupBuf[:0]
+		if !*skipMeasurement {
+			ctx.metricGroupBuf = append(ctx.metricGroupBuf, r.Measurement...)
+		}
+		// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1139
+		skipFieldKey := len(r.Measurement) > 0 && len(r.Fields) == 1 && *skipSingleField
+		if len(ctx.metricGroupBuf) > 0 && !skipFieldKey {
+			ctx.metricGroupBuf = append(ctx.metricGroupBuf, *measurementFieldSeparator...)
+		}
+		for j := range r.Fields {
+			f := &r.Fields[j]
+			bufLen := len(buf)
+			buf = append(buf, ctx.metricGroupBuf...)
+			if !skipFieldKey {
+				buf = append(buf, f.Key...)
+			}
+			metricGroup := bytesutil.ToUnsafeString(buf[bufLen:])
+			labelsLen := len(labels)
+			labels = append(labels, prompbmarshal.Label{
+				Name:  "__name__",
+				Value: metricGroup,
+			})
+			labels = append(labels, commonLabels...)
+			samples = append(samples, prompbmarshal.Sample{
+				Timestamp: r.Timestamp,
+				Value:     f.Value,
+			})
+			tssDst = append(tssDst, prompbmarshal.TimeSeries{
+				Labels:  labels[labelsLen:],
+				Samples: samples[len(samples)-1:],
+			})
+		}
+	}
+	ctx.buf = buf
+	ctx.ctx.WriteRequest.Timeseries = tssDst
+	ctx.ctx.Labels = labels
+	ctx.ctx.Samples = samples
+	ctx.commonLabels = commonLabels
+	remotewrite.PushWithAuthToken(at, &ctx.ctx.WriteRequest)
+	rowsInserted.Add(rowsTotal)
+	if at != nil {
+		rowsTenantInserted.Get(at).Add(rowsTotal)
+	}
+	rowsPerInsert.Update(float64(rowsTotal))
+
+	return nil
+}
+
+type pushCtx struct {
+	ctx            common.PushCtx
+	commonLabels   []prompbmarshal.Label
+	metricGroupBuf []byte
+	buf            []byte
+}
+
+func (ctx *pushCtx) reset() {
+	ctx.ctx.Reset()
+
+	promrelabel.CleanLabels(ctx.commonLabels)
+	ctx.commonLabels = ctx.commonLabels[:0]
+
+	ctx.metricGroupBuf = ctx.metricGroupBuf[:0]
+	ctx.buf = ctx.buf[:0]
+}
+
+func getPushCtx() *pushCtx {
+	select {
+	case ctx := <-pushCtxPoolCh:
+		return ctx
+	default:
+		if v := pushCtxPool.Get(); v != nil {
+			return v.(*pushCtx)
+		}
+		return &pushCtx{}
+	}
+}
+
+func putPushCtx(ctx *pushCtx) {
+	ctx.reset()
+	select {
+	case pushCtxPoolCh <- ctx:
+	default:
+		pushCtxPool.Put(ctx)
+	}
+}
+
+var pushCtxPool sync.Pool
+var pushCtxPoolCh = make(chan *pushCtx, cgroup.AvailableCPUs())

app/vmagent/main.go

@@ -0,0 +1,440 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"strings"
+	"sync/atomic"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/csvimport"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/datadog"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/graphite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/influx"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/native"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/opentsdb"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/opentsdbhttp"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/prometheusimport"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/promremotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/vmimport"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/buildinfo"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envflag"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/influxutils"
+	graphiteserver "github.com/VictoriaMetrics/VictoriaMetrics/lib/ingestserver/graphite"
+	influxserver "github.com/VictoriaMetrics/VictoriaMetrics/lib/ingestserver/influx"
+	opentsdbserver "github.com/VictoriaMetrics/VictoriaMetrics/lib/ingestserver/opentsdb"
+	opentsdbhttpserver "github.com/VictoriaMetrics/VictoriaMetrics/lib/ingestserver/opentsdbhttp"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promscrape"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	httpListenAddr = flag.String("httpListenAddr", ":8429", "TCP address to listen for http connections. "+
+		"Set this flag to empty value in order to disable listening on any port. This mode may be useful for running multiple vmagent instances on the same server. "+
+		"Note that /targets and /metrics pages aren't available if -httpListenAddr=''")
+	influxListenAddr = flag.String("influxListenAddr", "", "TCP and UDP address to listen for InfluxDB line protocol data. Usually :8189 must be set. Doesn't work if empty. "+
+		"This flag isn't needed when ingesting data over HTTP - just send it to http://<vmagent>:8429/write")
+	graphiteListenAddr = flag.String("graphiteListenAddr", "", "TCP and UDP address to listen for Graphite plaintext data. Usually :2003 must be set. Doesn't work if empty")
+	opentsdbListenAddr = flag.String("opentsdbListenAddr", "", "TCP and UDP address to listen for OpentTSDB metrics. "+
+		"Telnet put messages and HTTP /api/put messages are simultaneously served on TCP port. "+
+		"Usually :4242 must be set. Doesn't work if empty")
+	opentsdbHTTPListenAddr = flag.String("opentsdbHTTPListenAddr", "", "TCP address to listen for OpentTSDB HTTP put requests. Usually :4242 must be set. Doesn't work if empty")
+	dryRun                 = flag.Bool("dryRun", false, "Whether to check only config files without running vmagent. The following files are checked: "+
+		"-promscrape.config, -remoteWrite.relabelConfig, -remoteWrite.urlRelabelConfig . "+
+		"Unknown config entries are allowed in -promscrape.config by default. This can be changed with -promscrape.config.strictParse")
+)
+
+var (
+	influxServer       *influxserver.Server
+	graphiteServer     *graphiteserver.Server
+	opentsdbServer     *opentsdbserver.Server
+	opentsdbhttpServer *opentsdbhttpserver.Server
+)
+
+func main() {
+	// Write flags and help message to stdout, since it is easier to grep or pipe.
+	flag.CommandLine.SetOutput(os.Stdout)
+	flag.Usage = usage
+	envflag.Parse()
+	remotewrite.InitSecretFlags()
+	buildinfo.Init()
+	logger.Init()
+
+	if promscrape.IsDryRun() {
+		if err := promscrape.CheckConfig(); err != nil {
+			logger.Fatalf("error when checking -promscrape.config: %s", err)
+		}
+		logger.Infof("-promscrape.config is ok; exitting with 0 status code")
+		return
+	}
+	if *dryRun {
+		if err := remotewrite.CheckRelabelConfigs(); err != nil {
+			logger.Fatalf("error when checking relabel configs: %s", err)
+		}
+		if err := promscrape.CheckConfig(); err != nil {
+			logger.Fatalf("error when checking -promscrape.config: %s", err)
+		}
+		logger.Infof("all the configs are ok; exitting with 0 status code")
+		return
+	}
+
+	logger.Infof("starting vmagent at %q...", *httpListenAddr)
+	startTime := time.Now()
+	remotewrite.Init()
+	common.StartUnmarshalWorkers()
+	writeconcurrencylimiter.Init()
+	if len(*influxListenAddr) > 0 {
+		influxServer = influxserver.MustStart(*influxListenAddr, func(r io.Reader) error {
+			return influx.InsertHandlerForReader(r, false)
+		})
+	}
+	if len(*graphiteListenAddr) > 0 {
+		graphiteServer = graphiteserver.MustStart(*graphiteListenAddr, graphite.InsertHandler)
+	}
+	if len(*opentsdbListenAddr) > 0 {
+		opentsdbServer = opentsdbserver.MustStart(*opentsdbListenAddr, opentsdb.InsertHandler, opentsdbhttp.InsertHandler)
+	}
+	if len(*opentsdbHTTPListenAddr) > 0 {
+		opentsdbhttpServer = opentsdbhttpserver.MustStart(*opentsdbHTTPListenAddr, opentsdbhttp.InsertHandler)
+	}
+
+	promscrape.Init(remotewrite.Push)
+
+	if len(*httpListenAddr) > 0 {
+		go httpserver.Serve(*httpListenAddr, requestHandler)
+	}
+	logger.Infof("started vmagent in %.3f seconds", time.Since(startTime).Seconds())
+
+	sig := procutil.WaitForSigterm()
+	logger.Infof("received signal %s", sig)
+
+	startTime = time.Now()
+	if len(*httpListenAddr) > 0 {
+		logger.Infof("gracefully shutting down webservice at %q", *httpListenAddr)
+		if err := httpserver.Stop(*httpListenAddr); err != nil {
+			logger.Fatalf("cannot stop the webservice: %s", err)
+		}
+		logger.Infof("successfully shut down the webservice in %.3f seconds", time.Since(startTime).Seconds())
+	}
+
+	promscrape.Stop()
+
+	if len(*influxListenAddr) > 0 {
+		influxServer.MustStop()
+	}
+	if len(*graphiteListenAddr) > 0 {
+		graphiteServer.MustStop()
+	}
+	if len(*opentsdbListenAddr) > 0 {
+		opentsdbServer.MustStop()
+	}
+	if len(*opentsdbHTTPListenAddr) > 0 {
+		opentsdbhttpServer.MustStop()
+	}
+	common.StopUnmarshalWorkers()
+	remotewrite.Stop()
+
+	logger.Infof("successfully stopped vmagent in %.3f seconds", time.Since(startTime).Seconds())
+}
+
+func requestHandler(w http.ResponseWriter, r *http.Request) bool {
+	if r.URL.Path == "/" {
+		if r.Method != "GET" {
+			return false
+		}
+		fmt.Fprintf(w, "<h2>vmagent</h2>")
+		fmt.Fprintf(w, "See docs at <a href='https://docs.victoriametrics.com/vmagent.html'>https://docs.victoriametrics.com/vmagent.html</a></br>")
+		fmt.Fprintf(w, "Useful endpoints:</br>")
+		httpserver.WriteAPIHelp(w, [][2]string{
+			{"/targets", "discovered targets list"},
+			{"/api/v1/targets", "advanced information about discovered targets in JSON format"},
+			{"/metrics", "available service metrics"},
+			{"/-/reload", "reload configuration"},
+		})
+		return true
+	}
+
+	path := strings.Replace(r.URL.Path, "//", "/", -1)
+	switch path {
+	case "/api/v1/write":
+		prometheusWriteRequests.Inc()
+		if err := promremotewrite.InsertHandler(nil, r); err != nil {
+			prometheusWriteErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "/api/v1/import":
+		vmimportRequests.Inc()
+		if err := vmimport.InsertHandler(nil, r); err != nil {
+			vmimportErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "/api/v1/import/csv":
+		csvimportRequests.Inc()
+		if err := csvimport.InsertHandler(nil, r); err != nil {
+			csvimportErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "/api/v1/import/prometheus":
+		prometheusimportRequests.Inc()
+		if err := prometheusimport.InsertHandler(nil, r); err != nil {
+			prometheusimportErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "/api/v1/import/native":
+		nativeimportRequests.Inc()
+		if err := native.InsertHandler(nil, r); err != nil {
+			nativeimportErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "/write", "/api/v2/write":
+		influxWriteRequests.Inc()
+		if err := influx.InsertHandlerForHTTP(nil, r); err != nil {
+			influxWriteErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "/query":
+		influxQueryRequests.Inc()
+		influxutils.WriteDatabaseNames(w)
+		return true
+	case "/datadog/api/v1/series":
+		datadogWriteRequests.Inc()
+		if err := datadog.InsertHandlerForHTTP(nil, r); err != nil {
+			datadogWriteErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		// See https://docs.datadoghq.com/api/latest/metrics/#submit-metrics
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.WriteHeader(202)
+		fmt.Fprintf(w, `{"status":"ok"}`)
+		return true
+	case "/datadog/api/v1/validate":
+		datadogValidateRequests.Inc()
+		// See https://docs.datadoghq.com/api/latest/authentication/#validate-api-key
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		fmt.Fprintf(w, `{"valid":true}`)
+		return true
+	case "/datadog/api/v1/check_run":
+		datadogCheckRunRequests.Inc()
+		// See https://docs.datadoghq.com/api/latest/service-checks/#submit-a-service-check
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.WriteHeader(202)
+		fmt.Fprintf(w, `{"status":"ok"}`)
+		return true
+	case "/datadog/intake/":
+		datadogIntakeRequests.Inc()
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		fmt.Fprintf(w, `{}`)
+		return true
+	case "/targets":
+		promscrapeTargetsRequests.Inc()
+		promscrape.WriteHumanReadableTargetsStatus(w, r)
+		return true
+	case "/api/v1/targets":
+		promscrapeAPIV1TargetsRequests.Inc()
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		state := r.FormValue("state")
+		promscrape.WriteAPIV1Targets(w, state)
+		return true
+	case "/-/reload":
+		promscrapeConfigReloadRequests.Inc()
+		procutil.SelfSIGHUP()
+		w.WriteHeader(http.StatusOK)
+		return true
+	case "/ready":
+		if rdy := atomic.LoadInt32(&promscrape.PendingScrapeConfigs); rdy > 0 {
+			errMsg := fmt.Sprintf("waiting for scrapes to init, left: %d", rdy)
+			http.Error(w, errMsg, http.StatusTooEarly)
+		} else {
+			w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+			w.WriteHeader(http.StatusOK)
+			w.Write([]byte("OK"))
+		}
+		return true
+	}
+	if remotewrite.MultitenancyEnabled() {
+		return processMultitenantRequest(w, r, path)
+	}
+	return false
+}
+
+func processMultitenantRequest(w http.ResponseWriter, r *http.Request, path string) bool {
+	p, err := httpserver.ParsePath(path)
+	if err != nil {
+		// Cannot parse multitenant path. Skip it - probably it will be parsed later.
+		return false
+	}
+	if p.Prefix != "insert" {
+		httpserver.Errorf(w, r, `unsupported multitenant prefix: %q; expected "insert"`, p.Prefix)
+		return true
+	}
+	at, err := auth.NewToken(p.AuthToken)
+	if err != nil {
+		httpserver.Errorf(w, r, "cannot obtain auth token: %s", err)
+		return true
+	}
+	switch p.Suffix {
+	case "prometheus/", "prometheus", "prometheus/api/v1/write":
+		prometheusWriteRequests.Inc()
+		if err := promremotewrite.InsertHandler(at, r); err != nil {
+			prometheusWriteErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "prometheus/api/v1/import":
+		vmimportRequests.Inc()
+		if err := vmimport.InsertHandler(at, r); err != nil {
+			vmimportErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "prometheus/api/v1/import/csv":
+		csvimportRequests.Inc()
+		if err := csvimport.InsertHandler(at, r); err != nil {
+			csvimportErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "prometheus/api/v1/import/prometheus":
+		prometheusimportRequests.Inc()
+		if err := prometheusimport.InsertHandler(at, r); err != nil {
+			prometheusimportErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "prometheus/api/v1/import/native":
+		nativeimportRequests.Inc()
+		if err := native.InsertHandler(at, r); err != nil {
+			nativeimportErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "influx/write", "influx/api/v2/write":
+		influxWriteRequests.Inc()
+		if err := influx.InsertHandlerForHTTP(at, r); err != nil {
+			influxWriteErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "influx/query":
+		influxQueryRequests.Inc()
+		influxutils.WriteDatabaseNames(w)
+		return true
+	case "datadog/api/v1/series":
+		datadogWriteRequests.Inc()
+		if err := datadog.InsertHandlerForHTTP(at, r); err != nil {
+			datadogWriteErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		// See https://docs.datadoghq.com/api/latest/metrics/#submit-metrics
+		w.WriteHeader(202)
+		fmt.Fprintf(w, `{"status":"ok"}`)
+		return true
+	case "datadog/api/v1/validate":
+		datadogValidateRequests.Inc()
+		// See https://docs.datadoghq.com/api/latest/authentication/#validate-api-key
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		fmt.Fprintf(w, `{"valid":true}`)
+		return true
+	case "datadog/api/v1/check_run":
+		datadogCheckRunRequests.Inc()
+		// See https://docs.datadoghq.com/api/latest/service-checks/#submit-a-service-check
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.WriteHeader(202)
+		fmt.Fprintf(w, `{"status":"ok"}`)
+		return true
+	case "datadog/intake/":
+		datadogIntakeRequests.Inc()
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		fmt.Fprintf(w, `{}`)
+		return true
+	default:
+		httpserver.Errorf(w, r, "unsupported multitenant path suffix: %q", p.Suffix)
+		return true
+	}
+}
+
+var (
+	prometheusWriteRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/api/v1/write", protocol="promremotewrite"}`)
+	prometheusWriteErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/api/v1/write", protocol="promremotewrite"}`)
+
+	vmimportRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/api/v1/import", protocol="vmimport"}`)
+	vmimportErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/api/v1/import", protocol="vmimport"}`)
+
+	csvimportRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/api/v1/import/csv", protocol="csvimport"}`)
+	csvimportErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/api/v1/import/csv", protocol="csvimport"}`)
+
+	prometheusimportRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/api/v1/import/prometheus", protocol="prometheusimport"}`)
+	prometheusimportErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/api/v1/import/prometheus", protocol="prometheusimport"}`)
+
+	nativeimportRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/api/v1/import/native", protocol="nativeimport"}`)
+	nativeimportErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/api/v1/import/native", protocol="nativeimport"}`)
+
+	influxWriteRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/influx/write", protocol="influx"}`)
+	influxWriteErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/influx/write", protocol="influx"}`)
+
+	influxQueryRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/influx/query", protocol="influx"}`)
+
+	datadogWriteRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/datadog/api/v1/series", protocol="datadog"}`)
+	datadogWriteErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/datadog/api/v1/series", protocol="datadog"}`)
+
+	datadogValidateRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/datadog/api/v1/validate", protocol="datadog"}`)
+	datadogCheckRunRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/datadog/api/v1/check_run", protocol="datadog"}`)
+	datadogIntakeRequests   = metrics.NewCounter(`vmagent_http_requests_total{path="/datadog/intake/", protocol="datadog"}`)
+
+	promscrapeTargetsRequests      = metrics.NewCounter(`vmagent_http_requests_total{path="/targets"}`)
+	promscrapeAPIV1TargetsRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/api/v1/targets"}`)
+
+	promscrapeConfigReloadRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/-/reload"}`)
+)
+
+func usage() {
+	const s = `
+vmagent collects metrics data via popular data ingestion protocols and routes it to VictoriaMetrics.
+
+See the docs at https://docs.victoriametrics.com/vmagent.html .
+`
+	flagutil.Usage(s)
+}

app/vmagent/multiarch/Dockerfile

@@ -0,0 +1,12 @@
+# See https://medium.com/on-docker/use-multi-stage-builds-to-inject-ca-certs-ad1e8f01de1b
+ARG certs_image
+ARG root_image
+FROM $certs_image as certs
+RUN apk --update --no-cache add ca-certificates
+
+FROM $root_image
+COPY --from=certs /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
+EXPOSE 8429
+ENTRYPOINT ["/vmagent-prod"]
+ARG TARGETARCH
+COPY vmagent-${TARGETARCH}-prod ./vmagent-prod

app/vmagent/native/request_handler.go

@@ -0,0 +1,91 @@
+package native
+
+import (
+	"net/http"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	parserCommon "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
+	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/native"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/tenantmetrics"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted       = metrics.NewCounter(`vmagent_rows_inserted_total{type="native"}`)
+	rowsTenantInserted = tenantmetrics.NewCounterMap(`vmagent_tenant_inserted_rows_total{type="native"}`)
+	rowsPerInsert      = metrics.NewHistogram(`vmagent_rows_per_insert{type="native"}`)
+)
+
+// InsertHandler processes `/api/v1/import` request.
+//
+// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6
+func InsertHandler(at *auth.Token, req *http.Request) error {
+	extraLabels, err := parserCommon.GetExtraLabels(req)
+	if err != nil {
+		return err
+	}
+	return writeconcurrencylimiter.Do(func() error {
+		return parser.ParseStream(req, func(block *parser.Block) error {
+			return insertRows(at, block, extraLabels)
+		})
+	})
+}
+
+func insertRows(at *auth.Token, block *parser.Block, extraLabels []prompbmarshal.Label) error {
+	ctx := common.GetPushCtx()
+	defer common.PutPushCtx(ctx)
+
+	// Update rowsInserted and rowsPerInsert before actual inserting,
+	// since relabeling can prevent from inserting the rows.
+	rowsLen := len(block.Values)
+	rowsInserted.Add(rowsLen)
+	if at != nil {
+		rowsTenantInserted.Get(at).Add(rowsLen)
+	}
+	rowsPerInsert.Update(float64(rowsLen))
+
+	tssDst := ctx.WriteRequest.Timeseries[:0]
+	labels := ctx.Labels[:0]
+	samples := ctx.Samples[:0]
+	mn := &block.MetricName
+	labelsLen := len(labels)
+	labels = append(labels, prompbmarshal.Label{
+		Name:  "__name__",
+		Value: bytesutil.ToUnsafeString(mn.MetricGroup),
+	})
+	for j := range mn.Tags {
+		tag := &mn.Tags[j]
+		labels = append(labels, prompbmarshal.Label{
+			Name:  bytesutil.ToUnsafeString(tag.Key),
+			Value: bytesutil.ToUnsafeString(tag.Value),
+		})
+	}
+	labels = append(labels, extraLabels...)
+	values := block.Values
+	timestamps := block.Timestamps
+	if len(timestamps) != len(values) {
+		logger.Panicf("BUG: len(timestamps)=%d must match len(values)=%d", len(timestamps), len(values))
+	}
+	samplesLen := len(samples)
+	for j, value := range values {
+		samples = append(samples, prompbmarshal.Sample{
+			Value:     value,
+			Timestamp: timestamps[j],
+		})
+	}
+	tssDst = append(tssDst, prompbmarshal.TimeSeries{
+		Labels:  labels[labelsLen:],
+		Samples: samples[samplesLen:],
+	})
+	ctx.WriteRequest.Timeseries = tssDst
+	ctx.Labels = labels
+	ctx.Samples = samples
+	remotewrite.PushWithAuthToken(at, &ctx.WriteRequest)
+	return nil
+}

app/vmagent/opentsdb/request_handler.go

@@ -0,0 +1,65 @@
+package opentsdb
+
+import (
+	"io"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/opentsdb"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted  = metrics.NewCounter(`vmagent_rows_inserted_total{type="opentsdb"}`)
+	rowsPerInsert = metrics.NewHistogram(`vmagent_rows_per_insert{type="opentsdb"}`)
+)
+
+// InsertHandler processes remote write for OpenTSDB put protocol.
+//
+// See http://opentsdb.net/docs/build/html/api_telnet/put.html
+func InsertHandler(r io.Reader) error {
+	return writeconcurrencylimiter.Do(func() error {
+		return parser.ParseStream(r, insertRows)
+	})
+}
+
+func insertRows(rows []parser.Row) error {
+	ctx := common.GetPushCtx()
+	defer common.PutPushCtx(ctx)
+
+	tssDst := ctx.WriteRequest.Timeseries[:0]
+	labels := ctx.Labels[:0]
+	samples := ctx.Samples[:0]
+	for i := range rows {
+		r := &rows[i]
+		labelsLen := len(labels)
+		labels = append(labels, prompbmarshal.Label{
+			Name:  "__name__",
+			Value: r.Metric,
+		})
+		for j := range r.Tags {
+			tag := &r.Tags[j]
+			labels = append(labels, prompbmarshal.Label{
+				Name:  tag.Key,
+				Value: tag.Value,
+			})
+		}
+		samples = append(samples, prompbmarshal.Sample{
+			Value:     r.Value,
+			Timestamp: r.Timestamp,
+		})
+		tssDst = append(tssDst, prompbmarshal.TimeSeries{
+			Labels:  labels[labelsLen:],
+			Samples: samples[len(samples)-1:],
+		})
+	}
+	ctx.WriteRequest.Timeseries = tssDst
+	ctx.Labels = labels
+	ctx.Samples = samples
+	remotewrite.Push(&ctx.WriteRequest)
+	rowsInserted.Add(len(rows))
+	rowsPerInsert.Update(float64(len(rows)))
+	return nil
+}

app/vmagent/opentsdbhttp/request_handler.go

@@ -0,0 +1,72 @@
+package opentsdbhttp
+
+import (
+	"net/http"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	parserCommon "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
+	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/opentsdbhttp"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted  = metrics.NewCounter(`vmagent_rows_inserted_total{type="opentsdbhttp"}`)
+	rowsPerInsert = metrics.NewHistogram(`vmagent_rows_per_insert{type="opentsdbhttp"}`)
+)
+
+// InsertHandler processes HTTP OpenTSDB put requests.
+// See http://opentsdb.net/docs/build/html/api_http/put.html
+func InsertHandler(req *http.Request) error {
+	extraLabels, err := parserCommon.GetExtraLabels(req)
+	if err != nil {
+		return err
+	}
+	return writeconcurrencylimiter.Do(func() error {
+		return parser.ParseStream(req, func(rows []parser.Row) error {
+			return insertRows(rows, extraLabels)
+		})
+	})
+}
+
+func insertRows(rows []parser.Row, extraLabels []prompbmarshal.Label) error {
+	ctx := common.GetPushCtx()
+	defer common.PutPushCtx(ctx)
+
+	tssDst := ctx.WriteRequest.Timeseries[:0]
+	labels := ctx.Labels[:0]
+	samples := ctx.Samples[:0]
+	for i := range rows {
+		r := &rows[i]
+		labelsLen := len(labels)
+		labels = append(labels, prompbmarshal.Label{
+			Name:  "__name__",
+			Value: r.Metric,
+		})
+		for j := range r.Tags {
+			tag := &r.Tags[j]
+			labels = append(labels, prompbmarshal.Label{
+				Name:  tag.Key,
+				Value: tag.Value,
+			})
+		}
+		labels = append(labels, extraLabels...)
+		samples = append(samples, prompbmarshal.Sample{
+			Value:     r.Value,
+			Timestamp: r.Timestamp,
+		})
+		tssDst = append(tssDst, prompbmarshal.TimeSeries{
+			Labels:  labels[labelsLen:],
+			Samples: samples[len(samples)-1:],
+		})
+	}
+	ctx.WriteRequest.Timeseries = tssDst
+	ctx.Labels = labels
+	ctx.Samples = samples
+	remotewrite.Push(&ctx.WriteRequest)
+	rowsInserted.Add(len(rows))
+	rowsPerInsert.Update(float64(len(rows)))
+	return nil
+}

app/vmagent/prometheusimport/request_handler.go

@@ -0,0 +1,92 @@
+package prometheusimport
+
+import (
+	"io"
+	"net/http"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	parserCommon "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
+	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/prometheus"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/tenantmetrics"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted       = metrics.NewCounter(`vmagent_rows_inserted_total{type="prometheus"}`)
+	rowsTenantInserted = tenantmetrics.NewCounterMap(`vmagent_tenant_inserted_rows_total{type="prometheus"}`)
+	rowsPerInsert      = metrics.NewHistogram(`vmagent_rows_per_insert{type="prometheus"}`)
+)
+
+// InsertHandler processes `/api/v1/import/prometheus` request.
+func InsertHandler(at *auth.Token, req *http.Request) error {
+	extraLabels, err := parserCommon.GetExtraLabels(req)
+	if err != nil {
+		return err
+	}
+	defaultTimestamp, err := parserCommon.GetTimestamp(req)
+	if err != nil {
+		return err
+	}
+	return writeconcurrencylimiter.Do(func() error {
+		isGzipped := req.Header.Get("Content-Encoding") == "gzip"
+		return parser.ParseStream(req.Body, defaultTimestamp, isGzipped, func(rows []parser.Row) error {
+			return insertRows(at, rows, extraLabels)
+		}, nil)
+	})
+}
+
+// InsertHandlerForReader processes metrics from given reader with optional gzip format
+func InsertHandlerForReader(r io.Reader, isGzipped bool) error {
+	return writeconcurrencylimiter.Do(func() error {
+		return parser.ParseStream(r, 0, isGzipped, func(rows []parser.Row) error {
+			return insertRows(nil, rows, nil)
+		}, nil)
+	})
+}
+
+func insertRows(at *auth.Token, rows []parser.Row, extraLabels []prompbmarshal.Label) error {
+	ctx := common.GetPushCtx()
+	defer common.PutPushCtx(ctx)
+
+	tssDst := ctx.WriteRequest.Timeseries[:0]
+	labels := ctx.Labels[:0]
+	samples := ctx.Samples[:0]
+	for i := range rows {
+		r := &rows[i]
+		labelsLen := len(labels)
+		labels = append(labels, prompbmarshal.Label{
+			Name:  "__name__",
+			Value: r.Metric,
+		})
+		for j := range r.Tags {
+			tag := &r.Tags[j]
+			labels = append(labels, prompbmarshal.Label{
+				Name:  tag.Key,
+				Value: tag.Value,
+			})
+		}
+		labels = append(labels, extraLabels...)
+		samples = append(samples, prompbmarshal.Sample{
+			Value:     r.Value,
+			Timestamp: r.Timestamp,
+		})
+		tssDst = append(tssDst, prompbmarshal.TimeSeries{
+			Labels:  labels[labelsLen:],
+			Samples: samples[len(samples)-1:],
+		})
+	}
+	ctx.WriteRequest.Timeseries = tssDst
+	ctx.Labels = labels
+	ctx.Samples = samples
+	remotewrite.PushWithAuthToken(at, &ctx.WriteRequest)
+	rowsInserted.Add(len(rows))
+	if at != nil {
+		rowsTenantInserted.Get(at).Add(len(rows))
+	}
+	rowsPerInsert.Update(float64(len(rows)))
+	return nil
+}

app/vmagent/promremotewrite/request_handler.go

@@ -0,0 +1,91 @@
+package promremotewrite
+
+import (
+	"io"
+	"net/http"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompb"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	parserCommon "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
+	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/promremotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/tenantmetrics"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted       = metrics.NewCounter(`vmagent_rows_inserted_total{type="promremotewrite"}`)
+	rowsTenantInserted = tenantmetrics.NewCounterMap(`vmagent_tenant_inserted_rows_total{type="promremotewrite"}`)
+	rowsPerInsert      = metrics.NewHistogram(`vmagent_rows_per_insert{type="promremotewrite"}`)
+)
+
+// InsertHandler processes remote write for prometheus.
+func InsertHandler(at *auth.Token, req *http.Request) error {
+	extraLabels, err := parserCommon.GetExtraLabels(req)
+	if err != nil {
+		return err
+	}
+	return writeconcurrencylimiter.Do(func() error {
+		return parser.ParseStream(req.Body, func(tss []prompb.TimeSeries) error {
+			return insertRows(at, tss, extraLabels)
+		})
+	})
+}
+
+// InsertHandlerForReader processes metrics from given reader
+func InsertHandlerForReader(at *auth.Token, r io.Reader) error {
+	return writeconcurrencylimiter.Do(func() error {
+		return parser.ParseStream(r, func(tss []prompb.TimeSeries) error {
+			return insertRows(at, tss, nil)
+		})
+	})
+}
+
+func insertRows(at *auth.Token, timeseries []prompb.TimeSeries, extraLabels []prompbmarshal.Label) error {
+	ctx := common.GetPushCtx()
+	defer common.PutPushCtx(ctx)
+
+	rowsTotal := 0
+	tssDst := ctx.WriteRequest.Timeseries[:0]
+	labels := ctx.Labels[:0]
+	samples := ctx.Samples[:0]
+	for i := range timeseries {
+		ts := &timeseries[i]
+		rowsTotal += len(ts.Samples)
+		labelsLen := len(labels)
+		for i := range ts.Labels {
+			label := &ts.Labels[i]
+			labels = append(labels, prompbmarshal.Label{
+				Name:  bytesutil.ToUnsafeString(label.Name),
+				Value: bytesutil.ToUnsafeString(label.Value),
+			})
+		}
+		labels = append(labels, extraLabels...)
+		samplesLen := len(samples)
+		for i := range ts.Samples {
+			sample := &ts.Samples[i]
+			samples = append(samples, prompbmarshal.Sample{
+				Value:     sample.Value,
+				Timestamp: sample.Timestamp,
+			})
+		}
+		tssDst = append(tssDst, prompbmarshal.TimeSeries{
+			Labels:  labels[labelsLen:],
+			Samples: samples[samplesLen:],
+		})
+	}
+	ctx.WriteRequest.Timeseries = tssDst
+	ctx.Labels = labels
+	ctx.Samples = samples
+	remotewrite.PushWithAuthToken(at, &ctx.WriteRequest)
+	rowsInserted.Add(rowsTotal)
+	if at != nil {
+		rowsTenantInserted.Get(at).Add(rowsTotal)
+	}
+	rowsPerInsert.Update(float64(rowsTotal))
+	return nil
+}

app/vmagent/remotewrite/client.go

@@ -0,0 +1,372 @@
+package remotewrite
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/persistentqueue"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promauth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/timerpool"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rateLimit = flagutil.NewArrayInt("remoteWrite.rateLimit", "Optional rate limit in bytes per second for data sent to -remoteWrite.url. "+
+		"By default the rate limit is disabled. It can be useful for limiting load on remote storage when big amounts of buffered data "+
+		"is sent after temporary unavailability of the remote storage")
+	sendTimeout = flagutil.NewArrayDuration("remoteWrite.sendTimeout", "Timeout for sending a single block of data to -remoteWrite.url")
+	proxyURL    = flagutil.NewArray("remoteWrite.proxyURL", "Optional proxy URL for writing data to -remoteWrite.url. Supported proxies: http, https, socks5. "+
+		"Example: -remoteWrite.proxyURL=socks5://proxy:1234")
+
+	tlsInsecureSkipVerify = flagutil.NewArrayBool("remoteWrite.tlsInsecureSkipVerify", "Whether to skip tls verification when connecting to -remoteWrite.url")
+	tlsCertFile           = flagutil.NewArray("remoteWrite.tlsCertFile", "Optional path to client-side TLS certificate file to use when connecting to -remoteWrite.url. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+	tlsKeyFile = flagutil.NewArray("remoteWrite.tlsKeyFile", "Optional path to client-side TLS certificate key to use when connecting to -remoteWrite.url. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+	tlsCAFile = flagutil.NewArray("remoteWrite.tlsCAFile", "Optional path to TLS CA file to use for verifying connections to -remoteWrite.url. "+
+		"By default system CA is used. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+	tlsServerName = flagutil.NewArray("remoteWrite.tlsServerName", "Optional TLS server name to use for connections to -remoteWrite.url. "+
+		"By default the server name from -remoteWrite.url is used. If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+
+	basicAuthUsername = flagutil.NewArray("remoteWrite.basicAuth.username", "Optional basic auth username to use for -remoteWrite.url. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+	basicAuthPassword = flagutil.NewArray("remoteWrite.basicAuth.password", "Optional basic auth password to use for -remoteWrite.url. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+	basicAuthPasswordFile = flagutil.NewArray("remoteWrite.basicAuth.passwordFile", "Optional path to basic auth password to use for -remoteWrite.url. "+
+		"The file is re-read every second. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+	bearerToken = flagutil.NewArray("remoteWrite.bearerToken", "Optional bearer auth token to use for -remoteWrite.url. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+	bearerTokenFile = flagutil.NewArray("remoteWrite.bearerTokenFile", "Optional path to bearer token file to use for -remoteWrite.url. "+
+		"The token is re-read from the file every second. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+
+	oauth2ClientID = flagutil.NewArray("remoteWrite.oauth2.clientID", "Optional OAuth2 clientID to use for -remoteWrite.url. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+	oauth2ClientSecret = flagutil.NewArray("remoteWrite.oauth2.clientSecret", "Optional OAuth2 clientSecret to use for -remoteWrite.url. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+	oauth2ClientSecretFile = flagutil.NewArray("remoteWrite.oauth2.clientSecretFile", "Optional OAuth2 clientSecretFile to use for -remoteWrite.url. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+	oauth2TokenURL = flagutil.NewArray("remoteWrite.oauth2.tokenUrl", "Optional OAuth2 tokenURL to use for -remoteWrite.url. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+	oauth2Scopes = flagutil.NewArray("remoteWrite.oauth2.scopes", "Optional OAuth2 scopes to use for -remoteWrite.url. Scopes must be delimited by ';'. "+
+		"If multiple args are set, then they are applied independently for the corresponding -remoteWrite.url")
+)
+
+type client struct {
+	sanitizedURL   string
+	remoteWriteURL string
+	fq             *persistentqueue.FastQueue
+	hc             *http.Client
+
+	sendBlock func(block []byte) bool
+	authCfg   *promauth.Config
+
+	rl rateLimiter
+
+	bytesSent       *metrics.Counter
+	blocksSent      *metrics.Counter
+	requestDuration *metrics.Histogram
+	requestsOKCount *metrics.Counter
+	errorsCount     *metrics.Counter
+	packetsDropped  *metrics.Counter
+	retriesCount    *metrics.Counter
+	sendDuration    *metrics.FloatCounter
+
+	wg     sync.WaitGroup
+	stopCh chan struct{}
+}
+
+func newHTTPClient(argIdx int, remoteWriteURL, sanitizedURL string, fq *persistentqueue.FastQueue, concurrency int) *client {
+	authCfg, err := getAuthConfig(argIdx)
+	if err != nil {
+		logger.Panicf("FATAL: cannot initialize auth config: %s", err)
+	}
+	tlsCfg := authCfg.NewTLSConfig()
+	tr := &http.Transport{
+		Dial:                statDial,
+		TLSClientConfig:     tlsCfg,
+		TLSHandshakeTimeout: 5 * time.Second,
+		MaxConnsPerHost:     2 * concurrency,
+		MaxIdleConnsPerHost: 2 * concurrency,
+		IdleConnTimeout:     time.Minute,
+		WriteBufferSize:     64 * 1024,
+	}
+	pURL := proxyURL.GetOptionalArg(argIdx)
+	if len(pURL) > 0 {
+		if !strings.Contains(pURL, "://") {
+			logger.Fatalf("cannot parse -remoteWrite.proxyURL=%q: it must start with `http://`, `https://` or `socks5://`", pURL)
+		}
+		urlProxy, err := url.Parse(pURL)
+		if err != nil {
+			logger.Fatalf("cannot parse -remoteWrite.proxyURL=%q: %s", pURL, err)
+		}
+		tr.Proxy = http.ProxyURL(urlProxy)
+	}
+	c := &client{
+		sanitizedURL:   sanitizedURL,
+		remoteWriteURL: remoteWriteURL,
+		authCfg:        authCfg,
+		fq:             fq,
+		hc: &http.Client{
+			Transport: tr,
+			Timeout:   sendTimeout.GetOptionalArgOrDefault(argIdx, time.Minute),
+		},
+		stopCh: make(chan struct{}),
+	}
+	c.sendBlock = c.sendBlockHTTP
+	return c
+}
+
+func (c *client) init(argIdx, concurrency int, sanitizedURL string) {
+	if bytesPerSec := rateLimit.GetOptionalArgOrDefault(argIdx, 0); bytesPerSec > 0 {
+		logger.Infof("applying %d bytes per second rate limit for -remoteWrite.url=%q", bytesPerSec, sanitizedURL)
+		c.rl.perSecondLimit = int64(bytesPerSec)
+	}
+	c.rl.limitReached = metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remote_write_rate_limit_reached_total{url=%q}`, c.sanitizedURL))
+
+	c.bytesSent = metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_bytes_sent_total{url=%q}`, c.sanitizedURL))
+	c.blocksSent = metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_blocks_sent_total{url=%q}`, c.sanitizedURL))
+	c.requestDuration = metrics.GetOrCreateHistogram(fmt.Sprintf(`vmagent_remotewrite_duration_seconds{url=%q}`, c.sanitizedURL))
+	c.requestsOKCount = metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_requests_total{url=%q, status_code="2XX"}`, c.sanitizedURL))
+	c.errorsCount = metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_errors_total{url=%q}`, c.sanitizedURL))
+	c.packetsDropped = metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_packets_dropped_total{url=%q}`, c.sanitizedURL))
+	c.retriesCount = metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_retries_count_total{url=%q}`, c.sanitizedURL))
+	c.sendDuration = metrics.GetOrCreateFloatCounter(fmt.Sprintf(`vmagent_remotewrite_send_duration_seconds_total{url=%q}`, c.sanitizedURL))
+	for i := 0; i < concurrency; i++ {
+		c.wg.Add(1)
+		go func() {
+			defer c.wg.Done()
+			c.runWorker()
+		}()
+	}
+	logger.Infof("initialized client for -remoteWrite.url=%q", c.sanitizedURL)
+}
+
+func (c *client) MustStop() {
+	close(c.stopCh)
+	c.wg.Wait()
+	logger.Infof("stopped client for -remoteWrite.url=%q", c.sanitizedURL)
+}
+
+func getAuthConfig(argIdx int) (*promauth.Config, error) {
+	username := basicAuthUsername.GetOptionalArg(argIdx)
+	password := basicAuthPassword.GetOptionalArg(argIdx)
+	passwordFile := basicAuthPasswordFile.GetOptionalArg(argIdx)
+	var basicAuthCfg *promauth.BasicAuthConfig
+	if username != "" || password != "" || passwordFile != "" {
+		basicAuthCfg = &promauth.BasicAuthConfig{
+			Username:     username,
+			Password:     password,
+			PasswordFile: passwordFile,
+		}
+	}
+
+	token := bearerToken.GetOptionalArg(argIdx)
+	tokenFile := bearerTokenFile.GetOptionalArg(argIdx)
+
+	var oauth2Cfg *promauth.OAuth2Config
+	clientSecret := oauth2ClientSecret.GetOptionalArg(argIdx)
+	clientSecretFile := oauth2ClientSecretFile.GetOptionalArg(argIdx)
+	if clientSecretFile != "" || clientSecret != "" {
+		oauth2Cfg = &promauth.OAuth2Config{
+			ClientID:         oauth2ClientID.GetOptionalArg(argIdx),
+			ClientSecret:     clientSecret,
+			ClientSecretFile: clientSecretFile,
+			TokenURL:         oauth2TokenURL.GetOptionalArg(argIdx),
+			Scopes:           strings.Split(oauth2Scopes.GetOptionalArg(argIdx), ";"),
+		}
+	}
+
+	tlsCfg := &promauth.TLSConfig{
+		CAFile:             tlsCAFile.GetOptionalArg(argIdx),
+		CertFile:           tlsCertFile.GetOptionalArg(argIdx),
+		KeyFile:            tlsKeyFile.GetOptionalArg(argIdx),
+		ServerName:         tlsServerName.GetOptionalArg(argIdx),
+		InsecureSkipVerify: tlsInsecureSkipVerify.GetOptionalArg(argIdx),
+	}
+
+	authCfg, err := promauth.NewConfig(".", nil, basicAuthCfg, token, tokenFile, oauth2Cfg, tlsCfg)
+	if err != nil {
+		return nil, fmt.Errorf("cannot populate OAuth2 config for remoteWrite idx: %d, err: %w", argIdx, err)
+	}
+	return authCfg, nil
+}
+
+func (c *client) runWorker() {
+	var ok bool
+	var block []byte
+	ch := make(chan bool, 1)
+	for {
+		block, ok = c.fq.MustReadBlock(block[:0])
+		if !ok {
+			return
+		}
+		go func() {
+			startTime := time.Now()
+			ch <- c.sendBlock(block)
+			c.sendDuration.Add(time.Since(startTime).Seconds())
+		}()
+		select {
+		case ok := <-ch:
+			if ok {
+				// The block has been sent successfully
+				continue
+			}
+			// Return unsent block to the queue.
+			c.fq.MustWriteBlock(block)
+			return
+		case <-c.stopCh:
+			// c must be stopped. Wait for a while in the hope the block will be sent.
+			graceDuration := 5 * time.Second
+			select {
+			case ok := <-ch:
+				if !ok {
+					// Return unsent block to the queue.
+					c.fq.MustWriteBlock(block)
+				}
+			case <-time.After(graceDuration):
+				// Return unsent block to the queue.
+				c.fq.MustWriteBlock(block)
+			}
+			return
+		}
+	}
+}
+
+// sendBlockHTTP returns false only if c.stopCh is closed.
+// Otherwise it tries sending the block to remote storage indefinitely.
+func (c *client) sendBlockHTTP(block []byte) bool {
+	c.rl.register(len(block), c.stopCh)
+	retryDuration := time.Second
+	retriesCount := 0
+	c.bytesSent.Add(len(block))
+	c.blocksSent.Inc()
+
+again:
+	req, err := http.NewRequest("POST", c.remoteWriteURL, bytes.NewBuffer(block))
+	if err != nil {
+		logger.Panicf("BUG: unexected error from http.NewRequest(%q): %s", c.sanitizedURL, err)
+	}
+	h := req.Header
+	h.Set("User-Agent", "vmagent")
+	h.Set("Content-Type", "application/x-protobuf")
+	h.Set("Content-Encoding", "snappy")
+	h.Set("X-Prometheus-Remote-Write-Version", "0.1.0")
+	if ah := c.authCfg.GetAuthHeader(); ah != "" {
+		req.Header.Set("Authorization", ah)
+	}
+
+	startTime := time.Now()
+	resp, err := c.hc.Do(req)
+	c.requestDuration.UpdateDuration(startTime)
+	if err != nil {
+		c.errorsCount.Inc()
+		retryDuration *= 2
+		if retryDuration > time.Minute {
+			retryDuration = time.Minute
+		}
+		logger.Warnf("couldn't send a block with size %d bytes to %q: %s; re-sending the block in %.3f seconds",
+			len(block), c.sanitizedURL, err, retryDuration.Seconds())
+		t := timerpool.Get(retryDuration)
+		select {
+		case <-c.stopCh:
+			timerpool.Put(t)
+			return false
+		case <-t.C:
+			timerpool.Put(t)
+		}
+		c.retriesCount.Inc()
+		goto again
+	}
+	statusCode := resp.StatusCode
+	if statusCode/100 == 2 {
+		_ = resp.Body.Close()
+		c.requestsOKCount.Inc()
+		return true
+	}
+	metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_requests_total{url=%q, status_code="%d"}`, c.sanitizedURL, statusCode)).Inc()
+	if statusCode == 409 || statusCode == 400 {
+		// Just drop block on 409 and 400 status codes like Prometheus does.
+		// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/873
+		// and https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1149
+		_ = resp.Body.Close()
+		c.packetsDropped.Inc()
+		return true
+	}
+
+	// Unexpected status code returned
+	retriesCount++
+	retryDuration *= 2
+	if retryDuration > time.Minute {
+		retryDuration = time.Minute
+	}
+	body, err := ioutil.ReadAll(resp.Body)
+	_ = resp.Body.Close()
+	if err != nil {
+		logger.Errorf("cannot read response body from %q during retry #%d: %s", c.sanitizedURL, retriesCount, err)
+	} else {
+		logger.Errorf("unexpected status code received after sending a block with size %d bytes to %q during retry #%d: %d; response body=%q; "+
+			"re-sending the block in %.3f seconds", len(block), c.sanitizedURL, retriesCount, statusCode, body, retryDuration.Seconds())
+	}
+	t := timerpool.Get(retryDuration)
+	select {
+	case <-c.stopCh:
+		timerpool.Put(t)
+		return false
+	case <-t.C:
+		timerpool.Put(t)
+	}
+	c.retriesCount.Inc()
+	goto again
+}
+
+type rateLimiter struct {
+	perSecondLimit int64
+
+	// mu protects budget and deadline from concurrent access.
+	mu sync.Mutex
+
+	// The current budget. It is increased by perSecondLimit every second.
+	budget int64
+
+	// The next deadline for increasing the budget by perSecondLimit
+	deadline time.Time
+
+	limitReached *metrics.Counter
+}
+
+func (rl *rateLimiter) register(dataLen int, stopCh <-chan struct{}) {
+	limit := rl.perSecondLimit
+	if limit <= 0 {
+		return
+	}
+
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+
+	for rl.budget <= 0 {
+		if d := time.Until(rl.deadline); d > 0 {
+			rl.limitReached.Inc()
+			t := timerpool.Get(d)
+			select {
+			case <-stopCh:
+				timerpool.Put(t)
+				return
+			case <-t.C:
+				timerpool.Put(t)
+			}
+		}
+		rl.budget += limit
+		rl.deadline = time.Now().Add(time.Second)
+	}
+	rl.budget -= int64(dataLen)
+}

app/vmagent/remotewrite/pendingseries.go

@@ -0,0 +1,232 @@
+package remotewrite
+
+import (
+	"flag"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/decimal"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/persistentqueue"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promrelabel"
+	"github.com/VictoriaMetrics/metrics"
+	"github.com/golang/snappy"
+)
+
+var (
+	flushInterval = flag.Duration("remoteWrite.flushInterval", time.Second, "Interval for flushing the data to remote storage. "+
+		"This option takes effect only when less than 10K data points per second are pushed to -remoteWrite.url")
+	maxUnpackedBlockSize = flagutil.NewBytes("remoteWrite.maxBlockSize", 8*1024*1024, "The maximum size in bytes of unpacked request to send to remote storage. "+
+		"It shouldn't exceed -maxInsertRequestSize from VictoriaMetrics")
+)
+
+// the maximum number of rows to send per each block.
+const maxRowsPerBlock = 10000
+
+// the maximum number of labels to send per each block.
+const maxLabelsPerBlock = 10 * maxRowsPerBlock
+
+type pendingSeries struct {
+	mu sync.Mutex
+	wr writeRequest
+
+	stopCh            chan struct{}
+	periodicFlusherWG sync.WaitGroup
+}
+
+func newPendingSeries(pushBlock func(block []byte), significantFigures, roundDigits int) *pendingSeries {
+	var ps pendingSeries
+	ps.wr.pushBlock = pushBlock
+	ps.wr.significantFigures = significantFigures
+	ps.wr.roundDigits = roundDigits
+	ps.stopCh = make(chan struct{})
+	ps.periodicFlusherWG.Add(1)
+	go func() {
+		defer ps.periodicFlusherWG.Done()
+		ps.periodicFlusher()
+	}()
+	return &ps
+}
+
+func (ps *pendingSeries) MustStop() {
+	close(ps.stopCh)
+	ps.periodicFlusherWG.Wait()
+}
+
+func (ps *pendingSeries) Push(tss []prompbmarshal.TimeSeries) {
+	ps.mu.Lock()
+	ps.wr.push(tss)
+	ps.mu.Unlock()
+}
+
+func (ps *pendingSeries) periodicFlusher() {
+	flushSeconds := int64(flushInterval.Seconds())
+	if flushSeconds <= 0 {
+		flushSeconds = 1
+	}
+	ticker := time.NewTicker(*flushInterval)
+	defer ticker.Stop()
+	mustStop := false
+	for !mustStop {
+		select {
+		case <-ps.stopCh:
+			mustStop = true
+		case <-ticker.C:
+			if fasttime.UnixTimestamp()-atomic.LoadUint64(&ps.wr.lastFlushTime) < uint64(flushSeconds) {
+				continue
+			}
+		}
+		ps.mu.Lock()
+		ps.wr.flush()
+		ps.mu.Unlock()
+	}
+}
+
+type writeRequest struct {
+	// Move lastFlushTime to the top of the struct in order to guarantee atomic access on 32-bit architectures.
+	lastFlushTime uint64
+
+	// pushBlock is called when whe write request is ready to be sent.
+	pushBlock func(block []byte)
+
+	// How many significant figures must be left before sending the writeRequest to pushBlock.
+	significantFigures int
+
+	// How many decimal digits after point must be left before sending the writeRequest to pushBlock.
+	roundDigits int
+
+	wr prompbmarshal.WriteRequest
+
+	tss []prompbmarshal.TimeSeries
+
+	labels  []prompbmarshal.Label
+	samples []prompbmarshal.Sample
+	buf     []byte
+}
+
+func (wr *writeRequest) reset() {
+	// Do not reset pushBlock, significantFigures and roundDigits, since they are re-used.
+
+	wr.wr.Timeseries = nil
+
+	for i := range wr.tss {
+		ts := &wr.tss[i]
+		ts.Labels = nil
+		ts.Samples = nil
+	}
+	wr.tss = wr.tss[:0]
+
+	promrelabel.CleanLabels(wr.labels)
+	wr.labels = wr.labels[:0]
+
+	wr.samples = wr.samples[:0]
+	wr.buf = wr.buf[:0]
+}
+
+func (wr *writeRequest) flush() {
+	wr.wr.Timeseries = wr.tss
+	wr.adjustSampleValues()
+	atomic.StoreUint64(&wr.lastFlushTime, fasttime.UnixTimestamp())
+	pushWriteRequest(&wr.wr, wr.pushBlock)
+	wr.reset()
+}
+
+func (wr *writeRequest) adjustSampleValues() {
+	samples := wr.samples
+	if n := wr.significantFigures; n > 0 {
+		for i := range samples {
+			s := &samples[i]
+			s.Value = decimal.RoundToSignificantFigures(s.Value, n)
+		}
+	}
+	if n := wr.roundDigits; n < 100 {
+		for i := range samples {
+			s := &samples[i]
+			s.Value = decimal.RoundToDecimalDigits(s.Value, n)
+		}
+	}
+}
+
+func (wr *writeRequest) push(src []prompbmarshal.TimeSeries) {
+	tssDst := wr.tss
+	for i := range src {
+		tssDst = append(tssDst, prompbmarshal.TimeSeries{})
+		wr.copyTimeSeries(&tssDst[len(tssDst)-1], &src[i])
+		if len(wr.samples) >= maxRowsPerBlock || len(wr.labels) >= maxLabelsPerBlock {
+			wr.tss = tssDst
+			wr.flush()
+			tssDst = wr.tss
+		}
+	}
+	wr.tss = tssDst
+}
+
+func (wr *writeRequest) copyTimeSeries(dst, src *prompbmarshal.TimeSeries) {
+	labelsDst := wr.labels
+	labelsLen := len(wr.labels)
+	samplesDst := wr.samples
+	buf := wr.buf
+	for i := range src.Labels {
+		labelsDst = append(labelsDst, prompbmarshal.Label{})
+		dstLabel := &labelsDst[len(labelsDst)-1]
+		srcLabel := &src.Labels[i]
+
+		buf = append(buf, srcLabel.Name...)
+		dstLabel.Name = bytesutil.ToUnsafeString(buf[len(buf)-len(srcLabel.Name):])
+		buf = append(buf, srcLabel.Value...)
+		dstLabel.Value = bytesutil.ToUnsafeString(buf[len(buf)-len(srcLabel.Value):])
+	}
+	dst.Labels = labelsDst[labelsLen:]
+
+	samplesDst = append(samplesDst, src.Samples...)
+	dst.Samples = samplesDst[len(samplesDst)-len(src.Samples):]
+
+	wr.samples = samplesDst
+	wr.labels = labelsDst
+	wr.buf = buf
+}
+
+func pushWriteRequest(wr *prompbmarshal.WriteRequest, pushBlock func(block []byte)) {
+	if len(wr.Timeseries) == 0 {
+		// Nothing to push
+		return
+	}
+	bb := writeRequestBufPool.Get()
+	bb.B = prompbmarshal.MarshalWriteRequest(bb.B[:0], wr)
+	if len(bb.B) <= maxUnpackedBlockSize.N {
+		zb := snappyBufPool.Get()
+		zb.B = snappy.Encode(zb.B[:cap(zb.B)], bb.B)
+		writeRequestBufPool.Put(bb)
+		if len(zb.B) <= persistentqueue.MaxBlockSize {
+			pushBlock(zb.B)
+			blockSizeRows.Update(float64(len(wr.Timeseries)))
+			blockSizeBytes.Update(float64(len(zb.B)))
+			snappyBufPool.Put(zb)
+			return
+		}
+		snappyBufPool.Put(zb)
+	} else {
+		writeRequestBufPool.Put(bb)
+	}
+
+	// Too big block. Recursively split it into smaller parts.
+	timeseries := wr.Timeseries
+	n := len(timeseries) / 2
+	wr.Timeseries = timeseries[:n]
+	pushWriteRequest(wr, pushBlock)
+	wr.Timeseries = timeseries[n:]
+	pushWriteRequest(wr, pushBlock)
+	wr.Timeseries = timeseries
+}
+
+var (
+	blockSizeBytes = metrics.NewHistogram(`vmagent_remotewrite_block_size_bytes`)
+	blockSizeRows  = metrics.NewHistogram(`vmagent_remotewrite_block_size_rows`)
+)
+
+var writeRequestBufPool bytesutil.ByteBufferPool
+var snappyBufPool bytesutil.ByteBufferPool

app/vmagent/remotewrite/relabel.go

@@ -0,0 +1,145 @@
+package remotewrite
+
+import (
+	"flag"
+	"fmt"
+	"strings"
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promrelabel"
+)
+
+var (
+	unparsedLabelsGlobal = flagutil.NewArray("remoteWrite.label", "Optional label in the form 'name=value' to add to all the metrics before sending them to -remoteWrite.url. "+
+		"Pass multiple -remoteWrite.label flags in order to add multiple labels to metrics before sending them to remote storage")
+	relabelConfigPathGlobal = flag.String("remoteWrite.relabelConfig", "", "Optional path to file with relabel_config entries. These entries are applied to all the metrics "+
+		"before sending them to -remoteWrite.url. See https://docs.victoriametrics.com/vmagent.html#relabeling for details")
+	relabelDebugGlobal = flag.Bool("remoteWrite.relabelDebug", false, "Whether to log metrics before and after relabeling with -remoteWrite.relabelConfig. "+
+		"If the -remoteWrite.relabelDebug is enabled, then the metrics aren't sent to remote storage. This is useful for debugging the relabeling configs")
+	relabelConfigPaths = flagutil.NewArray("remoteWrite.urlRelabelConfig", "Optional path to relabel config for the corresponding -remoteWrite.url")
+	relabelDebug       = flagutil.NewArrayBool("remoteWrite.urlRelabelDebug", "Whether to log metrics before and after relabeling with -remoteWrite.urlRelabelConfig. "+
+		"If the -remoteWrite.urlRelabelDebug is enabled, then the metrics aren't sent to the corresponding -remoteWrite.url. "+
+		"This is useful for debugging the relabeling configs")
+)
+
+var labelsGlobal []prompbmarshal.Label
+
+// CheckRelabelConfigs checks -remoteWrite.relabelConfig and -remoteWrite.urlRelabelConfig.
+func CheckRelabelConfigs() error {
+	_, err := loadRelabelConfigs()
+	return err
+}
+
+func loadRelabelConfigs() (*relabelConfigs, error) {
+	var rcs relabelConfigs
+	if *relabelConfigPathGlobal != "" {
+		global, err := promrelabel.LoadRelabelConfigs(*relabelConfigPathGlobal, *relabelDebugGlobal)
+		if err != nil {
+			return nil, fmt.Errorf("cannot load -remoteWrite.relabelConfig=%q: %w", *relabelConfigPathGlobal, err)
+		}
+		rcs.global = global
+	}
+	if len(*relabelConfigPaths) > (len(*remoteWriteURLs) + len(*remoteWriteMultitenantURLs)) {
+		return nil, fmt.Errorf("too many -remoteWrite.urlRelabelConfig args: %d; it mustn't exceed the number of -remoteWrite.url or -remoteWrite.multitenantURL args: %d",
+			len(*relabelConfigPaths), (len(*remoteWriteURLs) + len(*remoteWriteMultitenantURLs)))
+	}
+	rcs.perURL = make([]*promrelabel.ParsedConfigs, (len(*remoteWriteURLs) + len(*remoteWriteMultitenantURLs)))
+	for i, path := range *relabelConfigPaths {
+		if len(path) == 0 {
+			// Skip empty relabel config.
+			continue
+		}
+		prc, err := promrelabel.LoadRelabelConfigs(path, relabelDebug.GetOptionalArg(i))
+		if err != nil {
+			return nil, fmt.Errorf("cannot load relabel configs from -remoteWrite.urlRelabelConfig=%q: %w", path, err)
+		}
+		rcs.perURL[i] = prc
+	}
+	return &rcs, nil
+}
+
+type relabelConfigs struct {
+	global *promrelabel.ParsedConfigs
+	perURL []*promrelabel.ParsedConfigs
+}
+
+// initLabelsGlobal must be called after parsing command-line flags.
+func initLabelsGlobal() {
+	labelsGlobal = nil
+	for _, s := range *unparsedLabelsGlobal {
+		if len(s) == 0 {
+			continue
+		}
+		n := strings.IndexByte(s, '=')
+		if n < 0 {
+			logger.Fatalf("missing '=' in `-remoteWrite.label`. It must contain label in the form `name=value`; got %q", s)
+		}
+		labelsGlobal = append(labelsGlobal, prompbmarshal.Label{
+			Name:  s[:n],
+			Value: s[n+1:],
+		})
+	}
+}
+
+func (rctx *relabelCtx) applyRelabeling(tss []prompbmarshal.TimeSeries, extraLabels []prompbmarshal.Label, pcs *promrelabel.ParsedConfigs) []prompbmarshal.TimeSeries {
+	if len(extraLabels) == 0 && pcs.Len() == 0 {
+		// Nothing to change.
+		return tss
+	}
+	tssDst := tss[:0]
+	labels := rctx.labels[:0]
+	for i := range tss {
+		ts := &tss[i]
+		labelsLen := len(labels)
+		labels = append(labels, ts.Labels...)
+		// extraLabels must be added before applying relabeling according to https://prometheus.io/docs/prometheus/latest/configuration/configuration/#remote_write
+		for j := range extraLabels {
+			extraLabel := &extraLabels[j]
+			tmp := promrelabel.GetLabelByName(labels[labelsLen:], extraLabel.Name)
+			if tmp != nil {
+				tmp.Value = extraLabel.Value
+			} else {
+				labels = append(labels, *extraLabel)
+			}
+		}
+		labels = pcs.Apply(labels, labelsLen, true)
+		if len(labels) == labelsLen {
+			// Drop the current time series, since relabeling removed all the labels.
+			continue
+		}
+		tssDst = append(tssDst, prompbmarshal.TimeSeries{
+			Labels:  labels[labelsLen:],
+			Samples: ts.Samples,
+		})
+	}
+	rctx.labels = labels
+	return tssDst
+}
+
+type relabelCtx struct {
+	// pool for labels, which are used during the relabeling.
+	labels []prompbmarshal.Label
+}
+
+func (rctx *relabelCtx) reset() {
+	promrelabel.CleanLabels(rctx.labels)
+	rctx.labels = rctx.labels[:0]
+}
+
+var relabelCtxPool = &sync.Pool{
+	New: func() interface{} {
+		return &relabelCtx{}
+	},
+}
+
+func getRelabelCtx() *relabelCtx {
+	return relabelCtxPool.Get().(*relabelCtx)
+}
+
+func putRelabelCtx(rctx *relabelCtx) {
+	rctx.labels = rctx.labels[:0]
+	relabelCtxPool.Put(rctx)
+}

app/vmagent/remotewrite/remotewrite.go

@@ -0,0 +1,503 @@
+package remotewrite
+
+import (
+	"flag"
+	"fmt"
+	"net/url"
+	"strconv"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bloomfilter"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/memory"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/persistentqueue"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promrelabel"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/tenantmetrics"
+	"github.com/VictoriaMetrics/metrics"
+	xxhash "github.com/cespare/xxhash/v2"
+)
+
+var (
+	remoteWriteURLs = flagutil.NewArray("remoteWrite.url", "Remote storage URL to write data to. It must support Prometheus remote_write API. "+
+		"It is recommended using VictoriaMetrics as remote storage. Example url: http://<victoriametrics-host>:8428/api/v1/write . "+
+		"Pass multiple -remoteWrite.url flags in order to replicate data to multiple remote storage systems. See also -remoteWrite.multitenantURL")
+	remoteWriteMultitenantURLs = flagutil.NewArray("remoteWrite.multitenantURL", "Base path for multitenant remote storage URL to write data to. "+
+		"See https://docs.victoriametrics.com/vmagent.html#multitenancy for details. Example url: http://<vminsert>:8480 . "+
+		"Pass multiple -remoteWrite.multitenantURL flags in order to replicate data to multiple remote storage systems. See also -remoteWrite.url")
+	tmpDataPath = flag.String("remoteWrite.tmpDataPath", "vmagent-remotewrite-data", "Path to directory where temporary data for remote write component is stored. "+
+		"See also -remoteWrite.maxDiskUsagePerURL")
+	queues = flag.Int("remoteWrite.queues", cgroup.AvailableCPUs()*2, "The number of concurrent queues to each -remoteWrite.url. Set more queues if default number of queues "+
+		"isn't enough for sending high volume of collected data to remote storage. Default value is 2 * numberOfAvailableCPUs")
+	showRemoteWriteURL = flag.Bool("remoteWrite.showURL", false, "Whether to show -remoteWrite.url in the exported metrics. "+
+		"It is hidden by default, since it can contain sensitive info such as auth key")
+	maxPendingBytesPerURL = flagutil.NewBytes("remoteWrite.maxDiskUsagePerURL", 0, "The maximum file-based buffer size in bytes at -remoteWrite.tmpDataPath "+
+		"for each -remoteWrite.url. When buffer size reaches the configured maximum, then old data is dropped when adding new data to the buffer. "+
+		"Buffered data is stored in ~500MB chunks, so the minimum practical value for this flag is 500000000. "+
+		"Disk usage is unlimited if the value is set to 0")
+	significantFigures = flagutil.NewArrayInt("remoteWrite.significantFigures", "The number of significant figures to leave in metric values before writing them "+
+		"to remote storage. See https://en.wikipedia.org/wiki/Significant_figures . Zero value saves all the significant figures. "+
+		"This option may be used for improving data compression for the stored metrics. See also -remoteWrite.roundDigits")
+	roundDigits = flagutil.NewArrayInt("remoteWrite.roundDigits", "Round metric values to this number of decimal digits after the point before writing them to remote storage. "+
+		"Examples: -remoteWrite.roundDigits=2 would round 1.236 to 1.24, while -remoteWrite.roundDigits=-1 would round 126.78 to 130. "+
+		"By default digits rounding is disabled. Set it to 100 for disabling it for a particular remote storage. "+
+		"This option may be used for improving data compression for the stored metrics")
+	sortLabels = flag.Bool("sortLabels", false, `Whether to sort labels for incoming samples before writing them to all the configured remote storage systems. `+
+		`This may be needed for reducing memory usage at remote storage when the order of labels in incoming samples is random. `+
+		`For example, if m{k1="v1",k2="v2"} may be sent as m{k2="v2",k1="v1"}`+
+		`Enabled sorting for labels can slow down ingestion performance a bit`)
+	maxHourlySeries = flag.Int("remoteWrite.maxHourlySeries", 0, "The maximum number of unique series vmagent can send to remote storage systems during the last hour. "+
+		"Excess series are logged and dropped. This can be useful for limiting series cardinality. See https://docs.victoriametrics.com/vmagent.html#cardinality-limiter")
+	maxDailySeries = flag.Int("remoteWrite.maxDailySeries", 0, "The maximum number of unique series vmagent can send to remote storage systems during the last 24 hours. "+
+		"Excess series are logged and dropped. This can be useful for limiting series churn rate. See https://docs.victoriametrics.com/vmagent.html#cardinality-limiter")
+)
+
+var (
+	// rwctxsDefault contains statically populated entries when -remoteWrite.url is specified.
+	rwctxsDefault []*remoteWriteCtx
+
+	// rwctxsMap contains dynamically populated entries when -remoteWrite.multitenantURL is specified.
+	rwctxsMap     = make(map[tenantmetrics.TenantID][]*remoteWriteCtx)
+	rwctxsMapLock sync.Mutex
+
+	// Data without tenant id is written to defaultAuthToken if -remoteWrite.multitenantURL is specified.
+	defaultAuthToken = &auth.Token{}
+)
+
+// MultitenancyEnabled returns true if -remoteWrite.multitenantURL is specified.
+func MultitenancyEnabled() bool {
+	return len(*remoteWriteMultitenantURLs) > 0
+}
+
+// Contains the current relabelConfigs.
+var allRelabelConfigs atomic.Value
+
+// maxQueues limits the maximum value for `-remoteWrite.queues`. There is no sense in setting too high value,
+// since it may lead to high memory usage due to big number of buffers.
+var maxQueues = cgroup.AvailableCPUs() * 16
+
+// InitSecretFlags must be called after flag.Parse and before any logging.
+func InitSecretFlags() {
+	if !*showRemoteWriteURL {
+		// remoteWrite.url can contain authentication codes, so hide it at `/metrics` output.
+		flagutil.RegisterSecretFlag("remoteWrite.url")
+	}
+}
+
+// Init initializes remotewrite.
+//
+// It must be called after flag.Parse().
+//
+// Stop must be called for graceful shutdown.
+func Init() {
+	if len(*remoteWriteURLs) == 0 && len(*remoteWriteMultitenantURLs) == 0 {
+		logger.Fatalf("at least one `-remoteWrite.url` or `-remoteWrite.multitenantURL` command-line flag must be set")
+	}
+	if len(*remoteWriteURLs) > 0 && len(*remoteWriteMultitenantURLs) > 0 {
+		logger.Fatalf("cannot set both `-remoteWrite.url` and `-remoteWrite.multitenantURL` command-line flags")
+	}
+	if *maxHourlySeries > 0 {
+		hourlySeriesLimiter = bloomfilter.NewLimiter(*maxHourlySeries, time.Hour)
+		_ = metrics.NewGauge(`vmagent_hourly_series_limit_max_series`, func() float64 {
+			return float64(hourlySeriesLimiter.MaxItems())
+		})
+		_ = metrics.NewGauge(`vmagent_hourly_series_limit_current_series`, func() float64 {
+			return float64(hourlySeriesLimiter.CurrentItems())
+		})
+	}
+	if *maxDailySeries > 0 {
+		dailySeriesLimiter = bloomfilter.NewLimiter(*maxDailySeries, 24*time.Hour)
+		_ = metrics.NewGauge(`vmagent_daily_series_limit_max_series`, func() float64 {
+			return float64(dailySeriesLimiter.MaxItems())
+		})
+		_ = metrics.NewGauge(`vmagent_daily_series_limit_current_series`, func() float64 {
+			return float64(dailySeriesLimiter.CurrentItems())
+		})
+	}
+	if *queues > maxQueues {
+		*queues = maxQueues
+	}
+	if *queues <= 0 {
+		*queues = 1
+	}
+	initLabelsGlobal()
+
+	// Register SIGHUP handler for config reload before loadRelabelConfigs.
+	// This guarantees that the config will be re-read if the signal arrives just after loadRelabelConfig.
+	// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1240
+	sighupCh := procutil.NewSighupChan()
+
+	rcs, err := loadRelabelConfigs()
+	if err != nil {
+		logger.Fatalf("cannot load relabel configs: %s", err)
+	}
+	allRelabelConfigs.Store(rcs)
+
+	if len(*remoteWriteURLs) > 0 {
+		rwctxsDefault = newRemoteWriteCtxs(nil, *remoteWriteURLs)
+	}
+
+	// Start config reloader.
+	configReloaderWG.Add(1)
+	go func() {
+		defer configReloaderWG.Done()
+		for {
+			select {
+			case <-sighupCh:
+			case <-stopCh:
+				return
+			}
+			logger.Infof("SIGHUP received; reloading relabel configs pointed by -remoteWrite.relabelConfig and -remoteWrite.urlRelabelConfig")
+			rcs, err := loadRelabelConfigs()
+			if err != nil {
+				logger.Errorf("cannot reload relabel configs; preserving the previous configs; error: %s", err)
+				continue
+			}
+			allRelabelConfigs.Store(rcs)
+			logger.Infof("Successfully reloaded relabel configs")
+		}
+	}()
+}
+
+func newRemoteWriteCtxs(at *auth.Token, urls []string) []*remoteWriteCtx {
+	if len(urls) == 0 {
+		logger.Panicf("BUG: urls must be non-empty")
+	}
+
+	maxInmemoryBlocks := memory.Allowed() / len(urls) / maxRowsPerBlock / 100
+	if maxInmemoryBlocks > 400 {
+		// There is no much sense in keeping higher number of blocks in memory,
+		// since this means that the producer outperforms consumer and the queue
+		// will continue growing. It is better storing the queue to file.
+		maxInmemoryBlocks = 400
+	}
+	if maxInmemoryBlocks < 2 {
+		maxInmemoryBlocks = 2
+	}
+	rwctxs := make([]*remoteWriteCtx, len(urls))
+	for i, remoteWriteURLRaw := range urls {
+		remoteWriteURL, err := url.Parse(remoteWriteURLRaw)
+		if err != nil {
+			logger.Fatalf("invalid -remoteWrite.url=%q: %s", remoteWriteURL, err)
+		}
+		sanitizedURL := fmt.Sprintf("%d:secret-url", i+1)
+		if at != nil {
+			// Construct full remote_write url for the given tenant according to https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#url-format
+			remoteWriteURL.Path = fmt.Sprintf("%s/insert/%d:%d/prometheus/api/v1/write", remoteWriteURL.Path, at.AccountID, at.ProjectID)
+			sanitizedURL = fmt.Sprintf("%s:%d:%d", sanitizedURL, at.AccountID, at.ProjectID)
+		}
+		if *showRemoteWriteURL {
+			sanitizedURL = fmt.Sprintf("%d:%s", i+1, remoteWriteURL)
+		}
+		rwctxs[i] = newRemoteWriteCtx(i, at, remoteWriteURL, maxInmemoryBlocks, sanitizedURL)
+	}
+	return rwctxs
+}
+
+var stopCh = make(chan struct{})
+var configReloaderWG sync.WaitGroup
+
+// Stop stops remotewrite.
+//
+// It is expected that nobody calls Push during and after the call to this func.
+func Stop() {
+	close(stopCh)
+	configReloaderWG.Wait()
+
+	for _, rwctx := range rwctxsDefault {
+		rwctx.MustStop()
+	}
+	rwctxsDefault = nil
+
+	// There is no need in locking rwctxsMapLock here, since nobody should call Push during the Stop call.
+	for _, rwctxs := range rwctxsMap {
+		for _, rwctx := range rwctxs {
+			rwctx.MustStop()
+		}
+	}
+	rwctxsMap = nil
+
+	if sl := hourlySeriesLimiter; sl != nil {
+		sl.MustStop()
+	}
+	if sl := dailySeriesLimiter; sl != nil {
+		sl.MustStop()
+	}
+}
+
+// Push sends wr to remote storage systems set via `-remoteWrite.url`.
+//
+// Note that wr may be modified by Push due to relabeling and rounding.
+func Push(wr *prompbmarshal.WriteRequest) {
+	PushWithAuthToken(nil, wr)
+}
+
+// PushWithAuthToken sends wr to remote storage systems set via `-remoteWrite.multitenantURL`.
+//
+// Note that wr may be modified by Push due to relabeling and rounding.
+func PushWithAuthToken(at *auth.Token, wr *prompbmarshal.WriteRequest) {
+	if at == nil && len(*remoteWriteMultitenantURLs) > 0 {
+		// Write data to default tenant if at isn't set while -remoteWrite.multitenantURL is set.
+		at = defaultAuthToken
+	}
+	var rwctxs []*remoteWriteCtx
+	if at == nil {
+		rwctxs = rwctxsDefault
+	} else {
+		if len(*remoteWriteMultitenantURLs) == 0 {
+			logger.Panicf("BUG: remoteWriteMultitenantURLs must be non-empty for non-nil at")
+		}
+		rwctxsMapLock.Lock()
+		tenantID := tenantmetrics.TenantID{
+			AccountID: at.AccountID,
+			ProjectID: at.ProjectID,
+		}
+		rwctxs = rwctxsMap[tenantID]
+		if rwctxs == nil {
+			rwctxs = newRemoteWriteCtxs(at, *remoteWriteMultitenantURLs)
+			rwctxsMap[tenantID] = rwctxs
+		}
+		rwctxsMapLock.Unlock()
+	}
+
+	var rctx *relabelCtx
+	rcs := allRelabelConfigs.Load().(*relabelConfigs)
+	pcsGlobal := rcs.global
+	if pcsGlobal.Len() > 0 || len(labelsGlobal) > 0 {
+		rctx = getRelabelCtx()
+	}
+	tss := wr.Timeseries
+	for len(tss) > 0 {
+		// Process big tss in smaller blocks in order to reduce the maximum memory usage
+		samplesCount := 0
+		labelsCount := 0
+		i := 0
+		for i < len(tss) {
+			samplesCount += len(tss[i].Samples)
+			labelsCount += len(tss[i].Labels)
+			i++
+			if samplesCount >= maxRowsPerBlock || labelsCount >= maxLabelsPerBlock {
+				break
+			}
+		}
+		tssBlock := tss
+		if i < len(tss) {
+			tssBlock = tss[:i]
+			tss = tss[i:]
+		} else {
+			tss = nil
+		}
+		if rctx != nil {
+			tssBlockLen := len(tssBlock)
+			tssBlock = rctx.applyRelabeling(tssBlock, labelsGlobal, pcsGlobal)
+			globalRelabelMetricsDropped.Add(tssBlockLen - len(tssBlock))
+		}
+		sortLabelsIfNeeded(tssBlock)
+		tssBlock = limitSeriesCardinality(tssBlock)
+		if len(tssBlock) > 0 {
+			for _, rwctx := range rwctxs {
+				rwctx.Push(tssBlock)
+			}
+		}
+		if rctx != nil {
+			rctx.reset()
+		}
+	}
+	if rctx != nil {
+		putRelabelCtx(rctx)
+	}
+}
+
+// sortLabelsIfNeeded sorts labels if -sortLabels command-line flag is set.
+func sortLabelsIfNeeded(tss []prompbmarshal.TimeSeries) {
+	if !*sortLabels {
+		return
+	}
+	for i := range tss {
+		promrelabel.SortLabels(tss[i].Labels)
+	}
+}
+
+func limitSeriesCardinality(tss []prompbmarshal.TimeSeries) []prompbmarshal.TimeSeries {
+	if hourlySeriesLimiter == nil && dailySeriesLimiter == nil {
+		return tss
+	}
+	dst := make([]prompbmarshal.TimeSeries, 0, len(tss))
+	for i := range tss {
+		labels := tss[i].Labels
+		h := getLabelsHash(labels)
+		if hourlySeriesLimiter != nil && !hourlySeriesLimiter.Add(h) {
+			hourlySeriesLimitRowsDropped.Add(len(tss[i].Samples))
+			logSkippedSeries(labels, "-remoteWrite.maxHourlySeries", hourlySeriesLimiter.MaxItems())
+			continue
+		}
+		if dailySeriesLimiter != nil && !dailySeriesLimiter.Add(h) {
+			dailySeriesLimitRowsDropped.Add(len(tss[i].Samples))
+			logSkippedSeries(labels, "-remoteWrite.maxDailySeries", dailySeriesLimiter.MaxItems())
+			continue
+		}
+		dst = append(dst, tss[i])
+	}
+	return dst
+}
+
+var (
+	hourlySeriesLimiter *bloomfilter.Limiter
+	dailySeriesLimiter  *bloomfilter.Limiter
+
+	hourlySeriesLimitRowsDropped = metrics.NewCounter(`vmagent_hourly_series_limit_rows_dropped_total`)
+	dailySeriesLimitRowsDropped  = metrics.NewCounter(`vmagent_daily_series_limit_rows_dropped_total`)
+)
+
+func getLabelsHash(labels []prompbmarshal.Label) uint64 {
+	bb := labelsHashBufPool.Get()
+	b := bb.B[:0]
+	for _, label := range labels {
+		b = append(b, label.Name...)
+		b = append(b, label.Value...)
+	}
+	h := xxhash.Sum64(b)
+	bb.B = b
+	labelsHashBufPool.Put(bb)
+	return h
+}
+
+var labelsHashBufPool bytesutil.ByteBufferPool
+
+func logSkippedSeries(labels []prompbmarshal.Label, flagName string, flagValue int) {
+	select {
+	case <-logSkippedSeriesTicker.C:
+		logger.Warnf("skip series %s because %s=%d reached", labelsToString(labels), flagName, flagValue)
+	default:
+	}
+}
+
+var logSkippedSeriesTicker = time.NewTicker(5 * time.Second)
+
+func labelsToString(labels []prompbmarshal.Label) string {
+	var b []byte
+	b = append(b, '{')
+	for i, label := range labels {
+		b = append(b, label.Name...)
+		b = append(b, '=')
+		b = strconv.AppendQuote(b, label.Value)
+		if i+1 < len(labels) {
+			b = append(b, ',')
+		}
+	}
+	b = append(b, '}')
+	return string(b)
+}
+
+var globalRelabelMetricsDropped = metrics.NewCounter("vmagent_remotewrite_global_relabel_metrics_dropped_total")
+
+type remoteWriteCtx struct {
+	idx        int
+	fq         *persistentqueue.FastQueue
+	c          *client
+	pss        []*pendingSeries
+	pssNextIdx uint64
+
+	relabelMetricsDropped *metrics.Counter
+}
+
+func newRemoteWriteCtx(argIdx int, at *auth.Token, remoteWriteURL *url.URL, maxInmemoryBlocks int, sanitizedURL string) *remoteWriteCtx {
+	// strip query params, otherwise changing params resets pq
+	pqURL := *remoteWriteURL
+	pqURL.RawQuery = ""
+	pqURL.Fragment = ""
+	h := xxhash.Sum64([]byte(pqURL.String()))
+	queuePath := fmt.Sprintf("%s/persistent-queue/%d_%016X", *tmpDataPath, argIdx+1, h)
+	fq := persistentqueue.MustOpenFastQueue(queuePath, sanitizedURL, maxInmemoryBlocks, maxPendingBytesPerURL.N)
+	_ = metrics.GetOrCreateGauge(fmt.Sprintf(`vmagent_remotewrite_pending_data_bytes{path=%q, url=%q}`, queuePath, sanitizedURL), func() float64 {
+		return float64(fq.GetPendingBytes())
+	})
+	_ = metrics.GetOrCreateGauge(fmt.Sprintf(`vmagent_remotewrite_pending_inmemory_blocks{path=%q, url=%q}`, queuePath, sanitizedURL), func() float64 {
+		return float64(fq.GetInmemoryQueueLen())
+	})
+	var c *client
+	switch remoteWriteURL.Scheme {
+	case "http", "https":
+		c = newHTTPClient(argIdx, remoteWriteURL.String(), sanitizedURL, fq, *queues)
+	default:
+		logger.Fatalf("unsupported scheme: %s for remoteWriteURL: %s, want `http`, `https`", remoteWriteURL.Scheme, sanitizedURL)
+	}
+	c.init(argIdx, *queues, sanitizedURL)
+
+	sf := significantFigures.GetOptionalArgOrDefault(argIdx, 0)
+	rd := roundDigits.GetOptionalArgOrDefault(argIdx, 100)
+	pssLen := *queues
+	if n := cgroup.AvailableCPUs(); pssLen > n {
+		// There is no sense in running more than availableCPUs concurrent pendingSeries,
+		// since every pendingSeries can saturate up to a single CPU.
+		pssLen = n
+	}
+	pss := make([]*pendingSeries, pssLen)
+	for i := range pss {
+		pss[i] = newPendingSeries(fq.MustWriteBlock, sf, rd)
+	}
+	return &remoteWriteCtx{
+		idx: argIdx,
+		fq:  fq,
+		c:   c,
+		pss: pss,
+
+		relabelMetricsDropped: metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_relabel_metrics_dropped_total{path=%q, url=%q}`, queuePath, sanitizedURL)),
+	}
+}
+
+func (rwctx *remoteWriteCtx) MustStop() {
+	for _, ps := range rwctx.pss {
+		ps.MustStop()
+	}
+	rwctx.idx = 0
+	rwctx.pss = nil
+	rwctx.fq.UnblockAllReaders()
+	rwctx.c.MustStop()
+	rwctx.c = nil
+	rwctx.fq.MustClose()
+	rwctx.fq = nil
+
+	rwctx.relabelMetricsDropped = nil
+}
+
+func (rwctx *remoteWriteCtx) Push(tss []prompbmarshal.TimeSeries) {
+	var rctx *relabelCtx
+	var v *[]prompbmarshal.TimeSeries
+	rcs := allRelabelConfigs.Load().(*relabelConfigs)
+	pcs := rcs.perURL[rwctx.idx]
+	if pcs.Len() > 0 {
+		rctx = getRelabelCtx()
+		// Make a copy of tss before applying relabeling in order to prevent
+		// from affecting time series for other remoteWrite.url configs.
+		// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/467
+		// and https://github.com/VictoriaMetrics/VictoriaMetrics/issues/599
+		v = tssRelabelPool.Get().(*[]prompbmarshal.TimeSeries)
+		tss = append(*v, tss...)
+		tssLen := len(tss)
+		tss = rctx.applyRelabeling(tss, nil, pcs)
+		rwctx.relabelMetricsDropped.Add(tssLen - len(tss))
+	}
+	pss := rwctx.pss
+	idx := atomic.AddUint64(&rwctx.pssNextIdx, 1) % uint64(len(pss))
+	pss[idx].Push(tss)
+	if rctx != nil {
+		*v = prompbmarshal.ResetTimeSeries(tss)
+		tssRelabelPool.Put(v)
+		putRelabelCtx(rctx)
+	}
+}
+
+var tssRelabelPool = &sync.Pool{
+	New: func() interface{} {
+		a := []prompbmarshal.TimeSeries{}
+		return &a
+	},
+}

app/vmagent/remotewrite/statconn.go

@@ -0,0 +1,73 @@
+package remotewrite
+
+import (
+	"net"
+	"sync/atomic"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/netutil"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+func statDial(networkUnused, addr string) (conn net.Conn, err error) {
+	network := netutil.GetTCPNetwork()
+	conn, err = net.DialTimeout(network, addr, 5*time.Second)
+	dialsTotal.Inc()
+	if err != nil {
+		dialErrors.Inc()
+		return nil, err
+	}
+	conns.Inc()
+	sc := &statConn{
+		Conn: conn,
+	}
+	return sc, nil
+}
+
+var (
+	dialsTotal = metrics.NewCounter(`vmagent_remotewrite_dials_total`)
+	dialErrors = metrics.NewCounter(`vmagent_remotewrite_dial_errors_total`)
+	conns      = metrics.NewCounter(`vmagent_remotewrite_conns`)
+)
+
+type statConn struct {
+	closed uint64
+	net.Conn
+}
+
+func (sc *statConn) Read(p []byte) (int, error) {
+	n, err := sc.Conn.Read(p)
+	connReadsTotal.Inc()
+	if err != nil {
+		connReadErrors.Inc()
+	}
+	connBytesRead.Add(n)
+	return n, err
+}
+
+func (sc *statConn) Write(p []byte) (int, error) {
+	n, err := sc.Conn.Write(p)
+	connWritesTotal.Inc()
+	if err != nil {
+		connWriteErrors.Inc()
+	}
+	connBytesWritten.Add(n)
+	return n, err
+}
+
+func (sc *statConn) Close() error {
+	err := sc.Conn.Close()
+	if atomic.AddUint64(&sc.closed, 1) == 1 {
+		conns.Dec()
+	}
+	return err
+}
+
+var (
+	connReadsTotal   = metrics.NewCounter(`vmagent_remotewrite_conn_reads_total`)
+	connWritesTotal  = metrics.NewCounter(`vmagent_remotewrite_conn_writes_total`)
+	connReadErrors   = metrics.NewCounter(`vmagent_remotewrite_conn_read_errors_total`)
+	connWriteErrors  = metrics.NewCounter(`vmagent_remotewrite_conn_write_errors_total`)
+	connBytesRead    = metrics.NewCounter(`vmagent_remotewrite_conn_bytes_read_total`)
+	connBytesWritten = metrics.NewCounter(`vmagent_remotewrite_conn_bytes_written_total`)
+)

app/vmagent/vmimport/request_handler.go

@@ -0,0 +1,98 @@
+package vmimport
+
+import (
+	"io"
+	"net/http"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	parserCommon "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
+	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/vmimport"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/tenantmetrics"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted       = metrics.NewCounter(`vmagent_rows_inserted_total{type="vmimport"}`)
+	rowsTenantInserted = tenantmetrics.NewCounterMap(`vmagent_tenant_inserted_rows_total{type="vmimport"}`)
+	rowsPerInsert      = metrics.NewHistogram(`vmagent_rows_per_insert{type="vmimport"}`)
+)
+
+// InsertHandler processes `/api/v1/import` request.
+//
+// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6
+func InsertHandler(at *auth.Token, req *http.Request) error {
+	extraLabels, err := parserCommon.GetExtraLabels(req)
+	if err != nil {
+		return err
+	}
+	return writeconcurrencylimiter.Do(func() error {
+		isGzipped := req.Header.Get("Content-Encoding") == "gzip"
+		return parser.ParseStream(req.Body, isGzipped, func(rows []parser.Row) error {
+			return insertRows(at, rows, extraLabels)
+		})
+	})
+}
+
+// InsertHandlerForReader processes metrics from given reader
+func InsertHandlerForReader(r io.Reader, isGzipped bool) error {
+	return writeconcurrencylimiter.Do(func() error {
+		return parser.ParseStream(r, isGzipped, func(rows []parser.Row) error {
+			return insertRows(nil, rows, nil)
+		})
+	})
+}
+
+func insertRows(at *auth.Token, rows []parser.Row, extraLabels []prompbmarshal.Label) error {
+	ctx := common.GetPushCtx()
+	defer common.PutPushCtx(ctx)
+
+	rowsTotal := 0
+	tssDst := ctx.WriteRequest.Timeseries[:0]
+	labels := ctx.Labels[:0]
+	samples := ctx.Samples[:0]
+	for i := range rows {
+		r := &rows[i]
+		rowsTotal += len(r.Values)
+		labelsLen := len(labels)
+		for j := range r.Tags {
+			tag := &r.Tags[j]
+			labels = append(labels, prompbmarshal.Label{
+				Name:  bytesutil.ToUnsafeString(tag.Key),
+				Value: bytesutil.ToUnsafeString(tag.Value),
+			})
+		}
+		labels = append(labels, extraLabels...)
+		values := r.Values
+		timestamps := r.Timestamps
+		if len(timestamps) != len(values) {
+			logger.Panicf("BUG: len(timestamps)=%d must match len(values)=%d", len(timestamps), len(values))
+		}
+		samplesLen := len(samples)
+		for j, value := range values {
+			samples = append(samples, prompbmarshal.Sample{
+				Value:     value,
+				Timestamp: timestamps[j],
+			})
+		}
+		tssDst = append(tssDst, prompbmarshal.TimeSeries{
+			Labels:  labels[labelsLen:],
+			Samples: samples[samplesLen:],
+		})
+	}
+	ctx.WriteRequest.Timeseries = tssDst
+	ctx.Labels = labels
+	ctx.Samples = samples
+	remotewrite.PushWithAuthToken(at, &ctx.WriteRequest)
+	rowsInserted.Add(rowsTotal)
+	if at != nil {
+		rowsTenantInserted.Get(at).Add(rowsTotal)
+	}
+	rowsPerInsert.Update(float64(rowsTotal))
+	return nil
+}

app/vmalert/Makefile

@@ -0,0 +1,107 @@
+# All these commands must run from repository root.
+
+vmalert:
+	APP_NAME=vmalert $(MAKE) app-local
+
+vmalert-race:
+	APP_NAME=vmalert RACE=-race $(MAKE) app-local
+
+vmalert-prod:
+	APP_NAME=vmalert $(MAKE) app-via-docker
+
+vmalert-pure-prod:
+	APP_NAME=vmalert $(MAKE) app-via-docker-pure
+
+vmalert-amd64-prod:
+	APP_NAME=vmalert $(MAKE) app-via-docker-amd64
+
+vmalert-arm-prod:
+	APP_NAME=vmalert $(MAKE) app-via-docker-arm
+
+vmalert-arm64-prod:
+	APP_NAME=vmalert $(MAKE) app-via-docker-arm64
+
+vmalert-ppc64le-prod:
+	APP_NAME=vmalert $(MAKE) app-via-docker-ppc64le
+
+vmalert-386-prod:
+	APP_NAME=vmalert $(MAKE) app-via-docker-386
+
+package-vmalert:
+	APP_NAME=vmalert $(MAKE) package-via-docker
+
+package-vmalert-pure:
+	APP_NAME=vmalert $(MAKE) package-via-docker-pure
+
+package-vmalert-amd64:
+	APP_NAME=vmalert $(MAKE) package-via-docker-amd64
+
+package-vmalert-arm:
+	APP_NAME=vmalert $(MAKE) package-via-docker-arm
+
+package-vmalert-arm64:
+	APP_NAME=vmalert $(MAKE) package-via-docker-arm64
+
+package-vmalert-ppc64le:
+	APP_NAME=vmalert $(MAKE) package-via-docker-ppc64le
+
+package-vmalert-386:
+	APP_NAME=vmalert $(MAKE) package-via-docker-386
+
+publish-vmalert:
+	APP_NAME=vmalert $(MAKE) publish-via-docker
+
+test-vmalert:
+	go test -v -race -cover ./app/vmalert -loggerLevel=ERROR
+	go test -v -race -cover ./app/vmalert/datasource
+	go test -v -race -cover ./app/vmalert/notifier
+	go test -v -race -cover ./app/vmalert/config
+	go test -v -race -cover ./app/vmalert/remotewrite
+
+run-vmalert: vmalert
+	./bin/vmalert -rule=app/vmalert/config/testdata/rules2-good.rules \
+		-datasource.url=http://localhost:8428 \
+		-notifier.url=http://localhost:9093 \
+		-notifier.url=http://127.0.0.1:9093 \
+		-remoteWrite.url=http://localhost:8428 \
+		-remoteRead.url=http://localhost:8428 \
+		-external.label=cluster=east-1 \
+		-external.label=replica=a \
+		-evaluationInterval=3s \
+		-rule.configCheckInterval=10s
+
+replay-vmalert: vmalert
+	./bin/vmalert -rule=app/vmalert/config/testdata/rules-replay-good.rules \
+		-datasource.url=http://localhost:8428 \
+		-remoteWrite.url=http://localhost:8428 \
+		-external.label=cluster=east-1 \
+		-external.label=replica=a \
+		-replay.timeFrom=2021-05-11T07:21:43Z \
+		-replay.timeTo=2021-05-29T18:40:43Z
+
+vmalert-amd64:
+	CGO_ENABLED=1 GOARCH=amd64 $(MAKE) vmalert-local-with-goarch
+
+vmalert-arm:
+	CGO_ENABLED=0 GOARCH=arm $(MAKE) vmalert-local-with-goarch
+
+vmalert-arm64:
+	CGO_ENABLED=0 GOARCH=arm64 $(MAKE) vmalert-local-with-goarch
+
+vmalert-ppc64le:
+	CGO_ENABLED=0 GOARCH=ppc64le $(MAKE) vmalert-local-with-goarch
+
+vmalert-386:
+	CGO_ENABLED=0 GOARCH=386 $(MAKE) vmalert-local-with-goarch
+
+vmalert-local-with-goarch:
+	APP_NAME=vmalert $(MAKE) app-local-with-goarch
+
+vmalert-pure:
+	APP_NAME=vmalert $(MAKE) app-local-pure
+
+vmalert-windows-amd64:
+	GOARCH=amd64 APP_NAME=vmalert $(MAKE) app-local-windows-with-goarch
+
+vmalert-windows-amd64-prod:
+	APP_NAME=vmalert $(MAKE) app-via-docker-windows-amd64

app/vmalert/README.md

@@ -0,0 +1,630 @@
+# vmalert
+
+`vmalert` executes a list of the given [alerting](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/)
+or [recording](https://prometheus.io/docs/prometheus/latest/configuration/recording_rules/)
+rules against configured address. It is heavily inspired by [Prometheus](https://prometheus.io/docs/alerting/latest/overview/)
+implementation and aims to be compatible with its syntax.
+
+## Features
+* Integration with [VictoriaMetrics](https://github.com/VictoriaMetrics/VictoriaMetrics) TSDB;
+* VictoriaMetrics [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html)
+ support and expressions validation;
+* Prometheus [alerting rules definition format](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/#defining-alerting-rules)
+ support;
+* Integration with [Alertmanager](https://github.com/prometheus/alertmanager);
+* Keeps the alerts [state on restarts](#alerts-state-on-restarts);
+* Graphite datasource can be used for alerting and recording rules. See [these docs](#graphite);
+* Recording and Alerting rules backfilling (aka `replay`). See [these docs](#rules-backfilling);
+* Lightweight without extra dependencies.
+
+## Limitations
+* `vmalert` execute queries against remote datasource which has reliability risks because of network.
+It is recommended to configure alerts thresholds and rules expressions with understanding that network request
+may fail;
+* by default, rules execution is sequential within one group, but persisting of execution results to remote
+storage is asynchronous. Hence, user shouldn't rely on recording rules chaining when result of previous
+recording rule is reused in next one;
+
+## QuickStart
+
+To build `vmalert` from sources:
+```
+git clone https://github.com/VictoriaMetrics/VictoriaMetrics
+cd VictoriaMetrics
+make vmalert
+```
+The build binary will be placed to `VictoriaMetrics/bin` folder.
+
+To start using `vmalert` you will need the following things:
+* list of rules - PromQL/MetricsQL expressions to execute;
+* datasource address - reachable VictoriaMetrics instance for rules execution;
+* notifier address - reachable [Alert Manager](https://github.com/prometheus/alertmanager) instance for processing,
+aggregating alerts and sending notifications.
+* remote write address [optional] - [remote write](https://prometheus.io/docs/prometheus/latest/storage/#remote-storage-integrations)
+compatible storage address for storing recording rules results and alerts state in for of timeseries.
+
+Then configure `vmalert` accordingly:
+```
+./bin/vmalert -rule=alert.rules \            # Path to the file with rules configuration. Supports wildcard
+    -datasource.url=http://localhost:8428 \  # PromQL compatible datasource
+    -notifier.url=http://localhost:9093 \    # AlertManager URL
+    -notifier.url=http://127.0.0.1:9093 \    # AlertManager replica URL
+    -remoteWrite.url=http://localhost:8428 \ # Remote write compatible storage to persist rules
+    -remoteRead.url=http://localhost:8428 \  # MetricsQL compatible datasource to restore alerts state from
+    -external.label=cluster=east-1 \         # External label to be applied for each rule
+    -external.label=replica=a                # Multiple external labels may be set
+```
+
+See the fill list of configuration flags in [configuration](#configuration) section.
+
+If you run multiple `vmalert` services for the same datastore or AlertManager - do not forget
+to specify different `external.label` flags in order to define which `vmalert` generated rules or alerts.
+
+Configuration for [recording](https://prometheus.io/docs/prometheus/latest/configuration/recording_rules/)
+and [alerting](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/) rules is very
+similar to Prometheus rules and configured using YAML. Configuration examples may be found
+in [testdata](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmalert/config/testdata) folder.
+Every `rule` belongs to a `group` and every configuration file may contain arbitrary number of groups:
+```yaml
+groups:
+  [ - <rule_group> ]
+```
+
+### Groups
+
+Each group has the following attributes:
+```yaml
+# The name of the group. Must be unique within a file.
+name: <string>
+
+# How often rules in the group are evaluated.
+[ interval: <duration> | default = -evaluationInterval flag ]
+
+# How many rules execute at once within a group. Increasing concurrency may speed
+# up round execution speed.
+[ concurrency: <integer> | default = 1 ]
+
+# Optional type for expressions inside the rules. Supported values: "graphite" and "prometheus".
+# By default "prometheus" rule type is used.
+[ type: <string> ]
+
+# Optional list of label filters applied to every rule's
+# request withing a group. Is compatible only with VM datasource.
+# See more details at https://docs.victoriametrics.com#prometheus-querying-api-enhancements
+extra_filter_labels:
+  [ <labelname>: <labelvalue> ... ]
+
+# Optional list of labels added to every rule within a group.
+# It has priority over the external labels.
+# Labels are commonly used for adding environment
+# or tenant-specific tag.
+labels:
+  [ <labelname>: <labelvalue> ... ]
+
+rules:
+  [ - <rule> ... ]
+```
+
+### Rules
+
+Every rule contains `expr` field for [PromQL](https://prometheus.io/docs/prometheus/latest/querying/basics/)
+or [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html) expression. Vmalert will execute the configured
+expression and then act according to the Rule type.
+
+There are two types of Rules:
+* [alerting](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/) -
+Alerting rules allows to define alert conditions via `expr` field and to send notifications
+[Alertmanager](https://github.com/prometheus/alertmanager) if execution result is not empty.
+* [recording](https://prometheus.io/docs/prometheus/latest/configuration/recording_rules/) -
+Recording rules allows to define `expr` which result will be than backfilled to configured
+`-remoteWrite.url`. Recording rules are used to precompute frequently needed or computationally
+expensive expressions and save their result as a new set of time series.
+
+`vmalert` forbids to define duplicates - rules with the same combination of name, expression and labels
+within one group.
+
+#### Alerting rules
+
+The syntax for alerting rule is the following:
+```yaml
+# The name of the alert. Must be a valid metric name.
+alert: <string>
+
+# Optional type for the rule. Supported values: "graphite", "prometheus".
+# By default "prometheus" rule type is used.
+[ type: <string> ]
+
+# The expression to evaluate. The expression language depends on the type value.
+# By default PromQL/MetricsQL expression is used. If type="graphite", then the expression
+# must contain valid Graphite expression.
+expr: <string>
+
+# Alerts are considered firing once they have been returned for this long.
+# Alerts which have not yet fired for long enough are considered pending.
+# If param is omitted or set to 0 then alerts will be immediately considered
+# as firing once they return.
+[ for: <duration> | default = 0s ]
+
+# Labels to add or overwrite for each alert.
+labels:
+  [ <labelname>: <tmpl_string> ]
+
+# Annotations to add to each alert.
+annotations:
+  [ <labelname>: <tmpl_string> ]
+```
+
+It is allowed to use [Go templating](https://golang.org/pkg/text/template/) in annotations
+to format data, iterate over it or execute expressions.
+Additionally, `vmalert` provides some extra templating functions
+listed [here](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmalert/notifier/template_func.go).
+
+#### Recording rules
+
+The syntax for recording rules is following:
+```yaml
+# The name of the time series to output to. Must be a valid metric name.
+record: <string>
+
+# Optional type for the rule. Supported values: "graphite", "prometheus".
+# By default "prometheus" rule type is used.
+[ type: <string> ]
+
+# The expression to evaluate. The expression language depends on the type value.
+# By default MetricsQL expression is used. If type="graphite", then the expression
+# must contain valid Graphite expression.
+expr: <string>
+
+# Labels to add or overwrite before storing the result.
+labels:
+  [ <labelname>: <labelvalue> ]
+```
+
+For recording rules to work `-remoteWrite.url` must be specified.
+
+
+### Alerts state on restarts
+
+`vmalert` has no local storage, so alerts state is stored in the process memory. Hence, after restart of `vmalert`
+the process alerts state will be lost. To avoid this situation, `vmalert` should be configured via the following flags:
+* `-remoteWrite.url` - URL to VictoriaMetrics (Single) or vminsert (Cluster). `vmalert` will persist alerts state
+into the configured address in the form of time series named `ALERTS` and `ALERTS_FOR_STATE` via remote-write protocol.
+These are regular time series and may be queried from VM just as any other time series.
+The state stored to the configured address on every rule evaluation.
+* `-remoteRead.url` - URL to VictoriaMetrics (Single) or vmselect (Cluster). `vmalert` will try to restore alerts state
+from configured address by querying time series with name `ALERTS_FOR_STATE`.
+
+Both flags are required for the proper state restoring. Restore process may fail if time series are missing
+in configured `-remoteRead.url`, weren't updated in the last `1h` (controlled by `-remoteRead.lookback`)
+or received state doesn't match current `vmalert` rules configuration.
+
+
+### Multitenancy
+
+There are the following approaches for alerting and recording rules across
+[multiple tenants](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#multitenancy):
+
+* To run a separate `vmalert` instance per each tenant.
+  The corresponding tenant must be specified in `-datasource.url` command-line flag
+  according to [these docs](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#url-format).
+  For example, `/path/to/vmalert -datasource.url=http://vmselect:8481/select/123/prometheus`
+  would run alerts against `AccountID=123`. For recording rules the `-remoteWrite.url` command-line
+  flag must contain the url for the specific tenant as well.
+  For example, `-remoteWrite.url=http://vminsert:8480/insert/123/prometheus` would write recording
+  rules to `AccountID=123`.
+
+* To specify `tenant` parameter per each alerting and recording group if
+  [enterprise version of vmalert](https://victoriametrics.com/enterprise.html) is used
+  with `-clusterMode` command-line flag. For example:
+
+```yaml
+groups:
+- name: rules_for_tenant_123
+  tenant: "123"
+  rules:
+    # Rules for accountID=123
+
+- name: rules_for_tenant_456:789
+  tenant: "456:789"
+  rules:
+    # Rules for accountID=456, projectID=789
+```
+
+If `-clusterMode` is enabled, then `-datasource.url`, `-remoteRead.url` and `-remoteWrite.url` must
+contain only the hostname without tenant id. For example: `-datasource.url=http://vmselect:8481`.
+`vmalert` automatically adds the specified tenant to urls per each recording rule in this case.
+
+The enterprise version of vmalert is available in `vmutils-*-enterprise.tar.gz` files
+at [release page](https://github.com/VictoriaMetrics/VictoriaMetrics/releases) and in `*-enterprise`
+tags at [Docker Hub](https://hub.docker.com/r/victoriametrics/vmalert/tags).
+
+
+### WEB
+
+`vmalert` runs a web-server (`-httpListenAddr`) for serving metrics and alerts endpoints:
+* `http://<vmalert-addr>` - UI;
+* `http://<vmalert-addr>/api/v1/groups` - list of all loaded groups and rules;
+* `http://<vmalert-addr>/api/v1/alerts` - list of all active alerts;
+* `http://<vmalert-addr>/api/v1/<groupID>/<alertID>/status" ` - get alert status by ID.
+Used as alert source in AlertManager.
+* `http://<vmalert-addr>/metrics` - application metrics.
+* `http://<vmalert-addr>/-/reload` - hot configuration reload.
+
+
+## Graphite
+
+vmalert sends requests to `<-datasource.url>/render?format=json` during evaluation of alerting and recording rules
+if the corresponding group or rule contains `type: "graphite"` config option. It is expected that the `<-datasource.url>/render`
+implements [Graphite Render API](https://graphite.readthedocs.io/en/stable/render_api.html) for `format=json`.
+When using vmalert with both `graphite` and `prometheus` rules configured against cluster version of VM do not forget
+to set `-datasource.appendTypePrefix` flag to `true`, so vmalert can adjust URL prefix automatically based on query type.
+
+## Rules backfilling
+
+vmalert supports alerting and recording rules backfilling (aka `replay`). In replay mode vmalert
+can read the same rules configuration as normally, evaluate them on the given time range and backfill
+results via remote write to the configured storage. vmalert supports any PromQL/MetricsQL compatible
+data source for backfilling.
+
+### How it works
+
+In `replay` mode vmalert works as a cli-tool and exits immediately after work is done.
+To run vmalert in `replay` mode:
+```
+./bin/vmalert -rule=path/to/your.rules \        # path to files with rules you usually use with vmalert
+    -datasource.url=http://localhost:8428 \     # PromQL/MetricsQL compatible datasource
+    -remoteWrite.url=http://localhost:8428 \    # remote write compatible storage to persist results
+    -replay.timeFrom=2021-05-11T07:21:43Z \     # time from begin replay
+    -replay.timeTo=2021-05-29T18:40:43Z         # time to finish replay
+```
+
+The output of the command will look like the following:
+```
+Replay mode:
+from:   2021-05-11 07:21:43 +0000 UTC   # set by -replay.timeFrom
+to:     2021-05-29 18:40:43 +0000 UTC   # set by -replay.timeTo
+max data points per request: 1000       # set by -replay.maxDatapointsPerQuery
+
+Group "ReplayGroup"
+interval:       1m0s
+requests to make:       27
+max range per request:  16h40m0s
+> Rule "type:vm_cache_entries:rate5m" (ID: 1792509946081842725)
+27 / 27 [----------------------------------------------------------------------------------------------------] 100.00% 78 p/s
+> Rule "go_cgo_calls_count:rate5m" (ID: 17958425467471411582)
+27 / 27 [-----------------------------------------------------------------------------------------------------] 100.00% ? p/s
+
+Group "vmsingleReplay"
+interval:       30s
+requests to make:       54
+max range per request:  8h20m0s
+> Rule "RequestErrorsToAPI" (ID: 17645863024999990222)
+54 / 54 [-----------------------------------------------------------------------------------------------------] 100.00% ? p/s
+> Rule "TooManyLogs" (ID: 9042195394653477652)
+54 / 54 [-----------------------------------------------------------------------------------------------------] 100.00% ? p/s
+2021-06-07T09:59:12.098Z        info    app/vmalert/replay.go:68        replay finished! Imported 511734 samples
+```
+
+In `replay` mode all groups are executed sequentially one-by-one. Rules within the group are
+executed sequentially as well (`concurrency` setting is ignored). Vmalert sends rule's expression
+to [/query_range](https://prometheus.io/docs/prometheus/latest/querying/api/#range-queries) endpoint
+of the configured `-datasource.url`. Returned data then processed according to the rule type and
+backfilled to `-remoteWrite.url` via [Remote Write protocol](https://prometheus.io/docs/prometheus/latest/storage/#remote-storage-integrations).
+Vmalert respects `evaluationInterval` value set by flag or per-group during the replay.
+Vmalert automatically disables caching on VictoriaMetrics side by sending `nocache=1` param. It allows
+to prevent cache pollution and unwanted time range boundaries adjustment during backfilling.
+
+#### Recording rules
+
+Result of recording rules `replay` should match with results of normal rules evaluation.
+
+#### Alerting rules
+
+Result of alerting rules `replay` is time series reflecting [alert's state](#alerts-state-on-restarts).
+To see if `replayed` alert has fired in the past use the following PromQL/MetricsQL expression:
+```
+ALERTS{alertname="your_alertname", alertstate="firing"}
+```
+Execute the query against storage which was used for `-remoteWrite.url` during the `replay`.
+
+### Additional configuration
+
+There are following non-required `replay` flags:
+
+* `-replay.maxDatapointsPerQuery` - the max number of data points expected to receive in one request.
+In two words, it affects the max time range for every `/query_range` request. The higher the value,
+the less requests will be issued during `replay`.
+* `-replay.ruleRetryAttempts` - when datasource fails to respond vmalert will make this number of retries
+per rule before giving up.
+* `-replay.rulesDelay` - delay between sequential rules execution. Important in cases if there are chaining
+(rules which depend on each other) rules. It is expected, that remote storage will be able to persist
+previously accepted data during the delay, so data will be available for the subsequent queries.
+Keep it equal or bigger than `-remoteWrite.flushInterval`.
+
+See full description for these flags in `./vmalert --help`.
+
+### Limitations
+
+* Graphite engine isn't supported yet;
+* `query` template function is disabled for performance reasons (might be changed in future);
+
+
+## Monitoring
+
+`vmalert` exports various metrics in Prometheus exposition format at `http://vmalert-host:8880/metrics` page. 
+We recommend setting up regular scraping of this page either through `vmagent` or by Prometheus so that the exported 
+metrics may be analyzed later.
+
+Use official [Grafana dashboard](https://grafana.com/grafana/dashboards/14950) for `vmalert` overview.
+If you have suggestions for improvements or have found a bug - please open an issue on github or add 
+a review to the dashboard.
+
+
+## Configuration
+
+Pass `-help` to `vmalert` in order to see the full list of supported
+command-line flags with their descriptions.
+
+The shortlist of configuration flags is the following:
+```
+  -datasource.appendTypePrefix
+    	Whether to add type prefix to -datasource.url based on the query type. Set to true if sending different query types to the vmselect URL.
+  -datasource.basicAuth.password string
+    	Optional basic auth password for -datasource.url
+  -datasource.basicAuth.passwordFile string
+    	Optional path to basic auth password to use for -datasource.url
+  -datasource.basicAuth.username string
+    	Optional basic auth username for -datasource.url
+  -datasource.bearerToken string
+    	Optional bearer auth token to use for -datasource.url.
+  -datasource.bearerTokenFile string
+    	Optional path to bearer token file to use for -datasource.url.
+  -datasource.lookback duration
+    	Lookback defines how far into the past to look when evaluating queries. For example, if the datasource.lookback=5m then param "time" with value now()-5m will be added to every query.
+  -datasource.maxIdleConnections int
+    	Defines the number of idle (keep-alive connections) to each configured datasource. Consider setting this value equal to the value: groups_total * group.concurrency. Too low a value may result in a high number of sockets in TIME_WAIT state. (default 100)
+  -datasource.queryStep duration
+    	queryStep defines how far a value can fallback to when evaluating queries. For example, if datasource.queryStep=15s then param "step" with value "15s" will be added to every query.If queryStep isn't specified, rule's evaluationInterval will be used instead.
+  -datasource.roundDigits int
+    	Adds "round_digits" GET param to datasource requests. In VM "round_digits" limits the number of digits after the decimal point in response values.
+  -datasource.tlsCAFile string
+    	Optional path to TLS CA file to use for verifying connections to -datasource.url. By default, system CA is used
+  -datasource.tlsCertFile string
+    	Optional path to client-side TLS certificate file to use when connecting to -datasource.url
+  -datasource.tlsInsecureSkipVerify
+    	Whether to skip tls verification when connecting to -datasource.url
+  -datasource.tlsKeyFile string
+    	Optional path to client-side TLS certificate key to use when connecting to -datasource.url
+  -datasource.tlsServerName string
+    	Optional TLS server name to use for connections to -datasource.url. By default, the server name from -datasource.url is used
+  -datasource.url string
+    	VictoriaMetrics or vmselect url. Required parameter. E.g. http://127.0.0.1:8428
+  -disableAlertgroupLabel
+    	Whether to disable adding group's name as label to generated alerts and time series.
+  -dryRun -rule
+    	Whether to check only config files without running vmalert. The rules file are validated. The -rule flag must be specified.
+  -enableTCP6
+    	Whether to enable IPv6 for listening and dialing. By default only IPv4 TCP and UDP is used
+  -envflag.enable
+    	Whether to enable reading flags from environment variables additionally to command line. Command line flag values have priority over values from environment vars. Flags are read only from command line if this flag isn't set. See https://docs.victoriametrics.com/#environment-variables for more details
+  -envflag.prefix string
+    	Prefix for environment variables if -envflag.enable is set
+  -evaluationInterval duration
+    	How often to evaluate the rules (default 1m0s)
+  -external.alert.source string
+    	External Alert Source allows to override the Source link for alerts sent to AlertManager for cases where you want to build a custom link to Grafana, Prometheus or any other service.
+    	eg. 'explore?orgId=1&left=[\"now-1h\",\"now\",\"VictoriaMetrics\",{\"expr\": \"{{$expr|quotesEscape|crlfEscape|queryEscape}}\"},{\"mode\":\"Metrics\"},{\"ui\":[true,true,true,\"none\"]}]'.If empty '/api/v1/:groupID/alertID/status' is used
+  -external.label array
+    	Optional label in the form 'name=value' to add to all generated recording rules and alerts. Pass multiple -label flags in order to add multiple label sets.
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -external.url string
+    	External URL is used as alert's source for sent alerts to the notifier
+  -fs.disableMmap
+    	Whether to use pread() instead of mmap() for reading data files. By default mmap() is used for 64-bit arches and pread() is used for 32-bit arches, since they cannot read data files bigger than 2^32 bytes in memory. mmap() is usually faster for reading small data chunks than pread()
+  -http.connTimeout duration
+    	Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem (default 2m0s)
+  -http.disableResponseCompression
+    	Disable compression of HTTP responses to save CPU resources. By default compression is enabled to save network bandwidth
+  -http.idleConnTimeout duration
+    	Timeout for incoming idle http connections (default 1m0s)
+  -http.maxGracefulShutdownDuration duration
+    	The maximum duration for a graceful shutdown of the HTTP server. A highly loaded server may require increased value for a graceful shutdown (default 7s)
+  -http.pathPrefix string
+    	An optional prefix to add to all the paths handled by http server. For example, if '-http.pathPrefix=/foo/bar' is set, then all the http requests will be handled on '/foo/bar/*' paths. This may be useful for proxied requests. See https://www.robustperception.io/using-external-urls-and-proxies-with-prometheus
+  -http.shutdownDelay duration
+    	Optional delay before http server shutdown. During this delay, the server returns non-OK responses from /health page, so load balancers can route new requests to other servers
+  -httpAuth.password string
+    	Password for HTTP Basic Auth. The authentication is disabled if -httpAuth.username is empty
+  -httpAuth.username string
+    	Username for HTTP Basic Auth. The authentication is disabled if empty. See also -httpAuth.password
+  -httpListenAddr string
+    	Address to listen for http connections (default ":8880")
+  -loggerDisableTimestamps
+    	Whether to disable writing timestamps in logs
+  -loggerErrorsPerSecondLimit int
+    	Per-second limit on the number of ERROR messages. If more than the given number of errors are emitted per second, the remaining errors are suppressed. Zero values disable the rate limit
+  -loggerFormat string
+    	Format for logs. Possible values: default, json (default "default")
+  -loggerLevel string
+    	Minimum level of errors to log. Possible values: INFO, WARN, ERROR, FATAL, PANIC (default "INFO")
+  -loggerOutput string
+    	Output for the logs. Supported values: stderr, stdout (default "stderr")
+  -loggerTimezone string
+    	Timezone to use for timestamps in logs. Timezone must be a valid IANA Time Zone. For example: America/New_York, Europe/Berlin, Etc/GMT+3 or Local (default "UTC")
+  -loggerWarnsPerSecondLimit int
+    	Per-second limit on the number of WARN messages. If more than the given number of warns are emitted per second, then the remaining warns are suppressed. Zero values disable the rate limit
+  -memory.allowedBytes size
+    	Allowed size of system memory VictoriaMetrics caches may occupy. This option overrides -memory.allowedPercent if set to a non-zero value. Too low a value may increase the cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from OS page cache resulting in higher disk IO usage
+    	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 0)
+  -memory.allowedPercent float
+    	Allowed percent of system memory VictoriaMetrics caches may occupy. See also -memory.allowedBytes. Too low a value may increase cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from OS page cache which will result in higher disk IO usage (default 60)
+  -metricsAuthKey string
+    	Auth key for /metrics. It overrides httpAuth settings
+  -notifier.basicAuth.password array
+    	Optional basic auth password for -notifier.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -notifier.basicAuth.username array
+    	Optional basic auth username for -notifier.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -notifier.tlsCAFile array
+    	Optional path to TLS CA file to use for verifying connections to -notifier.url. By default system CA is used
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -notifier.tlsCertFile array
+    	Optional path to client-side TLS certificate file to use when connecting to -notifier.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -notifier.tlsInsecureSkipVerify array
+    	Whether to skip tls verification when connecting to -notifier.url
+    	Supports array of values separated by comma or specified via multiple flags.
+  -notifier.tlsKeyFile array
+    	Optional path to client-side TLS certificate key to use when connecting to -notifier.url
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -notifier.tlsServerName array
+    	Optional TLS server name to use for connections to -notifier.url. By default the server name from -notifier.url is used
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -notifier.url array
+    	Prometheus alertmanager URL. Required parameter. e.g. http://127.0.0.1:9093
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -pprofAuthKey string
+    	Auth key for /debug/pprof. It overrides httpAuth settings
+  -remoteRead.basicAuth.password string
+    	Optional basic auth password for -remoteRead.url
+  -remoteRead.basicAuth.passwordFile string
+    	Optional path to basic auth password to use for -remoteRead.url
+  -remoteRead.basicAuth.username string
+    	Optional basic auth username for -remoteRead.url
+  -remoteRead.bearerToken string
+    	Optional bearer auth token to use for -remoteRead.url.
+  -remoteRead.bearerTokenFile string
+    	Optional path to bearer token file to use for -remoteRead.url.
+  -remoteRead.ignoreRestoreErrors
+    	Whether to ignore errors from remote storage when restoring alerts state on startup. (default true)
+  -remoteRead.lookback duration
+    	Lookback defines how far to look into past for alerts timeseries. For example, if lookback=1h then range from now() to now()-1h will be scanned. (default 1h0m0s)
+  -remoteRead.tlsCAFile string
+    	Optional path to TLS CA file to use for verifying connections to -remoteRead.url. By default system CA is used
+  -remoteRead.tlsCertFile string
+    	Optional path to client-side TLS certificate file to use when connecting to -remoteRead.url
+  -remoteRead.tlsInsecureSkipVerify
+    	Whether to skip tls verification when connecting to -remoteRead.url
+  -remoteRead.tlsKeyFile string
+    	Optional path to client-side TLS certificate key to use when connecting to -remoteRead.url
+  -remoteRead.tlsServerName string
+    	Optional TLS server name to use for connections to -remoteRead.url. By default the server name from -remoteRead.url is used
+  -remoteRead.url vmalert
+    	Optional URL to VictoriaMetrics or vmselect that will be used to restore alerts state. This configuration makes sense only if vmalert was configured with `remoteWrite.url` before and has been successfully persisted its state. E.g. http://127.0.0.1:8428
+  -remoteWrite.basicAuth.password string
+    	Optional basic auth password for -remoteWrite.url
+  -remoteWrite.basicAuth.passwordFile string
+    	Optional path to basic auth password to use for -remoteWrite.url
+  -remoteWrite.basicAuth.username string
+    	Optional basic auth username for -remoteWrite.url
+  -remoteWrite.bearerToken string
+    	Optional bearer auth token to use for -remoteWrite.url.
+  -remoteWrite.bearerTokenFile string
+    	Optional path to bearer token file to use for -remoteWrite.url.
+  -remoteWrite.concurrency int
+    	Defines number of writers for concurrent writing into remote querier (default 1)
+  -remoteWrite.disablePathAppend
+    	Whether to disable automatic appending of '/api/v1/write' path to the configured -remoteWrite.url.
+  -remoteWrite.flushInterval duration
+    	Defines interval of flushes to remote write endpoint (default 5s)
+  -remoteWrite.maxBatchSize int
+    	Defines defines max number of timeseries to be flushed at once (default 1000)
+  -remoteWrite.maxQueueSize int
+    	Defines the max number of pending datapoints to remote write endpoint (default 100000)
+  -remoteWrite.tlsCAFile string
+    	Optional path to TLS CA file to use for verifying connections to -remoteWrite.url. By default system CA is used
+  -remoteWrite.tlsCertFile string
+    	Optional path to client-side TLS certificate file to use when connecting to -remoteWrite.url
+  -remoteWrite.tlsInsecureSkipVerify
+    	Whether to skip tls verification when connecting to -remoteWrite.url
+  -remoteWrite.tlsKeyFile string
+    	Optional path to client-side TLS certificate key to use when connecting to -remoteWrite.url
+  -remoteWrite.tlsServerName string
+    	Optional TLS server name to use for connections to -remoteWrite.url. By default the server name from -remoteWrite.url is used
+  -remoteWrite.url string
+    	Optional URL to VictoriaMetrics or vminsert where to persist alerts state and recording rules results in form of timeseries. For example, if -remoteWrite.url=http://127.0.0.1:8428 is specified, then the alerts state will be written to http://127.0.0.1:8428/api/v1/write . See also -remoteWrite.disablePathAppend
+  -replay.maxDatapointsPerQuery int
+    	Max number of data points expected in one request. The higher the value, the less requests will be made during replay. (default 1000)
+  -replay.ruleRetryAttempts int
+    	Defines how many retries to make before giving up on rule if request for it returns an error. (default 5)
+  -replay.rulesDelay duration
+    	Delay between rules evaluation within the group. Could be important if there are chained rules inside of the groupand processing need to wait for previous rule results to be persisted by remote storage before evaluating the next rule.Keep it equal or bigger than -remoteWrite.flushInterval. (default 1s)
+  -replay.timeFrom string
+    	The time filter in RFC3339 format to select time series with timestamp equal or higher than provided value. E.g. '2020-01-01T20:07:00Z'
+  -replay.timeTo string
+    	The time filter in RFC3339 format to select timeseries with timestamp equal or lower than provided value. E.g. '2020-01-01T20:07:00Z'
+  -rule array
+    	Path to the file with alert rules.
+    	Supports patterns. Flag can be specified multiple times.
+    	Examples:
+    	 -rule="/path/to/file". Path to a single file with alerting rules
+    	 -rule="dir/*.yaml" -rule="/*.yaml". Relative path to all .yaml files in "dir" folder,
+    	absolute path to all .yaml files in root.
+    	Rule files may contain %{ENV_VAR} placeholders, which are substituted by the corresponding env vars.
+    	Supports an array of values separated by comma or specified via multiple flags.
+  -rule.configCheckInterval duration
+    	Interval for checking for changes in '-rule' files. By default the checking is disabled. Send SIGHUP signal in order to force config check for changes
+  -rule.maxResolveDuration duration
+    	Limits the maximum duration for automatic alert expiration, which is by default equal to 3 evaluation intervals of the parent group.
+  -rule.validateExpressions
+    	Whether to validate rules expressions via MetricsQL engine (default true)
+  -rule.validateTemplates
+    	Whether to validate annotation and label templates (default true)
+  -tls
+    	Whether to enable TLS (aka HTTPS) for incoming requests. -tlsCertFile and -tlsKeyFile must be set if -tls is set
+  -tlsCertFile string
+    	Path to file with TLS certificate. Used only if -tls is set. Prefer ECDSA certs instead of RSA certs as RSA certs are slower
+  -tlsKeyFile string
+    	Path to file with TLS key. Used only if -tls is set
+  -version
+    	Show VictoriaMetrics version
+```
+
+`vmalert` supports "hot" config reload via the following methods:
+* send SIGHUP signal to `vmalert` process;
+* send GET request to `/-/reload` endpoint;
+* configure `-rule.configCheckInterval` flag for periodic reload
+on config change.
+
+## Contributing
+
+`vmalert` is mostly designed and built by VictoriaMetrics community.
+Feel free to share your experience and ideas for improving this
+software. Please keep simplicity as the main priority.
+
+## How to build from sources
+
+It is recommended using
+[binary releases](https://github.com/VictoriaMetrics/VictoriaMetrics/releases)
+- `vmalert` is located in `vmutils-*` archives there.
+
+
+### Development build
+
+1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.16.
+2. Run `make vmalert` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
+   It builds `vmalert` binary and puts it into the `bin` folder.
+
+### Production build
+
+1. [Install docker](https://docs.docker.com/install/).
+2. Run `make vmalert-prod` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
+   It builds `vmalert-prod` binary and puts it into the `bin` folder.
+
+
+### ARM build
+
+ARM build may run on Raspberry Pi or on [energy-efficient ARM servers](https://blog.cloudflare.com/arm-takes-wing/).
+
+### Development ARM build
+
+1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.16.
+2. Run `make vmalert-arm` or `make vmalert-arm64` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
+   It builds `vmalert-arm` or `vmalert-arm64` binary respectively and puts it into the `bin` folder.
+
+### Production ARM build
+
+1. [Install docker](https://docs.docker.com/install/).
+2. Run `make vmalert-arm-prod` or `make vmalert-arm64-prod` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
+   It builds `vmalert-arm-prod` or `vmalert-arm64-prod` binary respectively and puts it into the `bin` folder.

app/vmalert/alerting.go

@@ -0,0 +1,531 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"hash/fnv"
+	"sort"
+	"strconv"
+	"sync"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+// AlertingRule is basic alert entity
+type AlertingRule struct {
+	Type         datasource.Type
+	RuleID       uint64
+	Name         string
+	Expr         string
+	For          time.Duration
+	Labels       map[string]string
+	Annotations  map[string]string
+	GroupID      uint64
+	GroupName    string
+	EvalInterval time.Duration
+
+	q datasource.Querier
+
+	// guard status fields
+	mu sync.RWMutex
+	// stores list of active alerts
+	alerts map[uint64]*notifier.Alert
+	// stores last moment of time Exec was called
+	lastExecTime time.Time
+	// stores last error that happened in Exec func
+	// resets on every successful Exec
+	// may be used as Health state
+	lastExecError error
+	// stores the number of samples returned during
+	// the last evaluation
+	lastExecSamples int
+
+	metrics *alertingRuleMetrics
+}
+
+type alertingRuleMetrics struct {
+	errors  *gauge
+	pending *gauge
+	active  *gauge
+	samples *gauge
+}
+
+func newAlertingRule(qb datasource.QuerierBuilder, group *Group, cfg config.Rule) *AlertingRule {
+	ar := &AlertingRule{
+		Type:         cfg.Type,
+		RuleID:       cfg.ID,
+		Name:         cfg.Alert,
+		Expr:         cfg.Expr,
+		For:          cfg.For.Duration(),
+		Labels:       cfg.Labels,
+		Annotations:  cfg.Annotations,
+		GroupID:      group.ID(),
+		GroupName:    group.Name,
+		EvalInterval: group.Interval,
+		q: qb.BuildWithParams(datasource.QuerierParams{
+			DataSourceType:     &cfg.Type,
+			EvaluationInterval: group.Interval,
+			ExtraLabels:        group.ExtraFilterLabels,
+		}),
+		alerts:  make(map[uint64]*notifier.Alert),
+		metrics: &alertingRuleMetrics{},
+	}
+
+	labels := fmt.Sprintf(`alertname=%q, group=%q, id="%d"`, ar.Name, group.Name, ar.ID())
+	ar.metrics.pending = getOrCreateGauge(fmt.Sprintf(`vmalert_alerts_pending{%s}`, labels),
+		func() float64 {
+			ar.mu.RLock()
+			defer ar.mu.RUnlock()
+			var num int
+			for _, a := range ar.alerts {
+				if a.State == notifier.StatePending {
+					num++
+				}
+			}
+			return float64(num)
+		})
+	ar.metrics.active = getOrCreateGauge(fmt.Sprintf(`vmalert_alerts_firing{%s}`, labels),
+		func() float64 {
+			ar.mu.RLock()
+			defer ar.mu.RUnlock()
+			var num int
+			for _, a := range ar.alerts {
+				if a.State == notifier.StateFiring {
+					num++
+				}
+			}
+			return float64(num)
+		})
+	ar.metrics.errors = getOrCreateGauge(fmt.Sprintf(`vmalert_alerting_rules_error{%s}`, labels),
+		func() float64 {
+			ar.mu.RLock()
+			defer ar.mu.RUnlock()
+			if ar.lastExecError == nil {
+				return 0
+			}
+			return 1
+		})
+	ar.metrics.samples = getOrCreateGauge(fmt.Sprintf(`vmalert_alerting_rules_last_evaluation_samples{%s}`, labels),
+		func() float64 {
+			ar.mu.RLock()
+			defer ar.mu.RUnlock()
+			return float64(ar.lastExecSamples)
+		})
+	return ar
+}
+
+// Close unregisters rule metrics
+func (ar *AlertingRule) Close() {
+	metrics.UnregisterMetric(ar.metrics.active.name)
+	metrics.UnregisterMetric(ar.metrics.pending.name)
+	metrics.UnregisterMetric(ar.metrics.errors.name)
+	metrics.UnregisterMetric(ar.metrics.samples.name)
+}
+
+// String implements Stringer interface
+func (ar *AlertingRule) String() string {
+	return ar.Name
+}
+
+// ID returns unique Rule ID
+// within the parent Group.
+func (ar *AlertingRule) ID() uint64 {
+	return ar.RuleID
+}
+
+// ExecRange executes alerting rule on the given time range similarly to Exec.
+// It doesn't update internal states of the Rule and meant to be used just
+// to get time series for backfilling.
+// It returns ALERT and ALERT_FOR_STATE time series as result.
+func (ar *AlertingRule) ExecRange(ctx context.Context, start, end time.Time) ([]prompbmarshal.TimeSeries, error) {
+	series, err := ar.q.QueryRange(ctx, ar.Expr, start, end)
+	if err != nil {
+		return nil, err
+	}
+	var result []prompbmarshal.TimeSeries
+	qFn := func(query string) ([]datasource.Metric, error) {
+		return nil, fmt.Errorf("`query` template isn't supported in replay mode")
+	}
+	for _, s := range series {
+		// extra labels could contain templates, so we expand them first
+		labels, err := expandLabels(s, qFn, ar)
+		if err != nil {
+			return nil, fmt.Errorf("failed to expand labels: %s", err)
+		}
+		for k, v := range labels {
+			// apply extra labels to datasource
+			// so the hash key will be consistent on restore
+			s.SetLabel(k, v)
+		}
+
+		a, err := ar.newAlert(s, time.Time{}, qFn) // initial alert
+		if err != nil {
+			return nil, fmt.Errorf("failed to create alert: %s", err)
+		}
+		if ar.For == 0 { // if alert is instant
+			a.State = notifier.StateFiring
+			for i := range s.Values {
+				result = append(result, ar.alertToTimeSeries(a, s.Timestamps[i])...)
+			}
+			continue
+		}
+
+		// if alert with For > 0
+		prevT := time.Time{}
+		//activeAt := time.Time{}
+		for i := range s.Values {
+			at := time.Unix(s.Timestamps[i], 0)
+			if at.Sub(prevT) > ar.EvalInterval {
+				// reset to Pending if there are gaps > EvalInterval between DPs
+				a.State = notifier.StatePending
+				//activeAt = at
+				a.Start = at
+			} else if at.Sub(a.Start) >= ar.For {
+				a.State = notifier.StateFiring
+			}
+			prevT = at
+			result = append(result, ar.alertToTimeSeries(a, s.Timestamps[i])...)
+		}
+	}
+	return result, nil
+}
+
+// Exec executes AlertingRule expression via the given Querier.
+// Based on the Querier results AlertingRule maintains notifier.Alerts
+func (ar *AlertingRule) Exec(ctx context.Context) ([]prompbmarshal.TimeSeries, error) {
+	qMetrics, err := ar.q.Query(ctx, ar.Expr)
+	ar.mu.Lock()
+	defer ar.mu.Unlock()
+
+	ar.lastExecError = err
+	ar.lastExecTime = time.Now()
+	ar.lastExecSamples = len(qMetrics)
+	if err != nil {
+		return nil, fmt.Errorf("failed to execute query %q: %w", ar.Expr, err)
+	}
+
+	for h, a := range ar.alerts {
+		// cleanup inactive alerts from previous Exec
+		if a.State == notifier.StateInactive {
+			delete(ar.alerts, h)
+		}
+	}
+
+	qFn := func(query string) ([]datasource.Metric, error) { return ar.q.Query(ctx, query) }
+	updated := make(map[uint64]struct{})
+	// update list of active alerts
+	for _, m := range qMetrics {
+		// extra labels could contain templates, so we expand them first
+		labels, err := expandLabels(m, qFn, ar)
+		if err != nil {
+			return nil, fmt.Errorf("failed to expand labels: %s", err)
+		}
+		for k, v := range labels {
+			// apply extra labels to datasource
+			// so the hash key will be consistent on restore
+			m.SetLabel(k, v)
+		}
+		h := hash(m)
+		if _, ok := updated[h]; ok {
+			// duplicate may be caused by extra labels
+			// conflicting with the metric labels
+			return nil, fmt.Errorf("labels %v: %w", m.Labels, errDuplicate)
+		}
+		updated[h] = struct{}{}
+		if a, ok := ar.alerts[h]; ok {
+			if a.Value != m.Values[0] {
+				// update Value field with latest value
+				a.Value = m.Values[0]
+				// and re-exec template since Value can be used
+				// in annotations
+				a.Annotations, err = a.ExecTemplate(qFn, ar.Annotations)
+				if err != nil {
+					return nil, err
+				}
+			}
+			continue
+		}
+		a, err := ar.newAlert(m, ar.lastExecTime, qFn)
+		if err != nil {
+			ar.lastExecError = err
+			return nil, fmt.Errorf("failed to create alert: %w", err)
+		}
+		a.ID = h
+		a.State = notifier.StatePending
+		ar.alerts[h] = a
+	}
+
+	for h, a := range ar.alerts {
+		// if alert wasn't updated in this iteration
+		// means it is resolved already
+		if _, ok := updated[h]; !ok {
+			if a.State == notifier.StatePending {
+				// alert was in Pending state - it is not
+				// active anymore
+				delete(ar.alerts, h)
+				continue
+			}
+			a.State = notifier.StateInactive
+			continue
+		}
+		if a.State == notifier.StatePending && time.Since(a.Start) >= ar.For {
+			a.State = notifier.StateFiring
+			alertsFired.Inc()
+		}
+	}
+	return ar.toTimeSeries(ar.lastExecTime.Unix()), nil
+}
+
+func expandLabels(m datasource.Metric, q notifier.QueryFn, ar *AlertingRule) (map[string]string, error) {
+	metricLabels := make(map[string]string)
+	for _, l := range m.Labels {
+		metricLabels[l.Name] = l.Value
+	}
+	tpl := notifier.AlertTplData{
+		Labels: metricLabels,
+		Value:  m.Values[0],
+		Expr:   ar.Expr,
+	}
+	return notifier.ExecTemplate(q, ar.Labels, tpl)
+}
+
+func (ar *AlertingRule) toTimeSeries(timestamp int64) []prompbmarshal.TimeSeries {
+	var tss []prompbmarshal.TimeSeries
+	for _, a := range ar.alerts {
+		if a.State == notifier.StateInactive {
+			continue
+		}
+		ts := ar.alertToTimeSeries(a, timestamp)
+		tss = append(tss, ts...)
+	}
+	return tss
+}
+
+// UpdateWith copies all significant fields.
+// alerts state isn't copied since
+// it should be updated in next 2 Execs
+func (ar *AlertingRule) UpdateWith(r Rule) error {
+	nr, ok := r.(*AlertingRule)
+	if !ok {
+		return fmt.Errorf("BUG: attempt to update alerting rule with wrong type %#v", r)
+	}
+	ar.Expr = nr.Expr
+	ar.For = nr.For
+	ar.Labels = nr.Labels
+	ar.Annotations = nr.Annotations
+	ar.EvalInterval = nr.EvalInterval
+	ar.q = nr.q
+	return nil
+}
+
+// TODO: consider hashing algorithm in VM
+func hash(m datasource.Metric) uint64 {
+	hash := fnv.New64a()
+	labels := m.Labels
+	sort.Slice(labels, func(i, j int) bool {
+		return labels[i].Name < labels[j].Name
+	})
+	for _, l := range labels {
+		// drop __name__ to be consistent with Prometheus alerting
+		if l.Name == "__name__" {
+			continue
+		}
+		hash.Write([]byte(l.Name))
+		hash.Write([]byte(l.Value))
+		hash.Write([]byte("\xff"))
+	}
+	return hash.Sum64()
+}
+
+func (ar *AlertingRule) newAlert(m datasource.Metric, start time.Time, qFn notifier.QueryFn) (*notifier.Alert, error) {
+	a := &notifier.Alert{
+		GroupID: ar.GroupID,
+		Name:    ar.Name,
+		Labels:  map[string]string{},
+		Value:   m.Values[0],
+		Start:   start,
+		Expr:    ar.Expr,
+	}
+	// label defined here to make override possible by
+	// time series labels.
+	if !*disableAlertGroupLabel && ar.GroupName != "" {
+		a.Labels[alertGroupNameLabel] = ar.GroupName
+	}
+	for _, l := range m.Labels {
+		// drop __name__ to be consistent with Prometheus alerting
+		if l.Name == "__name__" {
+			continue
+		}
+		a.Labels[l.Name] = l.Value
+	}
+	var err error
+	a.Annotations, err = a.ExecTemplate(qFn, ar.Annotations)
+	return a, err
+}
+
+// AlertAPI generates APIAlert object from alert by its id(hash)
+func (ar *AlertingRule) AlertAPI(id uint64) *APIAlert {
+	ar.mu.RLock()
+	defer ar.mu.RUnlock()
+	a, ok := ar.alerts[id]
+	if !ok {
+		return nil
+	}
+	return ar.newAlertAPI(*a)
+}
+
+// RuleAPI returns Rule representation in form
+// of APIAlertingRule
+func (ar *AlertingRule) RuleAPI() APIAlertingRule {
+	var lastErr string
+	if ar.lastExecError != nil {
+		lastErr = ar.lastExecError.Error()
+	}
+	return APIAlertingRule{
+		// encode as strings to avoid rounding
+		ID:          fmt.Sprintf("%d", ar.ID()),
+		GroupID:     fmt.Sprintf("%d", ar.GroupID),
+		Type:        ar.Type.String(),
+		Name:        ar.Name,
+		Expression:  ar.Expr,
+		For:         ar.For.String(),
+		LastError:   lastErr,
+		LastSamples: ar.lastExecSamples,
+		LastExec:    ar.lastExecTime,
+		Labels:      ar.Labels,
+		Annotations: ar.Annotations,
+	}
+}
+
+// AlertsAPI generates list of APIAlert objects from existing alerts
+func (ar *AlertingRule) AlertsAPI() []*APIAlert {
+	var alerts []*APIAlert
+	ar.mu.RLock()
+	for _, a := range ar.alerts {
+		alerts = append(alerts, ar.newAlertAPI(*a))
+	}
+	ar.mu.RUnlock()
+	return alerts
+}
+
+func (ar *AlertingRule) newAlertAPI(a notifier.Alert) *APIAlert {
+	return &APIAlert{
+		// encode as strings to avoid rounding
+		ID:      fmt.Sprintf("%d", a.ID),
+		GroupID: fmt.Sprintf("%d", a.GroupID),
+		RuleID:  fmt.Sprintf("%d", ar.RuleID),
+
+		Name:        a.Name,
+		Expression:  ar.Expr,
+		Labels:      a.Labels,
+		Annotations: a.Annotations,
+		State:       a.State.String(),
+		ActiveAt:    a.Start,
+		Value:       strconv.FormatFloat(a.Value, 'f', -1, 32),
+	}
+}
+
+const (
+	// alertMetricName is the metric name for synthetic alert timeseries.
+	alertMetricName = "ALERTS"
+	// alertForStateMetricName is the metric name for 'for' state of alert.
+	alertForStateMetricName = "ALERTS_FOR_STATE"
+
+	// alertNameLabel is the label name indicating the name of an alert.
+	alertNameLabel = "alertname"
+	// alertStateLabel is the label name indicating the state of an alert.
+	alertStateLabel = "alertstate"
+
+	// alertGroupNameLabel defines the label name attached for generated time series.
+	alertGroupNameLabel = "alertgroup"
+)
+
+// alertToTimeSeries converts the given alert with the given timestamp to timeseries
+func (ar *AlertingRule) alertToTimeSeries(a *notifier.Alert, timestamp int64) []prompbmarshal.TimeSeries {
+	var tss []prompbmarshal.TimeSeries
+	tss = append(tss, alertToTimeSeries(ar.Name, a, timestamp))
+	if ar.For > 0 {
+		tss = append(tss, alertForToTimeSeries(ar.Name, a, timestamp))
+	}
+	return tss
+}
+
+func alertToTimeSeries(name string, a *notifier.Alert, timestamp int64) prompbmarshal.TimeSeries {
+	labels := make(map[string]string)
+	for k, v := range a.Labels {
+		labels[k] = v
+	}
+	labels["__name__"] = alertMetricName
+	labels[alertNameLabel] = name
+	labels[alertStateLabel] = a.State.String()
+	return newTimeSeries([]float64{1}, []int64{timestamp}, labels)
+}
+
+// alertForToTimeSeries returns a timeseries that represents
+// state of active alerts, where value is time when alert become active
+func alertForToTimeSeries(name string, a *notifier.Alert, timestamp int64) prompbmarshal.TimeSeries {
+	labels := make(map[string]string)
+	for k, v := range a.Labels {
+		labels[k] = v
+	}
+	labels["__name__"] = alertForStateMetricName
+	labels[alertNameLabel] = name
+	return newTimeSeries([]float64{float64(a.Start.Unix())}, []int64{timestamp}, labels)
+}
+
+// Restore restores the state of active alerts basing on previously written timeseries.
+// Restore restores only Start field. Field State will be always Pending and supposed
+// to be updated on next Exec, as well as Value field.
+// Only rules with For > 0 will be restored.
+func (ar *AlertingRule) Restore(ctx context.Context, q datasource.Querier, lookback time.Duration, labels map[string]string) error {
+	if q == nil {
+		return fmt.Errorf("querier is nil")
+	}
+
+	qFn := func(query string) ([]datasource.Metric, error) { return ar.q.Query(ctx, query) }
+
+	// account for external labels in filter
+	var labelsFilter string
+	for k, v := range labels {
+		labelsFilter += fmt.Sprintf(",%s=%q", k, v)
+	}
+
+	// Get the last data point in range via MetricsQL `last_over_time`.
+	// We don't use plain PromQL since Prometheus doesn't support
+	// remote write protocol which is used for state persistence in vmalert.
+	expr := fmt.Sprintf("last_over_time(%s{alertname=%q%s}[%ds])",
+		alertForStateMetricName, ar.Name, labelsFilter, int(lookback.Seconds()))
+	qMetrics, err := q.Query(ctx, expr)
+	if err != nil {
+		return err
+	}
+
+	for _, m := range qMetrics {
+		labels := m.Labels
+		m.Labels = make([]datasource.Label, 0)
+		// drop all extra labels, so hash key will
+		// be identical to time series received in Exec
+		for _, l := range labels {
+			if l.Name == alertNameLabel || l.Name == alertGroupNameLabel {
+				continue
+			}
+			m.Labels = append(m.Labels, l)
+		}
+
+		a, err := ar.newAlert(m, time.Unix(int64(m.Values[0]), 0), qFn)
+		if err != nil {
+			return fmt.Errorf("failed to create alert: %w", err)
+		}
+		a.ID = hash(m)
+		a.State = notifier.StatePending
+		ar.alerts[a.ID] = a
+		logger.Infof("alert %q (%d) restored to state at %v", a.Name, a.ID, a.Start)
+	}
+	return nil
+}

app/vmalert/alerting_test.go

@@ -0,0 +1,743 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"reflect"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+)
+
+func TestAlertingRule_ToTimeSeries(t *testing.T) {
+	timestamp := time.Now()
+	testCases := []struct {
+		rule  *AlertingRule
+		alert *notifier.Alert
+		expTS []prompbmarshal.TimeSeries
+	}{
+		{
+			newTestAlertingRule("instant", 0),
+			&notifier.Alert{State: notifier.StateFiring},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries([]float64{1}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__":      alertMetricName,
+					alertStateLabel: notifier.StateFiring.String(),
+					alertNameLabel:  "instant",
+				}),
+			},
+		},
+		{
+			newTestAlertingRule("instant extra labels", 0),
+			&notifier.Alert{State: notifier.StateFiring, Labels: map[string]string{
+				"job":      "foo",
+				"instance": "bar",
+			}},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries([]float64{1}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__":      alertMetricName,
+					alertStateLabel: notifier.StateFiring.String(),
+					alertNameLabel:  "instant extra labels",
+					"job":           "foo",
+					"instance":      "bar",
+				}),
+			},
+		},
+		{
+			newTestAlertingRule("instant labels override", 0),
+			&notifier.Alert{State: notifier.StateFiring, Labels: map[string]string{
+				alertStateLabel: "foo",
+				"__name__":      "bar",
+			}},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries([]float64{1}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__":      alertMetricName,
+					alertStateLabel: notifier.StateFiring.String(),
+					alertNameLabel:  "instant labels override",
+				}),
+			},
+		},
+		{
+			newTestAlertingRule("for", time.Second),
+			&notifier.Alert{State: notifier.StateFiring, Start: timestamp.Add(time.Second)},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries([]float64{1}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__":      alertMetricName,
+					alertStateLabel: notifier.StateFiring.String(),
+					alertNameLabel:  "for",
+				}),
+				newTimeSeries([]float64{float64(timestamp.Add(time.Second).Unix())},
+					[]int64{timestamp.UnixNano()},
+					map[string]string{
+						"__name__":     alertForStateMetricName,
+						alertNameLabel: "for",
+					}),
+			},
+		},
+		{
+			newTestAlertingRule("for pending", 10*time.Second),
+			&notifier.Alert{State: notifier.StatePending, Start: timestamp.Add(time.Second)},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries([]float64{1}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__":      alertMetricName,
+					alertStateLabel: notifier.StatePending.String(),
+					alertNameLabel:  "for pending",
+				}),
+				newTimeSeries([]float64{float64(timestamp.Add(time.Second).Unix())},
+					[]int64{timestamp.UnixNano()},
+					map[string]string{
+						"__name__":     alertForStateMetricName,
+						alertNameLabel: "for pending",
+					}),
+			},
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.rule.Name, func(t *testing.T) {
+			tc.rule.alerts[tc.alert.ID] = tc.alert
+			tss := tc.rule.toTimeSeries(timestamp.Unix())
+			if err := compareTimeSeries(t, tc.expTS, tss); err != nil {
+				t.Fatalf("timeseries missmatch: %s", err)
+			}
+		})
+	}
+}
+
+func TestAlertingRule_Exec(t *testing.T) {
+	const defaultStep = 5 * time.Millisecond
+	testCases := []struct {
+		rule      *AlertingRule
+		steps     [][]datasource.Metric
+		expAlerts map[uint64]*notifier.Alert
+	}{
+		{
+			newTestAlertingRule("empty", 0),
+			[][]datasource.Metric{},
+			map[uint64]*notifier.Alert{},
+		},
+		{
+			newTestAlertingRule("empty labels", 0),
+			[][]datasource.Metric{
+				{datasource.Metric{Values: []float64{1}, Timestamps: []int64{1}}},
+			},
+			map[uint64]*notifier.Alert{
+				hash(datasource.Metric{}): {State: notifier.StateFiring},
+			},
+		},
+		{
+			newTestAlertingRule("single-firing", 0),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo")): {State: notifier.StateFiring},
+			},
+		},
+		{
+			newTestAlertingRule("single-firing=>inactive", 0),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+				{},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo")): {State: notifier.StateInactive},
+			},
+		},
+		{
+			newTestAlertingRule("single-firing=>inactive=>firing", 0),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+				{},
+				{metricWithLabels(t, "name", "foo")},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo")): {State: notifier.StateFiring},
+			},
+		},
+		{
+			newTestAlertingRule("single-firing=>inactive=>firing=>inactive", 0),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+				{},
+				{metricWithLabels(t, "name", "foo")},
+				{},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo")): {State: notifier.StateInactive},
+			},
+		},
+		{
+			newTestAlertingRule("single-firing=>inactive=>firing=>inactive=>empty", 0),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+				{},
+				{metricWithLabels(t, "name", "foo")},
+				{},
+				{},
+			},
+			map[uint64]*notifier.Alert{},
+		},
+		{
+			newTestAlertingRule("single-firing=>inactive=>firing=>inactive=>empty=>firing", 0),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+				{},
+				{metricWithLabels(t, "name", "foo")},
+				{},
+				{},
+				{metricWithLabels(t, "name", "foo")},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo")): {State: notifier.StateFiring},
+			},
+		},
+		{
+			newTestAlertingRule("multiple-firing", 0),
+			[][]datasource.Metric{
+				{
+					metricWithLabels(t, "name", "foo"),
+					metricWithLabels(t, "name", "foo1"),
+					metricWithLabels(t, "name", "foo2"),
+				},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo")):  {State: notifier.StateFiring},
+				hash(metricWithLabels(t, "name", "foo1")): {State: notifier.StateFiring},
+				hash(metricWithLabels(t, "name", "foo2")): {State: notifier.StateFiring},
+			},
+		},
+		{
+			newTestAlertingRule("multiple-steps-firing", 0),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+				{metricWithLabels(t, "name", "foo1")},
+				{metricWithLabels(t, "name", "foo2")},
+			},
+			// 1: fire first alert
+			// 2: fire second alert, set first inactive
+			// 3: fire third alert, set second inactive, delete first one
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo1")): {State: notifier.StateInactive},
+				hash(metricWithLabels(t, "name", "foo2")): {State: notifier.StateFiring},
+			},
+		},
+		{
+			newTestAlertingRule("for-pending", time.Minute),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo")): {State: notifier.StatePending},
+			},
+		},
+		{
+			newTestAlertingRule("for-fired", defaultStep),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+				{metricWithLabels(t, "name", "foo")},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo")): {State: notifier.StateFiring},
+			},
+		},
+		{
+			newTestAlertingRule("for-pending=>empty", time.Second),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+				{metricWithLabels(t, "name", "foo")},
+				// empty step to reset and delete pending alerts
+				{},
+			},
+			map[uint64]*notifier.Alert{},
+		},
+		{
+			newTestAlertingRule("for-pending=>firing=>inactive", defaultStep),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+				{metricWithLabels(t, "name", "foo")},
+				// empty step to reset pending alerts
+				{},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo")): {State: notifier.StateInactive},
+			},
+		},
+		{
+			newTestAlertingRule("for-pending=>firing=>inactive=>pending", defaultStep),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+				{metricWithLabels(t, "name", "foo")},
+				// empty step to reset pending alerts
+				{},
+				{metricWithLabels(t, "name", "foo")},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo")): {State: notifier.StatePending},
+			},
+		},
+		{
+			newTestAlertingRule("for-pending=>firing=>inactive=>pending=>firing", defaultStep),
+			[][]datasource.Metric{
+				{metricWithLabels(t, "name", "foo")},
+				{metricWithLabels(t, "name", "foo")},
+				// empty step to reset pending alerts
+				{},
+				{metricWithLabels(t, "name", "foo")},
+				{metricWithLabels(t, "name", "foo")},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo")): {State: notifier.StateFiring},
+			},
+		},
+	}
+	fakeGroup := Group{Name: "TestRule_Exec"}
+	for _, tc := range testCases {
+		t.Run(tc.rule.Name, func(t *testing.T) {
+			fq := &fakeQuerier{}
+			tc.rule.q = fq
+			tc.rule.GroupID = fakeGroup.ID()
+			for _, step := range tc.steps {
+				fq.reset()
+				fq.add(step...)
+				if _, err := tc.rule.Exec(context.TODO()); err != nil {
+					t.Fatalf("unexpected err: %s", err)
+				}
+				// artificial delay between applying steps
+				time.Sleep(defaultStep)
+			}
+			if len(tc.rule.alerts) != len(tc.expAlerts) {
+				t.Fatalf("expected %d alerts; got %d", len(tc.expAlerts), len(tc.rule.alerts))
+			}
+			for key, exp := range tc.expAlerts {
+				got, ok := tc.rule.alerts[key]
+				if !ok {
+					t.Fatalf("expected to have key %d", key)
+				}
+				if got.State != exp.State {
+					t.Fatalf("expected state %d; got %d", exp.State, got.State)
+				}
+			}
+		})
+	}
+}
+
+func TestAlertingRule_ExecRange(t *testing.T) {
+	testCases := []struct {
+		rule      *AlertingRule
+		data      []datasource.Metric
+		expAlerts []*notifier.Alert
+	}{
+		{
+			newTestAlertingRule("empty", 0),
+			[]datasource.Metric{},
+			nil,
+		},
+		{
+			newTestAlertingRule("empty labels", 0),
+			[]datasource.Metric{
+				{Values: []float64{1}, Timestamps: []int64{1}},
+			},
+			[]*notifier.Alert{
+				{State: notifier.StateFiring},
+			},
+		},
+		{
+			newTestAlertingRule("single-firing", 0),
+			[]datasource.Metric{
+				metricWithLabels(t, "name", "foo"),
+			},
+			[]*notifier.Alert{
+				{
+					Labels: map[string]string{"name": "foo"},
+					State:  notifier.StateFiring,
+				},
+			},
+		},
+		{
+			newTestAlertingRule("single-firing-on-range", 0),
+			[]datasource.Metric{
+				{Values: []float64{1, 1, 1}, Timestamps: []int64{1e3, 2e3, 3e3}},
+			},
+			[]*notifier.Alert{
+				{State: notifier.StateFiring},
+				{State: notifier.StateFiring},
+				{State: notifier.StateFiring},
+			},
+		},
+		{
+			newTestAlertingRule("for-pending", time.Second),
+			[]datasource.Metric{
+				{Values: []float64{1, 1, 1}, Timestamps: []int64{1, 3, 5}},
+			},
+			[]*notifier.Alert{
+				{State: notifier.StatePending, Start: time.Unix(1, 0)},
+				{State: notifier.StatePending, Start: time.Unix(3, 0)},
+				{State: notifier.StatePending, Start: time.Unix(5, 0)},
+			},
+		},
+		{
+			newTestAlertingRule("for-firing", 3*time.Second),
+			[]datasource.Metric{
+				{Values: []float64{1, 1, 1}, Timestamps: []int64{1, 3, 5}},
+			},
+			[]*notifier.Alert{
+				{State: notifier.StatePending, Start: time.Unix(1, 0)},
+				{State: notifier.StatePending, Start: time.Unix(1, 0)},
+				{State: notifier.StateFiring, Start: time.Unix(1, 0)},
+			},
+		},
+		{
+			newTestAlertingRule("for=>pending=>firing=>pending=>firing=>pending", time.Second),
+			[]datasource.Metric{
+				{Values: []float64{1, 1, 1, 1, 1}, Timestamps: []int64{1, 2, 5, 6, 20}},
+			},
+			[]*notifier.Alert{
+				{State: notifier.StatePending, Start: time.Unix(1, 0)},
+				{State: notifier.StateFiring, Start: time.Unix(1, 0)},
+				{State: notifier.StatePending, Start: time.Unix(5, 0)},
+				{State: notifier.StateFiring, Start: time.Unix(5, 0)},
+				{State: notifier.StatePending, Start: time.Unix(20, 0)},
+			},
+		},
+		{
+			newTestAlertingRule("multi-series-for=>pending=>pending=>firing", 3*time.Second),
+			[]datasource.Metric{
+				{Values: []float64{1, 1, 1}, Timestamps: []int64{1, 3, 5}},
+				{Values: []float64{1, 1}, Timestamps: []int64{1, 5},
+					Labels: []datasource.Label{{Name: "foo", Value: "bar"}},
+				},
+			},
+			[]*notifier.Alert{
+				{State: notifier.StatePending, Start: time.Unix(1, 0)},
+				{State: notifier.StatePending, Start: time.Unix(1, 0)},
+				{State: notifier.StateFiring, Start: time.Unix(1, 0)},
+				//
+				{State: notifier.StatePending, Start: time.Unix(1, 0),
+					Labels: map[string]string{
+						"foo": "bar",
+					}},
+				{State: notifier.StatePending, Start: time.Unix(5, 0),
+					Labels: map[string]string{
+						"foo": "bar",
+					}},
+			},
+		},
+		{
+			newTestRuleWithLabels("multi-series-firing", "source", "vm"),
+			[]datasource.Metric{
+				{Values: []float64{1, 1}, Timestamps: []int64{1, 100}},
+				{Values: []float64{1, 1}, Timestamps: []int64{1, 5},
+					Labels: []datasource.Label{{Name: "foo", Value: "bar"}},
+				},
+			},
+			[]*notifier.Alert{
+				{State: notifier.StateFiring, Labels: map[string]string{
+					"source": "vm",
+				}},
+				{State: notifier.StateFiring, Labels: map[string]string{
+					"source": "vm",
+				}},
+				//
+				{State: notifier.StateFiring, Labels: map[string]string{
+					"foo":    "bar",
+					"source": "vm",
+				}},
+				{State: notifier.StateFiring, Labels: map[string]string{
+					"foo":    "bar",
+					"source": "vm",
+				}},
+			},
+		},
+	}
+	fakeGroup := Group{Name: "TestRule_ExecRange"}
+	for _, tc := range testCases {
+		t.Run(tc.rule.Name, func(t *testing.T) {
+			fq := &fakeQuerier{}
+			tc.rule.q = fq
+			tc.rule.GroupID = fakeGroup.ID()
+			fq.add(tc.data...)
+			gotTS, err := tc.rule.ExecRange(context.TODO(), time.Now(), time.Now())
+			if err != nil {
+				t.Fatalf("unexpected err: %s", err)
+			}
+			var expTS []prompbmarshal.TimeSeries
+			var j int
+			for _, series := range tc.data {
+				for _, timestamp := range series.Timestamps {
+					expTS = append(expTS, tc.rule.alertToTimeSeries(tc.expAlerts[j], timestamp)...)
+					j++
+				}
+			}
+			if len(gotTS) != len(expTS) {
+				t.Fatalf("expected %d time series; got %d", len(expTS), len(gotTS))
+			}
+			for i := range expTS {
+				got, exp := gotTS[i], expTS[i]
+				if !reflect.DeepEqual(got, exp) {
+					t.Fatalf("%d: expected \n%v but got \n%v", i, exp, got)
+				}
+			}
+		})
+	}
+}
+
+func TestAlertingRule_Restore(t *testing.T) {
+	testCases := []struct {
+		rule      *AlertingRule
+		metrics   []datasource.Metric
+		expAlerts map[uint64]*notifier.Alert
+	}{
+		{
+			newTestRuleWithLabels("no extra labels"),
+			[]datasource.Metric{
+				metricWithValueAndLabels(t, float64(time.Now().Truncate(time.Hour).Unix()),
+					"__name__", alertForStateMetricName,
+					alertNameLabel, "",
+				),
+			},
+			map[uint64]*notifier.Alert{
+				hash(datasource.Metric{}): {State: notifier.StatePending,
+					Start: time.Now().Truncate(time.Hour)},
+			},
+		},
+		{
+			newTestRuleWithLabels("metric labels"),
+			[]datasource.Metric{
+				metricWithValueAndLabels(t, float64(time.Now().Truncate(time.Hour).Unix()),
+					"__name__", alertForStateMetricName,
+					alertNameLabel, "",
+					alertGroupNameLabel, "groupID",
+					"foo", "bar",
+					"namespace", "baz",
+				),
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t,
+					"foo", "bar",
+					"namespace", "baz",
+				)): {State: notifier.StatePending,
+					Start: time.Now().Truncate(time.Hour)},
+			},
+		},
+		{
+			newTestRuleWithLabels("rule labels", "source", "vm"),
+			[]datasource.Metric{
+				metricWithValueAndLabels(t, float64(time.Now().Truncate(time.Hour).Unix()),
+					"__name__", alertForStateMetricName,
+					alertNameLabel, "",
+					"foo", "bar",
+					"namespace", "baz",
+					// extra labels set by rule
+					"source", "vm",
+				),
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t,
+					"foo", "bar",
+					"namespace", "baz",
+					"source", "vm",
+				)): {State: notifier.StatePending,
+					Start: time.Now().Truncate(time.Hour)},
+			},
+		},
+		{
+			newTestRuleWithLabels("multiple alerts"),
+			[]datasource.Metric{
+				metricWithValueAndLabels(t, float64(time.Now().Truncate(time.Hour).Unix()),
+					"__name__", alertForStateMetricName,
+					"host", "localhost-1",
+				),
+				metricWithValueAndLabels(t, float64(time.Now().Truncate(2*time.Hour).Unix()),
+					"__name__", alertForStateMetricName,
+					"host", "localhost-2",
+				),
+				metricWithValueAndLabels(t, float64(time.Now().Truncate(3*time.Hour).Unix()),
+					"__name__", alertForStateMetricName,
+					"host", "localhost-3",
+				),
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "host", "localhost-1")): {State: notifier.StatePending,
+					Start: time.Now().Truncate(time.Hour)},
+				hash(metricWithLabels(t, "host", "localhost-2")): {State: notifier.StatePending,
+					Start: time.Now().Truncate(2 * time.Hour)},
+				hash(metricWithLabels(t, "host", "localhost-3")): {State: notifier.StatePending,
+					Start: time.Now().Truncate(3 * time.Hour)},
+			},
+		},
+	}
+	fakeGroup := Group{Name: "TestRule_Exec"}
+	for _, tc := range testCases {
+		t.Run(tc.rule.Name, func(t *testing.T) {
+			fq := &fakeQuerier{}
+			tc.rule.GroupID = fakeGroup.ID()
+			tc.rule.q = fq
+			fq.add(tc.metrics...)
+			if err := tc.rule.Restore(context.TODO(), fq, time.Hour, nil); err != nil {
+				t.Fatalf("unexpected err: %s", err)
+			}
+			if len(tc.rule.alerts) != len(tc.expAlerts) {
+				t.Fatalf("expected %d alerts; got %d", len(tc.expAlerts), len(tc.rule.alerts))
+			}
+			for key, exp := range tc.expAlerts {
+				got, ok := tc.rule.alerts[key]
+				if !ok {
+					t.Fatalf("expected to have key %d", key)
+				}
+				if got.State != exp.State {
+					t.Fatalf("expected state %d; got %d", exp.State, got.State)
+				}
+				if got.Start != exp.Start {
+					t.Fatalf("expected Start %v; got %v", exp.Start, got.Start)
+				}
+			}
+		})
+	}
+}
+
+func TestAlertingRule_Exec_Negative(t *testing.T) {
+	fq := &fakeQuerier{}
+	ar := newTestAlertingRule("test", 0)
+	ar.Labels = map[string]string{"job": "test"}
+	ar.q = fq
+
+	// successful attempt
+	fq.add(metricWithValueAndLabels(t, 1, "__name__", "foo", "job", "bar"))
+	_, err := ar.Exec(context.TODO())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// label `job` will collide with rule extra label and will make both time series equal
+	fq.add(metricWithValueAndLabels(t, 1, "__name__", "foo", "job", "baz"))
+	_, err = ar.Exec(context.TODO())
+	if !errors.Is(err, errDuplicate) {
+		t.Fatalf("expected to have %s error; got %s", errDuplicate, err)
+	}
+
+	fq.reset()
+
+	expErr := "connection reset by peer"
+	fq.setErr(errors.New(expErr))
+	_, err = ar.Exec(context.TODO())
+	if err == nil {
+		t.Fatalf("expected to get err; got nil")
+	}
+	if !strings.Contains(err.Error(), expErr) {
+		t.Fatalf("expected to get err %q; got %q insterad", expErr, err)
+	}
+}
+
+func TestAlertingRule_Template(t *testing.T) {
+	testCases := []struct {
+		rule      *AlertingRule
+		metrics   []datasource.Metric
+		expAlerts map[uint64]*notifier.Alert
+	}{
+		{
+			newTestRuleWithLabels("common", "region", "east"),
+			[]datasource.Metric{
+				metricWithValueAndLabels(t, 1, "instance", "foo"),
+				metricWithValueAndLabels(t, 1, "instance", "bar"),
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "region", "east", "instance", "foo")): {
+					Annotations: map[string]string{},
+					Labels: map[string]string{
+						"region":   "east",
+						"instance": "foo",
+					},
+				},
+				hash(metricWithLabels(t, "region", "east", "instance", "bar")): {
+					Annotations: map[string]string{},
+					Labels: map[string]string{
+						"region":   "east",
+						"instance": "bar",
+					},
+				},
+			},
+		},
+		{
+			&AlertingRule{
+				Name: "override label",
+				Labels: map[string]string{
+					"instance": "{{ $labels.instance }}",
+					"region":   "east",
+				},
+				Annotations: map[string]string{
+					"summary":     `Too high connection number for "{{ $labels.instance }}" for region {{ $labels.region }}`,
+					"description": `It is {{ $value }} connections for "{{ $labels.instance }}"`,
+				},
+				alerts: make(map[uint64]*notifier.Alert),
+			},
+			[]datasource.Metric{
+				metricWithValueAndLabels(t, 2, "instance", "foo"),
+				metricWithValueAndLabels(t, 10, "instance", "bar"),
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "region", "east", "instance", "foo")): {
+					Labels: map[string]string{
+						"instance": "foo",
+						"region":   "east",
+					},
+					Annotations: map[string]string{
+						"summary":     `Too high connection number for "foo" for region east`,
+						"description": `It is 2 connections for "foo"`,
+					},
+				},
+				hash(metricWithLabels(t, "region", "east", "instance", "bar")): {
+					Labels: map[string]string{
+						"instance": "bar",
+						"region":   "east",
+					},
+					Annotations: map[string]string{
+						"summary":     `Too high connection number for "bar" for region east`,
+						"description": `It is 10 connections for "bar"`,
+					},
+				},
+			},
+		},
+	}
+	fakeGroup := Group{Name: "TestRule_Exec"}
+	for _, tc := range testCases {
+		t.Run(tc.rule.Name, func(t *testing.T) {
+			fq := &fakeQuerier{}
+			tc.rule.GroupID = fakeGroup.ID()
+			tc.rule.q = fq
+			fq.add(tc.metrics...)
+			if _, err := tc.rule.Exec(context.TODO()); err != nil {
+				t.Fatalf("unexpected err: %s", err)
+			}
+			for hash, expAlert := range tc.expAlerts {
+				gotAlert := tc.rule.alerts[hash]
+				if gotAlert == nil {
+					t.Fatalf("alert %d is missing; labels: %v; annotations: %v",
+						hash, expAlert.Labels, expAlert.Annotations)
+				}
+				if !reflect.DeepEqual(expAlert.Annotations, gotAlert.Annotations) {
+					t.Fatalf("expected to have annotations %#v; got %#v", expAlert.Annotations, gotAlert.Annotations)
+				}
+				if !reflect.DeepEqual(expAlert.Labels, gotAlert.Labels) {
+					t.Fatalf("expected to have labels %#v; got %#v", expAlert.Labels, gotAlert.Labels)
+				}
+			}
+		})
+	}
+}
+
+func newTestRuleWithLabels(name string, labels ...string) *AlertingRule {
+	r := newTestAlertingRule(name, 0)
+	r.Labels = make(map[string]string)
+	for i := 0; i < len(labels); i += 2 {
+		r.Labels[labels[i]] = labels[i+1]
+	}
+	return r
+}
+
+func newTestAlertingRule(name string, waitFor time.Duration) *AlertingRule {
+	return &AlertingRule{Name: name, alerts: make(map[uint64]*notifier.Alert), For: waitFor, EvalInterval: waitFor}
+}

app/vmalert/config/config.go

@@ -0,0 +1,270 @@
+package config
+
+import (
+	"crypto/md5"
+	"fmt"
+	"hash/fnv"
+	"io/ioutil"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envtemplate"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"gopkg.in/yaml.v2"
+)
+
+// Group contains list of Rules grouped into
+// entity with one name and evaluation interval
+type Group struct {
+	Type        datasource.Type `yaml:"type,omitempty"`
+	File        string
+	Name        string             `yaml:"name"`
+	Interval    utils.PromDuration `yaml:"interval"`
+	Rules       []Rule             `yaml:"rules"`
+	Concurrency int                `yaml:"concurrency"`
+	// ExtraFilterLabels is a list label filters applied to every rule
+	// request withing a group. Is compatible only with VM datasources.
+	// See https://docs.victoriametrics.com#prometheus-querying-api-enhancements
+	ExtraFilterLabels map[string]string `yaml:"extra_filter_labels"`
+	// Labels is a set of label value pairs, that will be added to every rule.
+	// It has priority over the external labels.
+	Labels map[string]string `yaml:"labels"`
+	// Checksum stores the hash of yaml definition for this group.
+	// May be used to detect any changes like rules re-ordering etc.
+	Checksum string
+
+	// Catches all undefined fields and must be empty after parsing.
+	XXX map[string]interface{} `yaml:",inline"`
+}
+
+// UnmarshalYAML implements the yaml.Unmarshaler interface.
+func (g *Group) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type group Group
+	if err := unmarshal((*group)(g)); err != nil {
+		return err
+	}
+	b, err := yaml.Marshal(g)
+	if err != nil {
+		return fmt.Errorf("failed to marshal group configuration for checksum: %w", err)
+	}
+	// change default value to prometheus datasource.
+	if g.Type.Get() == "" {
+		g.Type.Set(datasource.NewPrometheusType())
+	}
+	// update rules with empty type.
+	for i, r := range g.Rules {
+		if r.Type.Get() == "" {
+			r.Type.Set(g.Type)
+			r.ID = HashRule(r)
+			g.Rules[i] = r
+		}
+	}
+
+	h := md5.New()
+	h.Write(b)
+	g.Checksum = fmt.Sprintf("%x", h.Sum(nil))
+	return nil
+}
+
+// Validate check for internal Group or Rule configuration errors
+func (g *Group) Validate(validateAnnotations, validateExpressions bool) error {
+	if g.Name == "" {
+		return fmt.Errorf("group name must be set")
+	}
+	if len(g.Rules) == 0 {
+		return fmt.Errorf("group %q can't contain no rules", g.Name)
+	}
+
+	uniqueRules := map[uint64]struct{}{}
+	for _, r := range g.Rules {
+		ruleName := r.Record
+		if r.Alert != "" {
+			ruleName = r.Alert
+		}
+		if _, ok := uniqueRules[r.ID]; ok {
+			return fmt.Errorf("rule %q duplicate", ruleName)
+		}
+		uniqueRules[r.ID] = struct{}{}
+		if err := r.Validate(); err != nil {
+			return fmt.Errorf("invalid rule %q.%q: %w", g.Name, ruleName, err)
+		}
+		if validateExpressions {
+			// its needed only for tests.
+			// because correct types must be inherited after unmarshalling.
+			exprValidator := g.Type.ValidateExpr
+			if r.Type.Get() != "" {
+				exprValidator = r.Type.ValidateExpr
+			}
+			if err := exprValidator(r.Expr); err != nil {
+				return fmt.Errorf("invalid expression for rule %q.%q: %w", g.Name, ruleName, err)
+			}
+		}
+		if validateAnnotations {
+			if err := notifier.ValidateTemplates(r.Annotations); err != nil {
+				return fmt.Errorf("invalid annotations for rule %q.%q: %w", g.Name, ruleName, err)
+			}
+			if err := notifier.ValidateTemplates(r.Labels); err != nil {
+				return fmt.Errorf("invalid labels for rule %q.%q: %w", g.Name, ruleName, err)
+			}
+		}
+	}
+	return checkOverflow(g.XXX, fmt.Sprintf("group %q", g.Name))
+}
+
+// Rule describes entity that represent either
+// recording rule or alerting rule.
+type Rule struct {
+	ID          uint64
+	Type        datasource.Type    `yaml:"type,omitempty"`
+	Record      string             `yaml:"record,omitempty"`
+	Alert       string             `yaml:"alert,omitempty"`
+	Expr        string             `yaml:"expr"`
+	For         utils.PromDuration `yaml:"for"`
+	Labels      map[string]string  `yaml:"labels,omitempty"`
+	Annotations map[string]string  `yaml:"annotations,omitempty"`
+
+	// Catches all undefined fields and must be empty after parsing.
+	XXX map[string]interface{} `yaml:",inline"`
+}
+
+// UnmarshalYAML implements the yaml.Unmarshaler interface.
+func (r *Rule) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type rule Rule
+	if err := unmarshal((*rule)(r)); err != nil {
+		return err
+	}
+	r.ID = HashRule(*r)
+	return nil
+}
+
+// Name returns Rule name according to its type
+func (r *Rule) Name() string {
+	if r.Record != "" {
+		return r.Record
+	}
+	return r.Alert
+}
+
+// HashRule hashes significant Rule fields into
+// unique hash that supposed to define Rule uniqueness
+func HashRule(r Rule) uint64 {
+	h := fnv.New64a()
+	h.Write([]byte(r.Expr))
+	if r.Record != "" {
+		h.Write([]byte("recording"))
+		h.Write([]byte(r.Record))
+	} else {
+		h.Write([]byte("alerting"))
+		h.Write([]byte(r.Alert))
+	}
+	h.Write([]byte(r.Type.Get()))
+	kv := sortMap(r.Labels)
+	for _, i := range kv {
+		h.Write([]byte(i.key))
+		h.Write([]byte(i.value))
+		h.Write([]byte("\xff"))
+	}
+	return h.Sum64()
+}
+
+// Validate check for Rule configuration errors
+func (r *Rule) Validate() error {
+	if (r.Record == "" && r.Alert == "") || (r.Record != "" && r.Alert != "") {
+		return fmt.Errorf("either `record` or `alert` must be set")
+	}
+	if r.Expr == "" {
+		return fmt.Errorf("expression can't be empty")
+	}
+	return checkOverflow(r.XXX, "rule")
+}
+
+// Parse parses rule configs from given file patterns
+func Parse(pathPatterns []string, validateAnnotations, validateExpressions bool) ([]Group, error) {
+	var fp []string
+	for _, pattern := range pathPatterns {
+		matches, err := filepath.Glob(pattern)
+		if err != nil {
+			return nil, fmt.Errorf("error reading file pattern %s: %w", pattern, err)
+		}
+		fp = append(fp, matches...)
+	}
+	errGroup := new(utils.ErrGroup)
+	var groups []Group
+	for _, file := range fp {
+		uniqueGroups := map[string]struct{}{}
+		gr, err := parseFile(file)
+		if err != nil {
+			errGroup.Add(fmt.Errorf("failed to parse file %q: %w", file, err))
+			continue
+		}
+		for _, g := range gr {
+			if err := g.Validate(validateAnnotations, validateExpressions); err != nil {
+				errGroup.Add(fmt.Errorf("invalid group %q in file %q: %w", g.Name, file, err))
+				continue
+			}
+			if _, ok := uniqueGroups[g.Name]; ok {
+				errGroup.Add(fmt.Errorf("group name %q duplicate in file %q", g.Name, file))
+				continue
+			}
+			uniqueGroups[g.Name] = struct{}{}
+			g.File = file
+			groups = append(groups, g)
+		}
+	}
+	if err := errGroup.Err(); err != nil {
+		return nil, err
+	}
+	if len(groups) < 1 {
+		logger.Warnf("no groups found in %s", strings.Join(pathPatterns, ";"))
+	}
+	return groups, nil
+}
+
+func parseFile(path string) ([]Group, error) {
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("error reading alert rule file: %w", err)
+	}
+	data = envtemplate.Replace(data)
+	g := struct {
+		Groups []Group `yaml:"groups"`
+		// Catches all undefined fields and must be empty after parsing.
+		XXX map[string]interface{} `yaml:",inline"`
+	}{}
+	err = yaml.Unmarshal(data, &g)
+	if err != nil {
+		return nil, err
+	}
+	return g.Groups, checkOverflow(g.XXX, "config")
+}
+
+func checkOverflow(m map[string]interface{}, ctx string) error {
+	if len(m) > 0 {
+		var keys []string
+		for k := range m {
+			keys = append(keys, k)
+		}
+		return fmt.Errorf("unknown fields in %s: %s", ctx, strings.Join(keys, ", "))
+	}
+	return nil
+}
+
+type item struct {
+	key, value string
+}
+
+func sortMap(m map[string]string) []item {
+	var kv []item
+	for k, v := range m {
+		kv = append(kv, item{key: k, value: v})
+	}
+	sort.Slice(kv, func(i, j int) bool {
+		return kv[i].key < kv[j].key
+	})
+	return kv
+}

app/vmalert/config/config_test.go

@@ -0,0 +1,483 @@
+package config
+
+import (
+	"net/url"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+	"gopkg.in/yaml.v2"
+)
+
+func TestMain(m *testing.M) {
+	u, _ := url.Parse("https://victoriametrics.com/path")
+	notifier.InitTemplateFunc(u)
+	os.Exit(m.Run())
+}
+
+func TestParseGood(t *testing.T) {
+	if _, err := Parse([]string{"testdata/*good.rules", "testdata/dir/*good.*"}, true, true); err != nil {
+		t.Errorf("error parsing files %s", err)
+	}
+}
+
+func TestParseBad(t *testing.T) {
+	testCases := []struct {
+		path   []string
+		expErr string
+	}{
+		{
+			[]string{"testdata/rules0-bad.rules"},
+			"unexpected token",
+		},
+		{
+			[]string{"testdata/dir/rules0-bad.rules"},
+			"error parsing annotation",
+		},
+		{
+			[]string{"testdata/dir/rules1-bad.rules"},
+			"duplicate in file",
+		},
+		{
+			[]string{"testdata/dir/rules2-bad.rules"},
+			"function \"unknown\" not defined",
+		},
+		{
+			[]string{"testdata/dir/rules3-bad.rules"},
+			"either `record` or `alert` must be set",
+		},
+		{
+			[]string{"testdata/dir/rules4-bad.rules"},
+			"either `record` or `alert` must be set",
+		},
+		{
+			[]string{"testdata/rules1-bad.rules"},
+			"bad graphite expr",
+		},
+	}
+	for _, tc := range testCases {
+		_, err := Parse(tc.path, true, true)
+		if err == nil {
+			t.Errorf("expected to get error")
+			return
+		}
+		if !strings.Contains(err.Error(), tc.expErr) {
+			t.Errorf("expected err to contain %q; got %q instead", tc.expErr, err)
+		}
+	}
+}
+
+func TestRule_Validate(t *testing.T) {
+	if err := (&Rule{}).Validate(); err == nil {
+		t.Errorf("expected empty name error")
+	}
+	if err := (&Rule{Alert: "alert"}).Validate(); err == nil {
+		t.Errorf("expected empty expr error")
+	}
+	if err := (&Rule{Alert: "alert", Expr: "test>0"}).Validate(); err != nil {
+		t.Errorf("expected valid rule; got %s", err)
+	}
+}
+
+func TestGroup_Validate(t *testing.T) {
+	testCases := []struct {
+		group               *Group
+		rules               []Rule
+		validateAnnotations bool
+		validateExpressions bool
+		expErr              string
+	}{
+		{
+			group:  &Group{},
+			expErr: "group name must be set",
+		},
+		{
+			group:  &Group{Name: "test"},
+			expErr: "contain no rules",
+		},
+		{
+			group: &Group{Name: "test",
+				Rules: []Rule{
+					{
+						Record: "record",
+						Expr:   "up | 0",
+					},
+				},
+			},
+			expErr: "",
+		},
+		{
+			group: &Group{Name: "test",
+				Rules: []Rule{
+					{
+						Record: "record",
+						Expr:   "up | 0",
+					},
+				},
+			},
+			expErr:              "invalid expression",
+			validateExpressions: true,
+		},
+		{
+			group: &Group{Name: "test",
+				Rules: []Rule{
+					{
+						Alert: "alert",
+						Expr:  "up == 1",
+						Labels: map[string]string{
+							"summary": "{{ value|query }}",
+						},
+					},
+				},
+			},
+			expErr: "",
+		},
+		{
+			group: &Group{Name: "test",
+				Rules: []Rule{
+					{
+						Alert: "alert",
+						Expr:  "up == 1",
+						Labels: map[string]string{
+							"summary": `
+{{ with printf "node_memory_MemTotal{job='node',instance='%s'}" "localhost" | query }}
+  {{ . | first | value | humanize1024 }}B
+{{ end }}`,
+						},
+					},
+				},
+			},
+			validateAnnotations: true,
+		},
+		{
+			group: &Group{Name: "test",
+				Rules: []Rule{
+					{
+						Alert: "alert",
+						Expr:  "up == 1",
+					},
+					{
+						Alert: "alert",
+						Expr:  "up == 1",
+					},
+				},
+			},
+			expErr: "duplicate",
+		},
+		{
+			group: &Group{Name: "test",
+				Rules: []Rule{
+					{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+						"summary": "{{ value|query }}",
+					}},
+					{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+						"summary": "{{ value|query }}",
+					}},
+				},
+			},
+			expErr: "duplicate",
+		},
+		{
+			group: &Group{Name: "test",
+				Rules: []Rule{
+					{Record: "record", Expr: "up == 1", Labels: map[string]string{
+						"summary": "{{ value|query }}",
+					}},
+					{Record: "record", Expr: "up == 1", Labels: map[string]string{
+						"summary": "{{ value|query }}",
+					}},
+				},
+			},
+			expErr: "duplicate",
+		},
+		{
+			group: &Group{Name: "test",
+				Rules: []Rule{
+					{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+						"summary": "{{ value|query }}",
+					}},
+					{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+						"description": "{{ value|query }}",
+					}},
+				},
+			},
+			expErr: "",
+		},
+		{
+			group: &Group{Name: "test",
+				Rules: []Rule{
+					{Record: "alert", Expr: "up == 1", Labels: map[string]string{
+						"summary": "{{ value|query }}",
+					}},
+					{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+						"summary": "{{ value|query }}",
+					}},
+				},
+			},
+			expErr: "",
+		},
+		{
+			group: &Group{Name: "test thanos",
+				Type: datasource.NewRawType("thanos"),
+				Rules: []Rule{
+					{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+						"description": "{{ value|query }}",
+					}},
+				},
+			},
+			validateExpressions: true,
+			expErr:              "unknown datasource type",
+		},
+		{
+			group: &Group{Name: "test graphite",
+				Type: datasource.NewGraphiteType(),
+				Rules: []Rule{
+					{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+						"description": "some-description",
+					}},
+				},
+			},
+			validateExpressions: true,
+			expErr:              "",
+		},
+		{
+			group: &Group{Name: "test prometheus",
+				Type: datasource.NewPrometheusType(),
+				Rules: []Rule{
+					{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+						"description": "{{ value|query }}",
+					}},
+				},
+			},
+			validateExpressions: true,
+			expErr:              "",
+		},
+		{
+			group: &Group{
+				Name: "test graphite inherit",
+				Type: datasource.NewGraphiteType(),
+				Rules: []Rule{
+					{
+						Expr: "sumSeries(time('foo.bar',10))",
+						For:  utils.NewPromDuration(10 * time.Millisecond),
+					},
+					{
+						Expr: "sum(up == 0 ) by (host)",
+						Type: datasource.NewPrometheusType(),
+					},
+				},
+			},
+		},
+		{
+			group: &Group{
+				Name: "test graphite prometheus bad expr",
+				Type: datasource.NewGraphiteType(),
+				Rules: []Rule{
+					{
+						Expr: "sum(up == 0 ) by (host)",
+						For:  utils.NewPromDuration(10 * time.Millisecond),
+					},
+					{
+						Expr: "sumSeries(time('foo.bar',10))",
+						Type: datasource.NewPrometheusType(),
+					},
+				},
+			},
+			expErr: "invalid rule",
+		},
+	}
+	for _, tc := range testCases {
+		err := tc.group.Validate(tc.validateAnnotations, tc.validateExpressions)
+		if err == nil {
+			if tc.expErr != "" {
+				t.Errorf("expected to get err %q; got nil insted", tc.expErr)
+			}
+			continue
+		}
+		if !strings.Contains(err.Error(), tc.expErr) {
+			t.Errorf("expected err to contain %q; got %q instead", tc.expErr, err)
+		}
+	}
+}
+
+func TestHashRule(t *testing.T) {
+	testCases := []struct {
+		a, b  Rule
+		equal bool
+	}{
+		{
+			Rule{Record: "record", Expr: "up == 1"},
+			Rule{Record: "record", Expr: "up == 1"},
+			true,
+		},
+		{
+			Rule{Alert: "alert", Expr: "up == 1"},
+			Rule{Alert: "alert", Expr: "up == 1"},
+			true,
+		},
+		{
+			Rule{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+				"foo": "bar",
+				"baz": "foo",
+			}},
+			Rule{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+				"foo": "bar",
+				"baz": "foo",
+			}},
+			true,
+		},
+		{
+			Rule{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+				"foo": "bar",
+				"baz": "foo",
+			}},
+			Rule{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+				"baz": "foo",
+				"foo": "bar",
+			}},
+			true,
+		},
+		{
+			Rule{Alert: "record", Expr: "up == 1"},
+			Rule{Alert: "record", Expr: "up == 1"},
+			true,
+		},
+		{
+			Rule{Alert: "alert", Expr: "up == 1", For: utils.NewPromDuration(time.Minute)},
+			Rule{Alert: "alert", Expr: "up == 1"},
+			true,
+		},
+		{
+			Rule{Alert: "record", Expr: "up == 1"},
+			Rule{Record: "record", Expr: "up == 1"},
+			false,
+		},
+		{
+			Rule{Record: "record", Expr: "up == 1"},
+			Rule{Record: "record", Expr: "up == 2"},
+			false,
+		},
+		{
+			Rule{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+				"foo": "bar",
+				"baz": "foo",
+			}},
+			Rule{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+				"baz": "foo",
+				"foo": "baz",
+			}},
+			false,
+		},
+		{
+			Rule{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+				"foo": "bar",
+				"baz": "foo",
+			}},
+			Rule{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+				"baz": "foo",
+			}},
+			false,
+		},
+		{
+			Rule{Alert: "alert", Expr: "up == 1", Labels: map[string]string{
+				"foo": "bar",
+				"baz": "foo",
+			}},
+			Rule{Alert: "alert", Expr: "up == 1"},
+			false,
+		},
+	}
+	for i, tc := range testCases {
+		aID, bID := HashRule(tc.a), HashRule(tc.b)
+		if tc.equal != (aID == bID) {
+			t.Fatalf("missmatch for rule %d", i)
+		}
+	}
+}
+
+func TestGroupChecksum(t *testing.T) {
+	f := func(t *testing.T, data, newData string) {
+		t.Helper()
+		var g Group
+		if err := yaml.Unmarshal([]byte(data), &g); err != nil {
+			t.Fatalf("failed to unmarshal: %s", err)
+		}
+		if g.Checksum == "" {
+			t.Fatalf("expected to get non-empty checksum")
+		}
+
+		var ng Group
+		if err := yaml.Unmarshal([]byte(newData), &ng); err != nil {
+			t.Fatalf("failed to unmarshal: %s", err)
+		}
+		if g.Checksum == ng.Checksum {
+			t.Fatalf("expected to get different checksums")
+		}
+	}
+	t.Run("Ok", func(t *testing.T) {
+		f(t, `
+name: TestGroup
+rules:
+  - alert: ExampleAlertAlwaysFiring
+    expr: sum by(job) (up == 1)
+  - record: handler:requests:rate5m
+    expr: sum(rate(prometheus_http_requests_total[5m])) by (handler)
+`, `
+name: TestGroup
+rules:
+  - record: handler:requests:rate5m
+    expr: sum(rate(prometheus_http_requests_total[5m])) by (handler)
+  - alert: ExampleAlertAlwaysFiring
+    expr: sum by(job) (up == 1)
+`)
+	})
+
+	t.Run("`for` change", func(t *testing.T) {
+		f(t, `
+name: TestGroup
+rules:
+  - alert: ExampleAlertWithFor
+    expr: sum by(job) (up == 1)
+    for: 5m
+`, `
+name: TestGroup
+rules:
+  - alert: ExampleAlertWithFor
+    expr: sum by(job) (up == 1)
+`)
+	})
+	t.Run("`interval` change", func(t *testing.T) {
+		f(t, `
+name: TestGroup
+interval: 2s
+rules:
+  - alert: ExampleAlertWithFor
+    expr: sum by(job) (up == 1)
+`, `
+name: TestGroup
+interval: 4s
+rules:
+  - alert: ExampleAlertWithFor
+    expr: sum by(job) (up == 1)
+`)
+	})
+	t.Run("`concurrency` change", func(t *testing.T) {
+		f(t, `
+name: TestGroup
+concurrency: 2
+rules:
+  - alert: ExampleAlertWithFor
+    expr: sum by(job) (up == 1)
+`, `
+name: TestGroup
+concurrency: 16
+rules:
+  - alert: ExampleAlertWithFor
+    expr: sum by(job) (up == 1)
+`)
+	})
+}

app/vmalert/config/testdata/dir/rules-update0-good.rules

@@ -0,0 +1,15 @@
+groups:
+  - name: TestUpdateGroup
+    interval: 2s
+    concurrency: 2
+    type: prometheus
+    labels:
+      cluster: main
+    rules:
+      - alert: up
+        expr: up == 0
+        for: 30s
+      - alert: up graphite
+        expr: filterSeries(time('host.1',20),'>','0')
+        for: 30s
+        type: graphite

app/vmalert/config/testdata/dir/rules-update1-good.rules

@@ -0,0 +1,12 @@
+groups:
+  - name: TestUpdateGroup
+    interval: 30s
+    type: graphite
+    rules:
+      - alert: up
+        expr: filterSeries(time('host.2',20),'>','0')
+        for: 30s
+      - alert: up graphite
+        expr: filterSeries(time('host.1',20),'>','0')
+        for: 30s
+        type: graphite

app/vmalert/config/testdata/dir/rules0-bad.rules

@@ -0,0 +1,19 @@
+groups:
+  - name: group
+    rules:
+      - alert: InvalidAnnotations
+        for: 5m
+        expr: vm_rows > 0
+        labels:
+          label: bar
+        annotations:
+          summary: "{{ $value }"
+          description: "{{$labels}}"
+      - alert: UnkownAnnotationsFunction
+        for: 5m
+        expr: vm_rows > 0
+        labels:
+          label: bar
+        annotations:
+          summary: "{{ value|query }}"
+          description: "{{$labels}}"

app/vmalert/config/testdata/dir/rules0-good.rules

@@ -0,0 +1,14 @@
+groups:
+  - name: duplicatedGroupDiffFiles
+    rules:
+      - alert: VMRows
+        for: 5m
+        expr: vm_rows > 0
+        labels:
+          label: bar
+          expr: "{{ $expr|queryEscape }}"
+        annotations:
+          summary: "{{ $value|humanize }}"
+          description: "{{$labels}}"
+
+

app/vmalert/config/testdata/dir/rules1-bad.rules

@@ -0,0 +1,22 @@
+groups:
+  - name: sameGroup
+    rules:
+      - alert: alert
+        for: 5m
+        expr: vm_rows > 0
+        labels:
+          label: bar
+        annotations:
+          summary: "{{ $value }}"
+          description: "{{$labels}}"
+  - name: sameGroup
+    rules:
+      - alert: alert
+        for: 5m
+        expr: vm_rows > 0
+        labels:
+          label: bar
+        annotations:
+          summary: "{{ $value }}"
+          description: "{{$labels}}"
+

app/vmalert/config/testdata/dir/rules1-good.rules

@@ -0,0 +1,13 @@
+groups:
+  - name: duplicatedGroupDiffFiles
+    labels:
+       dc: gcp
+    rules:
+      - alert: VMRows
+        for: 5m
+        expr: vm_rows > 0
+        labels:
+          label: bar
+        annotations:
+          summary: "{{ $value }}"
+          description: "{{$labels}}"

app/vmalert/config/testdata/dir/rules2-bad.rules

@@ -0,0 +1,11 @@
+groups:
+  - name: group
+    rules:
+      - alert: UnkownLabelFunction
+        for: 5m
+        expr: vm_rows > 0
+        labels:
+          label: bar
+          summary: "{{ unknown|query }}"
+        annotations:
+          description: "{{$labels}}"

app/vmalert/config/testdata/dir/rules3-bad.rules

@@ -0,0 +1,5 @@
+groups:
+  - name: group
+    rules:
+      - for: 5m
+        expr: vm_rows > 0

app/vmalert/config/testdata/dir/rules4-bad.rules

@@ -0,0 +1,7 @@
+groups:
+  - name: group
+    rules:
+      - alert: rows
+        record: record
+        for: 5m
+        expr: vm_rows > 0

app/vmalert/config/testdata/dir/rules5-bad.rules

@@ -0,0 +1,7 @@
+groups:
+  - name: group
+    rules:
+      - alert: rows
+        expr: vm_rows > 0
+      - record: rows
+        expr: sum(vm_rows)

app/vmalert/config/testdata/rules-query-good.rules

@@ -0,0 +1,15 @@
+groups:
+  - name: alertmanager.rules
+    rules:
+      - alert: AlertmanagerConfigInconsistent
+        annotations:
+          message: |
+            The configuration of the instances of the Alertmanager cluster `{{ $labels.namespace }}/{{ $labels.service }}` are out of sync.
+            {{ range printf "alertmanager_config_hash{namespace=\"%s\",service=\"%s\"}" $labels.namespace $labels.service | query }}
+            Configuration hash for pod {{ .Labels.pod }} is "{{ printf "%.f" .Value }}"
+            {{ end }}
+        expr: |
+          count by(namespace,service) (count_values by(namespace,service) ("config_hash", alertmanager_config_hash{job="alertmanager-main",namespace="openshift-monitoring"})) != 1
+        for: 5m
+        labels:
+          severity: critical

app/vmalert/config/testdata/rules-replay-good.rules

@@ -0,0 +1,39 @@
+groups:
+  - name: ReplayGroup
+    interval: 1m
+    concurrency: 1
+    rules:
+      - record: type:vm_cache_entries:rate5m
+        expr: sum(rate(vm_cache_entries[5m])) by (type)
+        labels:
+          recording: true
+      - record: go_cgo_calls_count:rate5m
+        expr: rate(go_cgo_calls_count{job="vmdb"}[5m])
+        labels:
+          recording: true
+
+  - name: vmsingleReplay
+    interval: 30s
+    concurrency: 2
+    rules:
+      - alert: RequestErrorsToAPI
+        expr: increase(vm_http_request_errors_total[5m]) > 0
+        for: 15m
+        labels:
+          severity: warning
+        annotations:
+          dashboard: "http://localhost:3000/d/wNf0q_kZk?viewPanel=35&var-instance={{ $labels.instance }}"
+          summary: "Too many errors served for path {{ $labels.path }} (instance {{ $labels.instance }})"
+          description: "Requests to path {{ $labels.path }} are receiving errors.
+            Please verify if clients are sending correct requests."
+
+      - alert: TooManyLogs
+        expr: sum(increase(vm_log_messages_total{level!="info"}[5m])) by (job, instance) > 0
+        for: 15m
+        labels:
+          severity: warning
+        annotations:
+          dashboard: "http://localhost:3000/d/wNf0q_kZk?viewPanel=67&var-instance={{ $labels.instance }}"
+          summary: "Too many logs printed for job \"{{ $labels.job }}\" ({{ $labels.instance }})"
+          description: "Logging rate for job \"{{ $labels.job }}\" ({{ $labels.instance }}) is {{ $value }} for last 15m.\n
+           Worth to check logs for specific error messages."

app/vmalert/config/testdata/rules0-bad.rules

@@ -0,0 +1,28 @@
+groups:
+  - name: group
+    rules:
+      - alert: InvalidExpr
+        for: 5m
+        expr: vm_rows{ > 0
+        labels:
+          label: bar
+        annotations:
+          summary: "{{ $value }}"
+          description: "{{$labels}}"
+      - alert: EmptyExpr
+        for: 5m
+        expr: ""
+        labels:
+          label: bar
+        annotations:
+          summary: "{{ $value }}"
+          description: "{{$labels}}"
+      - alert: ""
+        for: 5m
+        expr: vm_rows > 0
+        labels:
+          label: foo
+        annotations:
+          summary: "{{ $value }}"
+          description: "{{$labels}}"
+

app/vmalert/config/testdata/rules0-good.rules

@@ -0,0 +1,23 @@
+groups:
+  - name: groupGorSingleAlert
+    rules:
+      - alert: VMRows
+        for: 10s
+        expr: vm_rows > 0
+        labels:
+          label: bar
+          host: "{{ $labels.instance }}"
+        annotations:
+          summary: "{{ $value|humanize }}"
+          description: "{{$labels}}"
+
+  - name: TestGroup
+    rules:
+      - alert: Conns
+        expr: sum(vm_tcplistener_conns) by(instance) > 1
+        annotations:
+          summary: "Too high connection number for {{$labels.instance}}"
+          description: "It is {{ $value }} connections for {{$labels.instance}}"
+      - alert: ExampleAlertAlwaysFiring
+        expr: sum by(job)
+          (up == 1)

app/vmalert/config/testdata/rules1-bad.rules

@@ -0,0 +1,12 @@
+groups:
+  - name: TestGraphiteBadGroup
+    interval: 2s
+    concurrency: 2
+    type: graphite
+    rules:
+      - alert: Conns
+        expr: filterSeries(sumSeries(host.receiver.interface.cons),'last','>', 500) by instance
+        for: 3m
+        annotations:
+          summary: Too high connection number for {{$labels.instance}}
+          description: "It is {{ $value }} connections for {{$labels.instance}}"

app/vmalert/config/testdata/rules1-good.rules

@@ -0,0 +1,11 @@
+groups:
+  - name: groupTest
+    rules:
+      - alert: VMRows
+        for: 1ms
+        expr: vm_rows > 0
+        labels:
+          label: bar
+          host: "{{ $labels.instance }}"
+        annotations:
+          summary: "{{ $value }}"

app/vmalert/config/testdata/rules2-good.rules

@@ -0,0 +1,48 @@
+groups:
+  - name: TestGroup
+    interval: 2s
+    concurrency: 2
+    extra_filter_labels:
+        job: victoriametrics
+    rules:
+      - alert: Conns
+        expr: sum(vm_tcplistener_conns) by(instance) > 1
+        for: 3m
+        annotations:
+          summary: Too high connection number for {{$labels.instance}}
+            {{ with printf "sum(vm_tcplistener_conns{instance=%q})" .Labels.instance | query }}
+              {{ . | first | value }}
+            {{ end }}
+          description: "It is {{ $value }} connections for {{$labels.instance}}"
+      - alert: ExampleAlertAlwaysFiring
+        expr: sum by(job)
+          (up == 1)
+        labels:
+          job: '{{ $labels.job }}'
+          dynamic: '{{ $x := query "up" | first | value }}{{ if eq 1.0 $x }}one{{ else }}unknown{{ end }}'
+        annotations:
+          description: Job {{ $labels.job }} is up!
+          summary: All instances up {{ range query "up" }}
+            {{ . | label "instance" }}
+            {{ end }}
+      - record: handler:requests:rate5m
+        expr: sum(rate(prometheus_http_requests_total[5m])) by (handler)
+        labels:
+          recording: true
+      - record: code:requests:rate5m
+        expr: sum(rate(promhttp_metric_handler_requests_total[5m])) by (code)
+        labels:
+          env: dev
+          recording: true
+      - record: code:requests:rate5m
+        expr: sum(rate(promhttp_metric_handler_requests_total[5m])) by (code)
+        labels:
+          env: staging
+          recording: true
+      - record: successful_requests:ratio_rate5m
+        labels:
+          recording: true
+        expr: |2
+            sum(code:requests:rate5m{code="200"})
+          /
+            sum(code:requests:rate5m)

app/vmalert/config/testdata/rules3-good.rules

@@ -0,0 +1,30 @@
+groups:
+  - name: TestGroup
+    interval: 2s
+    concurrency: 2
+    type: graphite
+    rules:
+      - alert: Conns
+        expr: filterSeries(sumSeries(host.receiver.interface.cons),'last','>', 500)
+        for: 3m
+        annotations:
+          summary: Too high connection number for {{$labels.instance}}
+          description: "It is {{ $value }} connections for {{$labels.instance}}"
+  - name: TestGroupPromMixed
+    interval: 2s
+    concurrency: 2
+    type: prometheus
+    rules:
+      - alert: Conns
+        expr: sum(vm_tcplistener_conns) by (instance) > 1
+        for: 3m
+        annotations:
+          summary: Too high connection number for {{$labels.instance}}
+          description: "It is {{ $value }} connections for {{$labels.instance}}"
+      - alert: HostDown
+        type: graphite
+        expr: filterSeries(sumSeries(host.receiver.interface.up),'last','=', 0)
+        for: 3m
+        annotations:
+          summary: Too high connection number for {{$labels.instance}}
+          description: "It is {{ $value }} connections for {{$labels.instance}}"

app/vmalert/datasource/datasource.go

@@ -0,0 +1,66 @@
+package datasource
+
+import (
+	"context"
+	"time"
+)
+
+// Querier interface wraps Query and QueryRange methods
+type Querier interface {
+	Query(ctx context.Context, query string) ([]Metric, error)
+	QueryRange(ctx context.Context, query string, from, to time.Time) ([]Metric, error)
+}
+
+// QuerierBuilder builds Querier with given params.
+type QuerierBuilder interface {
+	BuildWithParams(params QuerierParams) Querier
+}
+
+// QuerierParams params for Querier.
+type QuerierParams struct {
+	DataSourceType     *Type
+	EvaluationInterval time.Duration
+	// see https://docs.victoriametrics.com/#prometheus-querying-api-enhancements
+	ExtraLabels map[string]string
+}
+
+// Metric is the basic entity which should be return by datasource
+type Metric struct {
+	Labels     []Label
+	Timestamps []int64
+	Values     []float64
+}
+
+// SetLabel adds or updates existing one label
+// by the given key and label
+func (m *Metric) SetLabel(key, value string) {
+	for i, l := range m.Labels {
+		if l.Name == key {
+			m.Labels[i].Value = value
+			return
+		}
+	}
+	m.AddLabel(key, value)
+}
+
+// AddLabel appends the given label to the label set
+func (m *Metric) AddLabel(key, value string) {
+	m.Labels = append(m.Labels, Label{Name: key, Value: value})
+}
+
+// Label returns the given label value.
+// If label is missing empty string will be returned
+func (m *Metric) Label(key string) string {
+	for _, l := range m.Labels {
+		if l.Name == key {
+			return l.Value
+		}
+	}
+	return ""
+}
+
+// Label represents metric's label
+type Label struct {
+	Name  string
+	Value string
+}

app/vmalert/datasource/datasource_test.go

@@ -0,0 +1,18 @@
+package datasource
+
+import "testing"
+
+func TestMetric_Label(t *testing.T) {
+	m := &Metric{}
+
+	m.AddLabel("foo", "bar")
+	checkEqualString(t, "bar", m.Label("foo"))
+
+	m.SetLabel("foo", "baz")
+	checkEqualString(t, "baz", m.Label("foo"))
+
+	m.SetLabel("qux", "quux")
+	checkEqualString(t, "quux", m.Label("qux"))
+
+	checkEqualString(t, "", m.Label("non-existing"))
+}

app/vmalert/datasource/init.go

@@ -0,0 +1,78 @@
+package datasource
+
+import (
+	"flag"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+)
+
+var (
+	addr = flag.String("datasource.url", "", "VictoriaMetrics or vmselect url. Required parameter. "+
+		"E.g. http://127.0.0.1:8428")
+	appendTypePrefix      = flag.Bool("datasource.appendTypePrefix", false, "Whether to add type prefix to -datasource.url based on the query type. Set to true if sending different query types to the vmselect URL.")
+	basicAuthUsername     = flag.String("datasource.basicAuth.username", "", "Optional basic auth username for -datasource.url")
+	basicAuthPassword     = flag.String("datasource.basicAuth.password", "", "Optional basic auth password for -datasource.url")
+	basicAuthPasswordFile = flag.String("datasource.basicAuth.passwordFile", "", "Optional path to basic auth password to use for -datasource.url")
+	bearerToken           = flag.String("datasource.bearerToken", "", "Optional bearer auth token to use for -datasource.url.")
+	bearerTokenFile       = flag.String("datasource.bearerTokenFile", "", "Optional path to bearer token file to use for -datasource.url.")
+
+	tlsInsecureSkipVerify = flag.Bool("datasource.tlsInsecureSkipVerify", false, "Whether to skip tls verification when connecting to -datasource.url")
+	tlsCertFile           = flag.String("datasource.tlsCertFile", "", "Optional path to client-side TLS certificate file to use when connecting to -datasource.url")
+	tlsKeyFile            = flag.String("datasource.tlsKeyFile", "", "Optional path to client-side TLS certificate key to use when connecting to -datasource.url")
+	tlsCAFile             = flag.String("datasource.tlsCAFile", "", `Optional path to TLS CA file to use for verifying connections to -datasource.url. By default, system CA is used`)
+	tlsServerName         = flag.String("datasource.tlsServerName", "", `Optional TLS server name to use for connections to -datasource.url. By default, the server name from -datasource.url is used`)
+
+	lookBack  = flag.Duration("datasource.lookback", 0, `Lookback defines how far into the past to look when evaluating queries. For example, if the datasource.lookback=5m then param "time" with value now()-5m will be added to every query.`)
+	queryStep = flag.Duration("datasource.queryStep", 0, "queryStep defines how far a value can fallback to when evaluating queries. "+
+		"For example, if datasource.queryStep=15s then param \"step\" with value \"15s\" will be added to every query."+
+		"If queryStep isn't specified, rule's evaluationInterval will be used instead.")
+	maxIdleConnections = flag.Int("datasource.maxIdleConnections", 100, `Defines the number of idle (keep-alive connections) to each configured datasource. Consider setting this value equal to the value: groups_total * group.concurrency. Too low a value may result in a high number of sockets in TIME_WAIT state.`)
+	roundDigits        = flag.Int("datasource.roundDigits", 0, `Adds "round_digits" GET param to datasource requests. `+
+		`In VM "round_digits" limits the number of digits after the decimal point in response values.`)
+)
+
+// Param represents an HTTP GET param
+type Param struct {
+	Key, Value string
+}
+
+// Init creates a Querier from provided flag values.
+// Provided extraParams will be added as GET params to
+// each request.
+func Init(extraParams []Param) (QuerierBuilder, error) {
+	if *addr == "" {
+		return nil, fmt.Errorf("datasource.url is empty")
+	}
+
+	tr, err := utils.Transport(*addr, *tlsCertFile, *tlsKeyFile, *tlsCAFile, *tlsServerName, *tlsInsecureSkipVerify)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create transport: %w", err)
+	}
+	tr.MaxIdleConnsPerHost = *maxIdleConnections
+
+	if *roundDigits > 0 {
+		extraParams = append(extraParams, Param{
+			Key:   "round_digits",
+			Value: fmt.Sprintf("%d", *roundDigits),
+		})
+	}
+
+	authCfg, err := utils.AuthConfig(*basicAuthUsername, *basicAuthPassword, *basicAuthPasswordFile, *bearerToken, *bearerTokenFile)
+	if err != nil {
+		return nil, fmt.Errorf("failed to configure auth: %w", err)
+	}
+
+	return &VMStorage{
+		c:                &http.Client{Transport: tr},
+		authCfg:          authCfg,
+		datasourceURL:    strings.TrimSuffix(*addr, "/"),
+		appendTypePrefix: *appendTypePrefix,
+		lookBack:         *lookBack,
+		queryStep:        *queryStep,
+		dataSourceType:   NewPrometheusType(),
+		extraParams:      extraParams,
+	}, nil
+}

app/vmalert/datasource/type.go

@@ -0,0 +1,89 @@
+package datasource
+
+import (
+	"fmt"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmselect/graphiteql"
+	"github.com/VictoriaMetrics/metricsql"
+)
+
+const graphiteType = "graphite"
+const prometheusType = "prometheus"
+
+// Type represents data source type
+type Type struct {
+	name string
+}
+
+// NewPrometheusType returns prometheus datasource type
+func NewPrometheusType() Type {
+	return Type{name: prometheusType}
+}
+
+// NewGraphiteType returns graphite datasource type
+func NewGraphiteType() Type {
+	return Type{name: graphiteType}
+}
+
+// NewRawType returns datasource type from raw string
+// without validation.
+func NewRawType(d string) Type {
+	return Type{name: d}
+}
+
+// Get returns datasource type
+func (t *Type) Get() string {
+	return t.name
+}
+
+// Set changes datasource type
+func (t *Type) Set(d Type) {
+	t.name = d.name
+}
+
+// String implements String interface with default value.
+func (t Type) String() string {
+	if t.name == "" {
+		return prometheusType
+	}
+	return t.name
+}
+
+// ValidateExpr validates query expression with datasource ql.
+func (t *Type) ValidateExpr(expr string) error {
+	switch t.name {
+	case graphiteType:
+		if _, err := graphiteql.Parse(expr); err != nil {
+			return fmt.Errorf("bad graphite expr: %q, err: %w", expr, err)
+		}
+	case "", prometheusType:
+		if _, err := metricsql.Parse(expr); err != nil {
+			return fmt.Errorf("bad prometheus expr: %q, err: %w", expr, err)
+		}
+	default:
+		return fmt.Errorf("unknown datasource type=%q", t.name)
+	}
+	return nil
+}
+
+// UnmarshalYAML implements the yaml.Unmarshaler interface.
+func (t *Type) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var s string
+	if err := unmarshal(&s); err != nil {
+		return err
+	}
+	switch s {
+	case "":
+		s = prometheusType
+	case graphiteType, prometheusType:
+	default:
+		return fmt.Errorf("unknown datasource type=%q, want %q or %q", s, prometheusType, graphiteType)
+	}
+	t.name = s
+	return nil
+}
+
+// MarshalYAML implements the yaml.Unmarshaler interface.
+func (t Type) MarshalYAML() (interface{}, error) {
+	return t.name, nil
+}

app/vmalert/datasource/vm.go

@@ -0,0 +1,157 @@
+package datasource
+
+import (
+	"context"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promauth"
+)
+
+// VMStorage represents vmstorage entity with ability to read and write metrics
+type VMStorage struct {
+	c                *http.Client
+	authCfg          *promauth.Config
+	datasourceURL    string
+	appendTypePrefix bool
+	lookBack         time.Duration
+	queryStep        time.Duration
+
+	dataSourceType     Type
+	evaluationInterval time.Duration
+	extraLabels        []string
+	extraParams        []Param
+}
+
+// Clone makes clone of VMStorage, shares http client.
+func (s *VMStorage) Clone() *VMStorage {
+	return &VMStorage{
+		c:                s.c,
+		authCfg:          s.authCfg,
+		datasourceURL:    s.datasourceURL,
+		lookBack:         s.lookBack,
+		queryStep:        s.queryStep,
+		appendTypePrefix: s.appendTypePrefix,
+		dataSourceType:   s.dataSourceType,
+	}
+}
+
+// ApplyParams - changes given querier params.
+func (s *VMStorage) ApplyParams(params QuerierParams) *VMStorage {
+	if params.DataSourceType != nil {
+		s.dataSourceType = *params.DataSourceType
+	}
+	s.evaluationInterval = params.EvaluationInterval
+	for k, v := range params.ExtraLabels {
+		s.extraLabels = append(s.extraLabels, fmt.Sprintf("%s=%s", k, v))
+	}
+	return s
+}
+
+// BuildWithParams - implements interface.
+func (s *VMStorage) BuildWithParams(params QuerierParams) Querier {
+	return s.Clone().ApplyParams(params)
+}
+
+// NewVMStorage is a constructor for VMStorage
+func NewVMStorage(baseURL string, authCfg *promauth.Config, lookBack time.Duration, queryStep time.Duration, appendTypePrefix bool, c *http.Client) *VMStorage {
+	return &VMStorage{
+		c:                c,
+		authCfg:          authCfg,
+		datasourceURL:    strings.TrimSuffix(baseURL, "/"),
+		appendTypePrefix: appendTypePrefix,
+		lookBack:         lookBack,
+		queryStep:        queryStep,
+		dataSourceType:   NewPrometheusType(),
+	}
+}
+
+// Query executes the given query and returns parsed response
+func (s *VMStorage) Query(ctx context.Context, query string) ([]Metric, error) {
+	req, err := s.newRequestPOST()
+	if err != nil {
+		return nil, err
+	}
+
+	ts := time.Now()
+	switch s.dataSourceType.name {
+	case "", prometheusType:
+		s.setPrometheusInstantReqParams(req, query, ts)
+	case graphiteType:
+		s.setGraphiteReqParams(req, query, ts)
+	default:
+		return nil, fmt.Errorf("engine not found: %q", s.dataSourceType.name)
+	}
+
+	resp, err := s.do(ctx, req)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		_ = resp.Body.Close()
+	}()
+
+	parseFn := parsePrometheusResponse
+	if s.dataSourceType.name != prometheusType {
+		parseFn = parseGraphiteResponse
+	}
+	return parseFn(req, resp)
+}
+
+// QueryRange executes the given query on the given time range.
+// For Prometheus type see https://prometheus.io/docs/prometheus/latest/querying/api/#range-queries
+// Graphite type isn't supported.
+func (s *VMStorage) QueryRange(ctx context.Context, query string, start, end time.Time) ([]Metric, error) {
+	if s.dataSourceType.name != prometheusType {
+		return nil, fmt.Errorf("%q is not supported for QueryRange", s.dataSourceType.name)
+	}
+	req, err := s.newRequestPOST()
+	if err != nil {
+		return nil, err
+	}
+	if start.IsZero() {
+		return nil, fmt.Errorf("start param is missing")
+	}
+	if end.IsZero() {
+		return nil, fmt.Errorf("end param is missing")
+	}
+	s.setPrometheusRangeReqParams(req, query, start, end)
+	resp, err := s.do(ctx, req)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		_ = resp.Body.Close()
+	}()
+	return parsePrometheusResponse(req, resp)
+}
+
+func (s *VMStorage) do(ctx context.Context, req *http.Request) (*http.Response, error) {
+	resp, err := s.c.Do(req.WithContext(ctx))
+	if err != nil {
+		return nil, fmt.Errorf("error getting response from %s: %w", req.URL, err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		body, _ := ioutil.ReadAll(resp.Body)
+		_ = resp.Body.Close()
+		return nil, fmt.Errorf("unexpected response code %d for %s. Response body %s", resp.StatusCode, req.URL, body)
+	}
+	return resp, nil
+}
+
+func (s *VMStorage) newRequestPOST() (*http.Request, error) {
+	req, err := http.NewRequest("POST", s.datasourceURL, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/json; charset=utf-8")
+	if s.authCfg != nil {
+		if auth := s.authCfg.GetAuthHeader(); auth != "" {
+			req.Header.Set("Authorization", auth)
+		}
+	}
+	return req, nil
+}

app/vmalert/datasource/vm_graphite_api.go

@@ -0,0 +1,67 @@
+package datasource
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+	"time"
+)
+
+type graphiteResponse []graphiteResponseTarget
+
+type graphiteResponseTarget struct {
+	Target     string            `json:"target"`
+	Tags       map[string]string `json:"tags"`
+	DataPoints [][2]float64      `json:"datapoints"`
+}
+
+func (r graphiteResponse) metrics() []Metric {
+	var ms []Metric
+	for _, res := range r {
+		if len(res.DataPoints) < 1 {
+			continue
+		}
+		var m Metric
+		// add only last value to the result.
+		last := res.DataPoints[len(res.DataPoints)-1]
+		m.Values = append(m.Values, last[0])
+		m.Timestamps = append(m.Timestamps, int64(last[1]))
+		for k, v := range res.Tags {
+			m.AddLabel(k, v)
+		}
+		ms = append(ms, m)
+	}
+	return ms
+}
+
+func parseGraphiteResponse(req *http.Request, resp *http.Response) ([]Metric, error) {
+	r := &graphiteResponse{}
+	if err := json.NewDecoder(resp.Body).Decode(r); err != nil {
+		return nil, fmt.Errorf("error parsing graphite metrics for %s: %w", req.URL, err)
+	}
+	return r.metrics(), nil
+}
+
+const (
+	graphitePath   = "/render"
+	graphitePrefix = "/graphite"
+)
+
+func (s *VMStorage) setGraphiteReqParams(r *http.Request, query string, timestamp time.Time) {
+	if s.appendTypePrefix {
+		r.URL.Path += graphitePrefix
+	}
+	r.URL.Path += graphitePath
+	q := r.URL.Query()
+	q.Set("format", "json")
+	q.Set("target", query)
+	from := "-5min"
+	if s.lookBack > 0 {
+		lookBack := timestamp.Add(-s.lookBack)
+		from = strconv.FormatInt(lookBack.Unix(), 10)
+	}
+	q.Set("from", from)
+	q.Set("until", "now")
+	r.URL.RawQuery = q.Encode()
+}

app/vmalert/datasource/vm_prom_api.go

@@ -0,0 +1,165 @@
+package datasource
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+	"time"
+)
+
+type promResponse struct {
+	Status    string `json:"status"`
+	ErrorType string `json:"errorType"`
+	Error     string `json:"error"`
+	Data      struct {
+		ResultType string          `json:"resultType"`
+		Result     json.RawMessage `json:"result"`
+	} `json:"data"`
+}
+
+type promInstant struct {
+	Result []struct {
+		Labels map[string]string `json:"metric"`
+		TV     [2]interface{}    `json:"value"`
+	} `json:"result"`
+}
+
+type promRange struct {
+	Result []struct {
+		Labels map[string]string `json:"metric"`
+		TVs    [][2]interface{}  `json:"values"`
+	} `json:"result"`
+}
+
+func (r promInstant) metrics() ([]Metric, error) {
+	var result []Metric
+	for i, res := range r.Result {
+		f, err := strconv.ParseFloat(res.TV[1].(string), 64)
+		if err != nil {
+			return nil, fmt.Errorf("metric %v, unable to parse float64 from %s: %w", res, res.TV[1], err)
+		}
+		var m Metric
+		for k, v := range r.Result[i].Labels {
+			m.AddLabel(k, v)
+		}
+		m.Timestamps = append(m.Timestamps, int64(res.TV[0].(float64)))
+		m.Values = append(m.Values, f)
+		result = append(result, m)
+	}
+	return result, nil
+}
+
+func (r promRange) metrics() ([]Metric, error) {
+	var result []Metric
+	for i, res := range r.Result {
+		var m Metric
+		for _, tv := range res.TVs {
+			f, err := strconv.ParseFloat(tv[1].(string), 64)
+			if err != nil {
+				return nil, fmt.Errorf("metric %v, unable to parse float64 from %s: %w", res, tv[1], err)
+			}
+			m.Values = append(m.Values, f)
+			m.Timestamps = append(m.Timestamps, int64(tv[0].(float64)))
+		}
+		if len(m.Values) < 1 || len(m.Timestamps) < 1 {
+			return nil, fmt.Errorf("metric %v contains no values", res)
+		}
+		m.Labels = nil
+		for k, v := range r.Result[i].Labels {
+			m.AddLabel(k, v)
+		}
+		result = append(result, m)
+	}
+	return result, nil
+}
+
+const (
+	statusSuccess, statusError = "success", "error"
+	rtVector, rtMatrix         = "vector", "matrix"
+)
+
+func parsePrometheusResponse(req *http.Request, resp *http.Response) ([]Metric, error) {
+	r := &promResponse{}
+	if err := json.NewDecoder(resp.Body).Decode(r); err != nil {
+		return nil, fmt.Errorf("error parsing prometheus metrics for %s: %w", req.URL, err)
+	}
+	if r.Status == statusError {
+		return nil, fmt.Errorf("response error, query: %s, errorType: %s, error: %s", req.URL, r.ErrorType, r.Error)
+	}
+	if r.Status != statusSuccess {
+		return nil, fmt.Errorf("unknown status: %s, Expected success or error ", r.Status)
+	}
+	switch r.Data.ResultType {
+	case rtVector:
+		var pi promInstant
+		if err := json.Unmarshal(r.Data.Result, &pi.Result); err != nil {
+			return nil, fmt.Errorf("umarshal err %s; \n %#v", err, string(r.Data.Result))
+		}
+		return pi.metrics()
+	case rtMatrix:
+		var pr promRange
+		if err := json.Unmarshal(r.Data.Result, &pr.Result); err != nil {
+			return nil, err
+		}
+		return pr.metrics()
+	default:
+		return nil, fmt.Errorf("unknown result type %q", r.Data.ResultType)
+	}
+}
+
+const (
+	prometheusInstantPath = "/api/v1/query"
+	prometheusRangePath   = "/api/v1/query_range"
+	prometheusPrefix      = "/prometheus"
+)
+
+func (s *VMStorage) setPrometheusInstantReqParams(r *http.Request, query string, timestamp time.Time) {
+	if s.appendTypePrefix {
+		r.URL.Path += prometheusPrefix
+	}
+	r.URL.Path += prometheusInstantPath
+	q := r.URL.Query()
+	if s.lookBack > 0 {
+		timestamp = timestamp.Add(-s.lookBack)
+	}
+	if s.evaluationInterval > 0 {
+		// see https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1232
+		timestamp = timestamp.Truncate(s.evaluationInterval)
+	}
+	q.Set("time", fmt.Sprintf("%d", timestamp.Unix()))
+	r.URL.RawQuery = q.Encode()
+	s.setPrometheusReqParams(r, query)
+}
+
+func (s *VMStorage) setPrometheusRangeReqParams(r *http.Request, query string, start, end time.Time) {
+	if s.appendTypePrefix {
+		r.URL.Path += prometheusPrefix
+	}
+	r.URL.Path += prometheusRangePath
+	q := r.URL.Query()
+	q.Add("start", fmt.Sprintf("%d", start.Unix()))
+	q.Add("end", fmt.Sprintf("%d", end.Unix()))
+	r.URL.RawQuery = q.Encode()
+	s.setPrometheusReqParams(r, query)
+}
+
+func (s *VMStorage) setPrometheusReqParams(r *http.Request, query string) {
+	q := r.URL.Query()
+	q.Set("query", query)
+	if s.evaluationInterval > 0 {
+		// set step as evaluationInterval by default
+		q.Set("step", s.evaluationInterval.String())
+	}
+	if s.queryStep > 0 {
+		// override step with user-specified value
+		q.Set("step", s.queryStep.String())
+	}
+	for _, l := range s.extraLabels {
+		q.Add("extra_label", l)
+	}
+	for _, p := range s.extraParams {
+		q.Add(p.Key, p.Value)
+	}
+	r.URL.RawQuery = q.Encode()
+}

app/vmalert/datasource/vm_test.go

@@ -0,0 +1,488 @@
+package datasource
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"reflect"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promauth"
+)
+
+var (
+	ctx           = context.Background()
+	basicAuthName = "foo"
+	basicAuthPass = "bar"
+	baCfg         = &promauth.BasicAuthConfig{
+		Username: basicAuthName,
+		Password: basicAuthPass,
+	}
+	query       = "vm_rows"
+	queryRender = "constantLine(10)"
+)
+
+func TestVMInstantQuery(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/", func(_ http.ResponseWriter, _ *http.Request) {
+		t.Errorf("should not be called")
+	})
+	c := -1
+	mux.HandleFunc("/render", func(w http.ResponseWriter, request *http.Request) {
+		c++
+		switch c {
+		case 7:
+			w.Write([]byte(`[{"target":"constantLine(10)","tags":{"name":"constantLine(10)"},"datapoints":[[10,1611758343],[10,1611758373],[10,1611758403]]}]`))
+		}
+	})
+	mux.HandleFunc("/api/v1/query", func(w http.ResponseWriter, r *http.Request) {
+		c++
+		if r.Method != http.MethodPost {
+			t.Errorf("expected POST method got %s", r.Method)
+		}
+		if name, pass, _ := r.BasicAuth(); name != basicAuthName || pass != basicAuthPass {
+			t.Errorf("expected %s:%s as basic auth got %s:%s", basicAuthName, basicAuthPass, name, pass)
+		}
+		if r.URL.Query().Get("query") != query {
+			t.Errorf("expected %s in query param, got %s", query, r.URL.Query().Get("query"))
+		}
+		timeParam := r.URL.Query().Get("time")
+		if timeParam == "" {
+			t.Errorf("expected 'time' in query param, got nil instead")
+		}
+		if _, err := strconv.ParseInt(timeParam, 10, 64); err != nil {
+			t.Errorf("failed to parse 'time' query param: %s", err)
+		}
+		switch c {
+		case 0:
+			conn, _, _ := w.(http.Hijacker).Hijack()
+			_ = conn.Close()
+		case 1:
+			w.WriteHeader(500)
+		case 2:
+			w.Write([]byte("[]"))
+		case 3:
+			w.Write([]byte(`{"status":"error", "errorType":"type:", "error":"some error msg"}`))
+		case 4:
+			w.Write([]byte(`{"status":"unknown"}`))
+		case 5:
+			w.Write([]byte(`{"status":"success","data":{"resultType":"matrix"}}`))
+		case 6:
+			w.Write([]byte(`{"status":"success","data":{"resultType":"vector","result":[{"metric":{"__name__":"vm_rows"},"value":[1583786142,"13763"]},{"metric":{"__name__":"vm_requests"},"value":[1583786140,"2000"]}]}}`))
+		}
+	})
+
+	srv := httptest.NewServer(mux)
+	defer srv.Close()
+
+	authCfg, err := promauth.NewConfig(".", nil, baCfg, "", "", nil, nil)
+	if err != nil {
+		t.Fatalf("unexpected: %s", err)
+	}
+	s := NewVMStorage(srv.URL, authCfg, time.Minute, 0, false, srv.Client())
+
+	p := NewPrometheusType()
+	pq := s.BuildWithParams(QuerierParams{DataSourceType: &p, EvaluationInterval: 15 * time.Second})
+
+	if _, err := pq.Query(ctx, query); err == nil {
+		t.Fatalf("expected connection error got nil")
+	}
+	if _, err := pq.Query(ctx, query); err == nil {
+		t.Fatalf("expected invalid response status error got nil")
+	}
+	if _, err := pq.Query(ctx, query); err == nil {
+		t.Fatalf("expected response body error got nil")
+	}
+	if _, err := pq.Query(ctx, query); err == nil {
+		t.Fatalf("expected error status got nil")
+	}
+	if _, err := pq.Query(ctx, query); err == nil {
+		t.Fatalf("expected unknown status got nil")
+	}
+	if _, err := pq.Query(ctx, query); err == nil {
+		t.Fatalf("expected non-vector resultType error  got nil")
+	}
+	m, err := pq.Query(ctx, query)
+	if err != nil {
+		t.Fatalf("unexpected %s", err)
+	}
+	if len(m) != 2 {
+		t.Fatalf("expected 2 metrics got %d in %+v", len(m), m)
+	}
+	expected := []Metric{
+		{
+			Labels:     []Label{{Value: "vm_rows", Name: "__name__"}},
+			Timestamps: []int64{1583786142},
+			Values:     []float64{13763},
+		},
+		{
+			Labels:     []Label{{Value: "vm_requests", Name: "__name__"}},
+			Timestamps: []int64{1583786140},
+			Values:     []float64{2000},
+		},
+	}
+	if !reflect.DeepEqual(m, expected) {
+		t.Fatalf("unexpected metric %+v want %+v", m, expected)
+	}
+
+	g := NewGraphiteType()
+	gq := s.BuildWithParams(QuerierParams{DataSourceType: &g})
+
+	m, err = gq.Query(ctx, queryRender)
+	if err != nil {
+		t.Fatalf("unexpected %s", err)
+	}
+	if len(m) != 1 {
+		t.Fatalf("expected 1 metric  got %d in %+v", len(m), m)
+	}
+	exp := Metric{
+		Labels:     []Label{{Value: "constantLine(10)", Name: "name"}},
+		Timestamps: []int64{1611758403},
+		Values:     []float64{10},
+	}
+	if !reflect.DeepEqual(m[0], exp) {
+		t.Fatalf("unexpected metric %+v want %+v", m[0], expected)
+	}
+}
+
+func TestVMRangeQuery(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/", func(_ http.ResponseWriter, _ *http.Request) {
+		t.Errorf("should not be called")
+	})
+	c := -1
+	mux.HandleFunc("/api/v1/query_range", func(w http.ResponseWriter, r *http.Request) {
+		c++
+		if r.Method != http.MethodPost {
+			t.Errorf("expected POST method got %s", r.Method)
+		}
+		if name, pass, _ := r.BasicAuth(); name != basicAuthName || pass != basicAuthPass {
+			t.Errorf("expected %s:%s as basic auth got %s:%s", basicAuthName, basicAuthPass, name, pass)
+		}
+		if r.URL.Query().Get("query") != query {
+			t.Errorf("expected %s in query param, got %s", query, r.URL.Query().Get("query"))
+		}
+		startTS := r.URL.Query().Get("start")
+		if startTS == "" {
+			t.Errorf("expected 'start' in query param, got nil instead")
+		}
+		if _, err := strconv.ParseInt(startTS, 10, 64); err != nil {
+			t.Errorf("failed to parse 'start' query param: %s", err)
+		}
+		endTS := r.URL.Query().Get("end")
+		if endTS == "" {
+			t.Errorf("expected 'end' in query param, got nil instead")
+		}
+		if _, err := strconv.ParseInt(endTS, 10, 64); err != nil {
+			t.Errorf("failed to parse 'end' query param: %s", err)
+		}
+		switch c {
+		case 0:
+			w.Write([]byte(`{"status":"success","data":{"resultType":"matrix","result":[{"metric":{"__name__":"vm_rows"},"values":[[1583786142,"13763"]]}]}}`))
+		}
+	})
+
+	srv := httptest.NewServer(mux)
+	defer srv.Close()
+
+	authCfg, err := promauth.NewConfig(".", nil, baCfg, "", "", nil, nil)
+	if err != nil {
+		t.Fatalf("unexpected: %s", err)
+	}
+	s := NewVMStorage(srv.URL, authCfg, time.Minute, 0, false, srv.Client())
+
+	p := NewPrometheusType()
+	pq := s.BuildWithParams(QuerierParams{DataSourceType: &p, EvaluationInterval: 15 * time.Second})
+
+	_, err = pq.QueryRange(ctx, query, time.Now(), time.Time{})
+	expectError(t, err, "is missing")
+
+	_, err = pq.QueryRange(ctx, query, time.Time{}, time.Now())
+	expectError(t, err, "is missing")
+
+	start, end := time.Now().Add(-time.Minute), time.Now()
+
+	m, err := pq.QueryRange(ctx, query, start, end)
+	if err != nil {
+		t.Fatalf("unexpected %s", err)
+	}
+	if len(m) != 1 {
+		t.Fatalf("expected 1 metric  got %d in %+v", len(m), m)
+	}
+	expected := Metric{
+		Labels:     []Label{{Value: "vm_rows", Name: "__name__"}},
+		Timestamps: []int64{1583786142},
+		Values:     []float64{13763},
+	}
+	if !reflect.DeepEqual(m[0], expected) {
+		t.Fatalf("unexpected metric %+v want %+v", m[0], expected)
+	}
+
+	g := NewGraphiteType()
+	gq := s.BuildWithParams(QuerierParams{DataSourceType: &g})
+
+	_, err = gq.QueryRange(ctx, queryRender, start, end)
+	expectError(t, err, "is not supported")
+}
+
+func TestRequestParams(t *testing.T) {
+	authCfg, err := promauth.NewConfig(".", nil, baCfg, "", "", nil, nil)
+	if err != nil {
+		t.Fatalf("unexpected: %s", err)
+	}
+	query := "up"
+	timestamp := time.Date(2001, 2, 3, 4, 5, 6, 0, time.UTC)
+	testCases := []struct {
+		name       string
+		queryRange bool
+		vm         *VMStorage
+		checkFn    func(t *testing.T, r *http.Request)
+	}{
+		{
+			"prometheus path",
+			false,
+			&VMStorage{
+				dataSourceType: NewPrometheusType(),
+			},
+			func(t *testing.T, r *http.Request) {
+				checkEqualString(t, prometheusInstantPath, r.URL.Path)
+			},
+		},
+		{
+			"prometheus prefix",
+			false,
+			&VMStorage{
+				dataSourceType:   NewPrometheusType(),
+				appendTypePrefix: true,
+			},
+			func(t *testing.T, r *http.Request) {
+				checkEqualString(t, prometheusPrefix+prometheusInstantPath, r.URL.Path)
+			},
+		},
+		{
+			"prometheus range path",
+			true,
+			&VMStorage{
+				dataSourceType: NewPrometheusType(),
+			},
+			func(t *testing.T, r *http.Request) {
+				checkEqualString(t, prometheusRangePath, r.URL.Path)
+			},
+		},
+		{
+			"prometheus range prefix",
+			true,
+			&VMStorage{
+				dataSourceType:   NewPrometheusType(),
+				appendTypePrefix: true,
+			},
+			func(t *testing.T, r *http.Request) {
+				checkEqualString(t, prometheusPrefix+prometheusRangePath, r.URL.Path)
+			},
+		},
+		{
+			"graphite path",
+			false,
+			&VMStorage{
+				dataSourceType: NewGraphiteType(),
+			},
+			func(t *testing.T, r *http.Request) {
+				checkEqualString(t, graphitePath, r.URL.Path)
+			},
+		},
+		{
+			"graphite prefix",
+			false,
+			&VMStorage{
+				dataSourceType:   NewGraphiteType(),
+				appendTypePrefix: true,
+			},
+			func(t *testing.T, r *http.Request) {
+				checkEqualString(t, graphitePrefix+graphitePath, r.URL.Path)
+			},
+		},
+		{
+			"default params",
+			false,
+			&VMStorage{},
+			func(t *testing.T, r *http.Request) {
+				exp := fmt.Sprintf("query=%s&time=%d", query, timestamp.Unix())
+				checkEqualString(t, exp, r.URL.RawQuery)
+			},
+		},
+		{
+			"default range params",
+			true,
+			&VMStorage{},
+			func(t *testing.T, r *http.Request) {
+				exp := fmt.Sprintf("end=%d&query=%s&start=%d", timestamp.Unix(), query, timestamp.Unix())
+				checkEqualString(t, exp, r.URL.RawQuery)
+			},
+		},
+		{
+			"basic auth",
+			false,
+			&VMStorage{authCfg: authCfg},
+			func(t *testing.T, r *http.Request) {
+				u, p, _ := r.BasicAuth()
+				checkEqualString(t, "foo", u)
+				checkEqualString(t, "bar", p)
+			},
+		},
+		{
+			"basic auth range",
+			true,
+			&VMStorage{authCfg: authCfg},
+			func(t *testing.T, r *http.Request) {
+				u, p, _ := r.BasicAuth()
+				checkEqualString(t, "foo", u)
+				checkEqualString(t, "bar", p)
+			},
+		},
+		{
+			"lookback",
+			false,
+			&VMStorage{
+				lookBack: time.Minute,
+			},
+			func(t *testing.T, r *http.Request) {
+				exp := fmt.Sprintf("query=%s&time=%d", query, timestamp.Add(-time.Minute).Unix())
+				checkEqualString(t, exp, r.URL.RawQuery)
+			},
+		},
+		{
+			"evaluation interval",
+			false,
+			&VMStorage{
+				evaluationInterval: 15 * time.Second,
+			},
+			func(t *testing.T, r *http.Request) {
+				evalInterval := 15 * time.Second
+				tt := timestamp.Truncate(evalInterval)
+				exp := fmt.Sprintf("query=%s&step=%v&time=%d", query, evalInterval, tt.Unix())
+				checkEqualString(t, exp, r.URL.RawQuery)
+			},
+		},
+		{
+			"lookback + evaluation interval",
+			false,
+			&VMStorage{
+				lookBack:           time.Minute,
+				evaluationInterval: 15 * time.Second,
+			},
+			func(t *testing.T, r *http.Request) {
+				evalInterval := 15 * time.Second
+				tt := timestamp.Add(-time.Minute)
+				tt = tt.Truncate(evalInterval)
+				exp := fmt.Sprintf("query=%s&step=%v&time=%d", query, evalInterval, tt.Unix())
+				checkEqualString(t, exp, r.URL.RawQuery)
+			},
+		},
+		{
+			"step override",
+			false,
+			&VMStorage{
+				queryStep: time.Minute,
+			},
+			func(t *testing.T, r *http.Request) {
+				exp := fmt.Sprintf("query=%s&step=%v&time=%d", query, time.Minute, timestamp.Unix())
+				checkEqualString(t, exp, r.URL.RawQuery)
+			},
+		},
+		{
+			"round digits",
+			false,
+			&VMStorage{
+				extraParams: []Param{{"round_digits", "10"}},
+			},
+			func(t *testing.T, r *http.Request) {
+				exp := fmt.Sprintf("query=%s&round_digits=10&time=%d", query, timestamp.Unix())
+				checkEqualString(t, exp, r.URL.RawQuery)
+			},
+		},
+		{
+			"extra labels",
+			false,
+			&VMStorage{
+				extraLabels: []string{
+					"env=prod",
+					"query=es=cape",
+				},
+			},
+			func(t *testing.T, r *http.Request) {
+				exp := fmt.Sprintf("extra_label=env%%3Dprod&extra_label=query%%3Des%%3Dcape&query=%s&time=%d", query, timestamp.Unix())
+				checkEqualString(t, exp, r.URL.RawQuery)
+			},
+		},
+		{
+			"extra labels range",
+			true,
+			&VMStorage{
+				extraLabels: []string{
+					"env=prod",
+					"query=es=cape",
+				},
+			},
+			func(t *testing.T, r *http.Request) {
+				exp := fmt.Sprintf("end=%d&extra_label=env%%3Dprod&extra_label=query%%3Des%%3Dcape&query=%s&start=%d",
+					timestamp.Unix(), query, timestamp.Unix())
+				checkEqualString(t, exp, r.URL.RawQuery)
+			},
+		},
+		{
+			"extra params",
+			false,
+			&VMStorage{
+				extraParams: []Param{
+					{Key: "nocache", Value: "1"},
+					{Key: "max_lookback", Value: "1h"},
+				},
+			},
+			func(t *testing.T, r *http.Request) {
+				exp := fmt.Sprintf("max_lookback=1h&nocache=1&query=%s&time=%d", query, timestamp.Unix())
+				checkEqualString(t, exp, r.URL.RawQuery)
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			req, err := tc.vm.newRequestPOST()
+			if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+			switch tc.vm.dataSourceType.name {
+			case "", prometheusType:
+				if tc.queryRange {
+					tc.vm.setPrometheusRangeReqParams(req, query, timestamp, timestamp)
+				} else {
+					tc.vm.setPrometheusInstantReqParams(req, query, timestamp)
+				}
+			case graphiteType:
+				tc.vm.setGraphiteReqParams(req, query, timestamp)
+			}
+			tc.checkFn(t, req)
+		})
+	}
+}
+
+func checkEqualString(t *testing.T, exp, got string) {
+	t.Helper()
+	if got != exp {
+		t.Errorf("expected to get %q; got %q", exp, got)
+	}
+}
+
+func expectError(t *testing.T, err error, exp string) {
+	t.Helper()
+	if err == nil {
+		t.Errorf("expected non-nil error")
+	}
+	if !strings.Contains(err.Error(), exp) {
+		t.Errorf("expected error %q to contain %q", err, exp)
+	}
+}

app/vmalert/deployment/Dockerfile

@@ -0,0 +1,8 @@
+ARG base_image
+FROM $base_image
+
+EXPOSE 8880
+
+ENTRYPOINT ["/vmalert-prod"]
+ARG src_binary
+COPY $src_binary ./vmalert-prod

app/vmalert/group.go

@@ -0,0 +1,404 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"hash/fnv"
+	"sync"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+// Group is an entity for grouping rules
+type Group struct {
+	mu          sync.RWMutex
+	Name        string
+	File        string
+	Rules       []Rule
+	Type        datasource.Type
+	Interval    time.Duration
+	Concurrency int
+	Checksum    string
+
+	ExtraFilterLabels map[string]string
+	Labels            map[string]string
+
+	doneCh     chan struct{}
+	finishedCh chan struct{}
+	// channel accepts new Group obj
+	// which supposed to update current group
+	updateCh chan *Group
+
+	metrics *groupMetrics
+}
+
+type groupMetrics struct {
+	iterationTotal    *counter
+	iterationDuration *summary
+}
+
+func newGroupMetrics(name, file string) *groupMetrics {
+	m := &groupMetrics{}
+	labels := fmt.Sprintf(`group=%q, file=%q`, name, file)
+	m.iterationTotal = getOrCreateCounter(fmt.Sprintf(`vmalert_iteration_total{%s}`, labels))
+	m.iterationDuration = getOrCreateSummary(fmt.Sprintf(`vmalert_iteration_duration_seconds{%s}`, labels))
+	return m
+}
+
+// merges group rule labels into result map
+// set2 has priority over set1.
+func mergeLabels(groupName, ruleName string, set1, set2 map[string]string) map[string]string {
+	r := map[string]string{}
+	for k, v := range set1 {
+		r[k] = v
+	}
+	for k, v := range set2 {
+		if prevV, ok := r[k]; ok {
+			logger.Infof("label %q=%q for rule %q.%q overwritten with external label %q=%q",
+				k, prevV, groupName, ruleName, k, v)
+		}
+		r[k] = v
+	}
+	return r
+}
+
+func newGroup(cfg config.Group, qb datasource.QuerierBuilder, defaultInterval time.Duration, labels map[string]string) *Group {
+	g := &Group{
+		Type:              cfg.Type,
+		Name:              cfg.Name,
+		File:              cfg.File,
+		Interval:          cfg.Interval.Duration(),
+		Concurrency:       cfg.Concurrency,
+		Checksum:          cfg.Checksum,
+		ExtraFilterLabels: cfg.ExtraFilterLabels,
+		Labels:            cfg.Labels,
+
+		doneCh:     make(chan struct{}),
+		finishedCh: make(chan struct{}),
+		updateCh:   make(chan *Group),
+	}
+	g.metrics = newGroupMetrics(g.Name, g.File)
+	if g.Interval == 0 {
+		g.Interval = defaultInterval
+	}
+	if g.Concurrency < 1 {
+		g.Concurrency = 1
+	}
+	rules := make([]Rule, len(cfg.Rules))
+	for i, r := range cfg.Rules {
+		var extraLabels map[string]string
+		// apply external labels
+		if len(labels) > 0 {
+			extraLabels = labels
+		}
+		// apply group labels, it has priority on external labels
+		if len(cfg.Labels) > 0 {
+			extraLabels = mergeLabels(g.Name, r.Name(), extraLabels, g.Labels)
+		}
+		// apply rules labels, it has priority on other labels
+		if len(extraLabels) > 0 {
+			r.Labels = mergeLabels(g.Name, r.Name(), extraLabels, r.Labels)
+		}
+
+		rules[i] = g.newRule(qb, r)
+	}
+	g.Rules = rules
+	return g
+}
+
+func (g *Group) newRule(qb datasource.QuerierBuilder, rule config.Rule) Rule {
+	if rule.Alert != "" {
+		return newAlertingRule(qb, g, rule)
+	}
+	return newRecordingRule(qb, g, rule)
+}
+
+// ID return unique group ID that consists of
+// rules file and group name
+func (g *Group) ID() uint64 {
+	hash := fnv.New64a()
+	hash.Write([]byte(g.File))
+	hash.Write([]byte("\xff"))
+	hash.Write([]byte(g.Name))
+	hash.Write([]byte(g.Type.Get()))
+	return hash.Sum64()
+}
+
+// Restore restores alerts state for group rules
+func (g *Group) Restore(ctx context.Context, qb datasource.QuerierBuilder, lookback time.Duration, labels map[string]string) error {
+	labels = mergeLabels(g.Name, "", labels, g.Labels)
+	for _, rule := range g.Rules {
+		rr, ok := rule.(*AlertingRule)
+		if !ok {
+			continue
+		}
+		if rr.For < 1 {
+			continue
+		}
+		// ignore g.ExtraFilterLabels on purpose, so it
+		// won't affect the restore procedure.
+		q := qb.BuildWithParams(datasource.QuerierParams{})
+		if err := rr.Restore(ctx, q, lookback, labels); err != nil {
+			return fmt.Errorf("error while restoring rule %q: %w", rule, err)
+		}
+	}
+	return nil
+}
+
+// updateWith updates existing group with
+// passed group object. This function ignores group
+// evaluation interval change. It supposed to be updated
+// in group.start function.
+// Not thread-safe.
+func (g *Group) updateWith(newGroup *Group) error {
+	rulesRegistry := make(map[uint64]Rule)
+	for _, nr := range newGroup.Rules {
+		rulesRegistry[nr.ID()] = nr
+	}
+
+	for i, or := range g.Rules {
+		nr, ok := rulesRegistry[or.ID()]
+		if !ok {
+			// old rule is not present in the new list
+			// so we mark it for removing
+			g.Rules[i].Close()
+			g.Rules[i] = nil
+			continue
+		}
+		if err := or.UpdateWith(nr); err != nil {
+			return err
+		}
+		delete(rulesRegistry, nr.ID())
+	}
+
+	var newRules []Rule
+	for _, r := range g.Rules {
+		if r == nil {
+			// skip nil rules
+			continue
+		}
+		newRules = append(newRules, r)
+	}
+	// add the rest of rules from registry
+	for _, nr := range rulesRegistry {
+		newRules = append(newRules, nr)
+	}
+	// note that g.Interval is not updated here
+	// so the value can be compared later in
+	// group.Start function
+	g.Type = newGroup.Type
+	g.Concurrency = newGroup.Concurrency
+	g.ExtraFilterLabels = newGroup.ExtraFilterLabels
+	g.Labels = newGroup.Labels
+	g.Checksum = newGroup.Checksum
+	g.Rules = newRules
+	return nil
+}
+
+func (g *Group) close() {
+	if g.doneCh == nil {
+		return
+	}
+	close(g.doneCh)
+	<-g.finishedCh
+
+	metrics.UnregisterMetric(g.metrics.iterationDuration.name)
+	metrics.UnregisterMetric(g.metrics.iterationTotal.name)
+	for _, rule := range g.Rules {
+		rule.Close()
+	}
+}
+
+var skipRandSleepOnGroupStart bool
+
+func (g *Group) start(ctx context.Context, nts []notifier.Notifier, rw *remotewrite.Client) {
+	defer func() { close(g.finishedCh) }()
+
+	// Spread group rules evaluation over time in order to reduce load on VictoriaMetrics.
+	if !skipRandSleepOnGroupStart {
+		randSleep := uint64(float64(g.Interval) * (float64(uint32(g.ID())) / (1 << 32)))
+		sleepOffset := uint64(time.Now().UnixNano()) % uint64(g.Interval)
+		if randSleep < sleepOffset {
+			randSleep += uint64(g.Interval)
+		}
+		randSleep -= sleepOffset
+		sleepTimer := time.NewTimer(time.Duration(randSleep))
+		select {
+		case <-ctx.Done():
+			sleepTimer.Stop()
+			return
+		case <-g.doneCh:
+			sleepTimer.Stop()
+			return
+		case <-sleepTimer.C:
+		}
+	}
+
+	logger.Infof("group %q started; interval=%v; concurrency=%d", g.Name, g.Interval, g.Concurrency)
+	e := &executor{rw: rw}
+	for _, nt := range nts {
+		ent := eNotifier{
+			Notifier:         nt,
+			alertsSent:       getOrCreateCounter(fmt.Sprintf("vmalert_alerts_sent_total{addr=%q}", nt.Addr())),
+			alertsSendErrors: getOrCreateCounter(fmt.Sprintf("vmalert_alerts_send_errors_total{addr=%q}", nt.Addr())),
+		}
+		e.notifiers = append(e.notifiers, ent)
+	}
+
+	t := time.NewTicker(g.Interval)
+	defer t.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			logger.Infof("group %q: context cancelled", g.Name)
+			return
+		case <-g.doneCh:
+			logger.Infof("group %q: received stop signal", g.Name)
+			return
+		case ng := <-g.updateCh:
+			g.mu.Lock()
+			err := g.updateWith(ng)
+			if err != nil {
+				logger.Errorf("group %q: failed to update: %s", g.Name, err)
+				g.mu.Unlock()
+				continue
+			}
+			if g.Interval != ng.Interval {
+				g.Interval = ng.Interval
+				t.Stop()
+				t = time.NewTicker(g.Interval)
+			}
+			g.mu.Unlock()
+			logger.Infof("group %q re-started; interval=%v; concurrency=%d", g.Name, g.Interval, g.Concurrency)
+		case <-t.C:
+			g.metrics.iterationTotal.Inc()
+			iterationStart := time.Now()
+			resolveDuration := getResolveDuration(g.Interval)
+			errs := e.execConcurrently(ctx, g.Rules, g.Concurrency, resolveDuration)
+			for err := range errs {
+				if err != nil {
+					logger.Errorf("group %q: %s", g.Name, err)
+				}
+			}
+
+			g.metrics.iterationDuration.UpdateDuration(iterationStart)
+		}
+	}
+}
+
+// resolveDuration for alerts is equal to 3 interval evaluations
+// so in case if vmalert stops sending updates for some reason,
+// notifier could automatically resolve the alert.
+func getResolveDuration(groupInterval time.Duration) time.Duration {
+	resolveInterval := groupInterval * 3
+	if *maxResolveDuration > 0 && (resolveInterval > *maxResolveDuration) {
+		return *maxResolveDuration
+	}
+	return resolveInterval
+}
+
+type executor struct {
+	notifiers []eNotifier
+	rw        *remotewrite.Client
+}
+
+type eNotifier struct {
+	notifier.Notifier
+	alertsSent       *counter
+	alertsSendErrors *counter
+}
+
+func (e *executor) execConcurrently(ctx context.Context, rules []Rule, concurrency int, resolveDuration time.Duration) chan error {
+	res := make(chan error, len(rules))
+	if concurrency == 1 {
+		// fast path
+		for _, rule := range rules {
+			res <- e.exec(ctx, rule, resolveDuration)
+		}
+		close(res)
+		return res
+	}
+
+	sem := make(chan struct{}, concurrency)
+	go func() {
+		wg := sync.WaitGroup{}
+		for _, rule := range rules {
+			sem <- struct{}{}
+			wg.Add(1)
+			go func(r Rule) {
+				res <- e.exec(ctx, r, resolveDuration)
+				<-sem
+				wg.Done()
+			}(rule)
+		}
+		wg.Wait()
+		close(res)
+	}()
+	return res
+}
+
+var (
+	alertsFired = metrics.NewCounter(`vmalert_alerts_fired_total`)
+
+	execTotal  = metrics.NewCounter(`vmalert_execution_total`)
+	execErrors = metrics.NewCounter(`vmalert_execution_errors_total`)
+
+	remoteWriteErrors = metrics.NewCounter(`vmalert_remotewrite_errors_total`)
+)
+
+func (e *executor) exec(ctx context.Context, rule Rule, resolveDuration time.Duration) error {
+	execTotal.Inc()
+
+	tss, err := rule.Exec(ctx)
+	if err != nil {
+		execErrors.Inc()
+		return fmt.Errorf("rule %q: failed to execute: %w", rule, err)
+	}
+
+	if len(tss) > 0 && e.rw != nil {
+		for _, ts := range tss {
+			if err := e.rw.Push(ts); err != nil {
+				remoteWriteErrors.Inc()
+				return fmt.Errorf("rule %q: remote write failure: %w", rule, err)
+			}
+		}
+	}
+
+	ar, ok := rule.(*AlertingRule)
+	if !ok {
+		return nil
+	}
+	var alerts []notifier.Alert
+	for _, a := range ar.alerts {
+		switch a.State {
+		case notifier.StateFiring:
+			a.End = time.Now().Add(resolveDuration)
+			alerts = append(alerts, *a)
+		case notifier.StateInactive:
+			// set End to execStart to notify
+			// that it was just resolved
+			a.End = time.Now()
+			alerts = append(alerts, *a)
+		}
+	}
+	if len(alerts) < 1 {
+		return nil
+	}
+
+	errGr := new(utils.ErrGroup)
+	for _, nt := range e.notifiers {
+		nt.alertsSent.Add(len(alerts))
+		if err := nt.Send(ctx, alerts); err != nil {
+			nt.alertsSendErrors.Inc()
+			errGr.Add(fmt.Errorf("rule %q: failed to send alerts: %w", rule, err))
+		}
+	}
+	return errGr.Err()
+}

app/vmalert/group_test.go

@@ -0,0 +1,262 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"sort"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+)
+
+func init() {
+	// Disable rand sleep on group start during tests in order to speed up test execution.
+	// Rand sleep is needed only in prod code.
+	skipRandSleepOnGroupStart = true
+}
+
+func TestUpdateWith(t *testing.T) {
+	testCases := []struct {
+		name         string
+		currentRules []config.Rule
+		newRules     []config.Rule
+	}{
+		{
+			"new rule",
+			nil,
+			[]config.Rule{{Alert: "bar"}},
+		},
+		{
+			"update alerting rule",
+			[]config.Rule{{
+				Alert: "foo",
+				Expr:  "up > 0",
+				For:   utils.NewPromDuration(time.Second),
+				Labels: map[string]string{
+					"bar": "baz",
+				},
+				Annotations: map[string]string{
+					"summary":     "{{ $value|humanize }}",
+					"description": "{{$labels}}",
+				},
+			}},
+			[]config.Rule{{
+				Alert: "foo",
+				Expr:  "up > 10",
+				For:   utils.NewPromDuration(time.Second),
+				Labels: map[string]string{
+					"baz": "bar",
+				},
+				Annotations: map[string]string{
+					"summary": "none",
+				},
+			}},
+		},
+		{
+			"update recording rule",
+			[]config.Rule{{
+				Record: "foo",
+				Expr:   "max(up)",
+				Labels: map[string]string{
+					"bar": "baz",
+				},
+			}},
+			[]config.Rule{{
+				Record: "foo",
+				Expr:   "min(up)",
+				Labels: map[string]string{
+					"baz": "bar",
+				},
+			}},
+		},
+		{
+			"empty rule",
+			[]config.Rule{{Alert: "foo"}, {Record: "bar"}},
+			nil,
+		},
+		{
+			"multiple rules",
+			[]config.Rule{
+				{Alert: "bar"},
+				{Alert: "baz"},
+				{Alert: "foo"},
+			},
+			[]config.Rule{
+				{Alert: "baz"},
+				{Record: "foo"},
+			},
+		},
+		{
+			"replace rule",
+			[]config.Rule{{Alert: "foo1"}},
+			[]config.Rule{{Alert: "foo2"}},
+		},
+		{
+			"replace multiple rules",
+			[]config.Rule{
+				{Alert: "foo1"},
+				{Record: "foo2"},
+				{Alert: "foo3"},
+			},
+			[]config.Rule{
+				{Alert: "foo3"},
+				{Alert: "foo4"},
+				{Record: "foo5"},
+			},
+		},
+		{
+			"update datasource type",
+			[]config.Rule{
+				{Alert: "foo1", Type: datasource.NewPrometheusType()},
+				{Alert: "foo3", Type: datasource.NewGraphiteType()},
+			},
+			[]config.Rule{
+				{Alert: "foo1", Type: datasource.NewGraphiteType()},
+				{Alert: "foo10", Type: datasource.NewPrometheusType()},
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			g := &Group{Name: "test"}
+			qb := &fakeQuerier{}
+			for _, r := range tc.currentRules {
+				r.ID = config.HashRule(r)
+				g.Rules = append(g.Rules, g.newRule(qb, r))
+			}
+
+			ng := &Group{Name: "test"}
+			for _, r := range tc.newRules {
+				r.ID = config.HashRule(r)
+				ng.Rules = append(ng.Rules, ng.newRule(qb, r))
+			}
+
+			err := g.updateWith(ng)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if len(g.Rules) != len(tc.newRules) {
+				t.Fatalf("expected to have %d rules; got: %d",
+					len(g.Rules), len(tc.newRules))
+			}
+			sort.Slice(g.Rules, func(i, j int) bool {
+				return g.Rules[i].ID() < g.Rules[j].ID()
+			})
+			sort.Slice(ng.Rules, func(i, j int) bool {
+				return ng.Rules[i].ID() < ng.Rules[j].ID()
+			})
+			for i, r := range g.Rules {
+				got, want := r, ng.Rules[i]
+				if got.ID() != want.ID() {
+					t.Fatalf("expected to have rule %q; got %q", want, got)
+				}
+				if err := compareRules(t, got, want); err != nil {
+					t.Fatalf("comparsion error: %s", err)
+				}
+			}
+		})
+	}
+}
+
+func TestGroupStart(t *testing.T) {
+	// TODO: make parsing from string instead of file
+	groups, err := config.Parse([]string{"config/testdata/rules1-good.rules"}, true, true)
+	if err != nil {
+		t.Fatalf("failed to parse rules: %s", err)
+	}
+	const evalInterval = time.Millisecond
+	fs := &fakeQuerier{}
+	fn := &fakeNotifier{}
+
+	g := newGroup(groups[0], fs, evalInterval, map[string]string{"cluster": "east-1"})
+	g.Concurrency = 2
+
+	const inst1, inst2, job = "foo", "bar", "baz"
+	m1 := metricWithLabels(t, "instance", inst1, "job", job)
+	m2 := metricWithLabels(t, "instance", inst2, "job", job)
+
+	r := g.Rules[0].(*AlertingRule)
+	alert1, err := r.newAlert(m1, time.Now(), nil)
+	if err != nil {
+		t.Fatalf("faield to create alert: %s", err)
+	}
+	alert1.State = notifier.StateFiring
+	// add external label
+	alert1.Labels["cluster"] = "east-1"
+	// add rule labels - see config/testdata/rules1-good.rules
+	alert1.Labels["label"] = "bar"
+	alert1.Labels["host"] = inst1
+	alert1.ID = hash(m1)
+
+	alert2, err := r.newAlert(m2, time.Now(), nil)
+	if err != nil {
+		t.Fatalf("faield to create alert: %s", err)
+	}
+	alert2.State = notifier.StateFiring
+	// add external label
+	alert2.Labels["cluster"] = "east-1"
+	// add rule labels - see config/testdata/rules1-good.rules
+	alert2.Labels["label"] = "bar"
+	alert2.Labels["host"] = inst2
+	alert2.ID = hash(m2)
+
+	finished := make(chan struct{})
+	fs.add(m1)
+	fs.add(m2)
+	go func() {
+		g.start(context.Background(), []notifier.Notifier{fn}, nil)
+		close(finished)
+	}()
+
+	// wait for multiple evals
+	time.Sleep(20 * evalInterval)
+
+	gotAlerts := fn.getAlerts()
+	expectedAlerts := []notifier.Alert{*alert1, *alert2}
+	compareAlerts(t, expectedAlerts, gotAlerts)
+
+	// reset previous data
+	fs.reset()
+	// and set only one datapoint for response
+	fs.add(m1)
+
+	// wait for multiple evals
+	time.Sleep(20 * evalInterval)
+
+	gotAlerts = fn.getAlerts()
+	expectedAlerts = []notifier.Alert{*alert1}
+	compareAlerts(t, expectedAlerts, gotAlerts)
+
+	g.close()
+	<-finished
+}
+
+func TestResolveDuration(t *testing.T) {
+	testCases := []struct {
+		groupInterval time.Duration
+		maxDuration   time.Duration
+		expected      time.Duration
+	}{
+		{time.Minute, 0, 3 * time.Minute},
+		{3 * time.Minute, 0, 9 * time.Minute},
+		{time.Minute, 2 * time.Minute, 2 * time.Minute},
+		{0, 0, 0},
+	}
+	defaultResolveDuration := *maxResolveDuration
+	defer func() { *maxResolveDuration = defaultResolveDuration }()
+	for _, tc := range testCases {
+		t.Run(fmt.Sprintf("%v-%v-%v", tc.groupInterval, tc.expected, tc.maxDuration), func(t *testing.T) {
+			*maxResolveDuration = tc.maxDuration
+			got := getResolveDuration(tc.groupInterval)
+			if got != tc.expected {
+				t.Errorf("expected to have %v; got %v", tc.expected, got)
+			}
+		})
+	}
+}

app/vmalert/helpers_test.go

@@ -0,0 +1,252 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"sort"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+)
+
+type fakeQuerier struct {
+	sync.Mutex
+	metrics []datasource.Metric
+	err     error
+}
+
+func (fq *fakeQuerier) setErr(err error) {
+	fq.Lock()
+	fq.err = err
+	fq.Unlock()
+}
+
+func (fq *fakeQuerier) reset() {
+	fq.Lock()
+	fq.err = nil
+	fq.metrics = fq.metrics[:0]
+	fq.Unlock()
+}
+
+func (fq *fakeQuerier) add(metrics ...datasource.Metric) {
+	fq.Lock()
+	fq.metrics = append(fq.metrics, metrics...)
+	fq.Unlock()
+}
+
+func (fq *fakeQuerier) BuildWithParams(_ datasource.QuerierParams) datasource.Querier {
+	return fq
+}
+
+func (fq *fakeQuerier) QueryRange(ctx context.Context, q string, _, _ time.Time) ([]datasource.Metric, error) {
+	return fq.Query(ctx, q)
+}
+
+func (fq *fakeQuerier) Query(_ context.Context, _ string) ([]datasource.Metric, error) {
+	fq.Lock()
+	defer fq.Unlock()
+	if fq.err != nil {
+		return nil, fq.err
+	}
+	cp := make([]datasource.Metric, len(fq.metrics))
+	copy(cp, fq.metrics)
+	return cp, nil
+}
+
+type fakeNotifier struct {
+	sync.Mutex
+	alerts []notifier.Alert
+}
+
+func (*fakeNotifier) Addr() string { return "" }
+func (fn *fakeNotifier) Send(_ context.Context, alerts []notifier.Alert) error {
+	fn.Lock()
+	defer fn.Unlock()
+	fn.alerts = alerts
+	return nil
+}
+
+func (fn *fakeNotifier) getAlerts() []notifier.Alert {
+	fn.Lock()
+	defer fn.Unlock()
+	return fn.alerts
+}
+
+func metricWithValueAndLabels(t *testing.T, value float64, labels ...string) datasource.Metric {
+	return metricWithValuesAndLabels(t, []float64{value}, labels...)
+}
+
+func metricWithValuesAndLabels(t *testing.T, values []float64, labels ...string) datasource.Metric {
+	t.Helper()
+	m := metricWithLabels(t, labels...)
+	m.Values = values
+	for i := range values {
+		m.Timestamps = append(m.Timestamps, int64(i))
+	}
+	return m
+}
+
+func metricWithLabels(t *testing.T, labels ...string) datasource.Metric {
+	t.Helper()
+	if len(labels) == 0 || len(labels)%2 != 0 {
+		t.Fatalf("expected to get even number of labels")
+	}
+	m := datasource.Metric{Values: []float64{1}, Timestamps: []int64{1}}
+	for i := 0; i < len(labels); i += 2 {
+		m.Labels = append(m.Labels, datasource.Label{
+			Name:  labels[i],
+			Value: labels[i+1],
+		})
+	}
+	return m
+}
+
+func compareGroups(t *testing.T, a, b *Group) {
+	t.Helper()
+	if a.Name != b.Name {
+		t.Fatalf("expected group name %q; got %q", a.Name, b.Name)
+	}
+	if a.File != b.File {
+		t.Fatalf("expected group %q file name %q; got %q", a.Name, a.File, b.File)
+	}
+	if a.Interval != b.Interval {
+		t.Fatalf("expected group %q interval %v; got %v", a.Name, a.Interval, b.Interval)
+	}
+	if len(a.Rules) != len(b.Rules) {
+		t.Fatalf("expected group %s to have %d rules; got: %d",
+			a.Name, len(a.Rules), len(b.Rules))
+	}
+	for i, r := range a.Rules {
+		got, want := r, b.Rules[i]
+		if a.ID() != b.ID() {
+			t.Fatalf("expected to have rule %q; got %q", want.ID(), got.ID())
+		}
+		if err := compareRules(t, want, got); err != nil {
+			t.Fatalf("comparsion error: %s", err)
+		}
+	}
+}
+
+func compareRules(t *testing.T, a, b Rule) error {
+	t.Helper()
+	switch v := a.(type) {
+	case *AlertingRule:
+		br, ok := b.(*AlertingRule)
+		if !ok {
+			return fmt.Errorf("rule %q supposed to be of type AlertingRule", b.ID())
+		}
+		return compareAlertingRules(t, v, br)
+	case *RecordingRule:
+		br, ok := b.(*RecordingRule)
+		if !ok {
+			return fmt.Errorf("rule %q supposed to be of type RecordingRule", b.ID())
+		}
+		return compareRecordingRules(t, v, br)
+	default:
+		return fmt.Errorf("unexpected rule type received %T", a)
+	}
+}
+
+func compareRecordingRules(t *testing.T, a, b *RecordingRule) error {
+	t.Helper()
+	if a.Expr != b.Expr {
+		return fmt.Errorf("expected to have expression %q; got %q", a.Expr, b.Expr)
+	}
+	if !reflect.DeepEqual(a.Labels, b.Labels) {
+		return fmt.Errorf("expected to have labels %#v; got %#v", a.Labels, b.Labels)
+	}
+	return nil
+}
+
+func compareAlertingRules(t *testing.T, a, b *AlertingRule) error {
+	t.Helper()
+	if a.Expr != b.Expr {
+		return fmt.Errorf("expected to have expression %q; got %q", a.Expr, b.Expr)
+	}
+	if a.For != b.For {
+		return fmt.Errorf("expected to have for %q; got %q", a.For, b.For)
+	}
+	if !reflect.DeepEqual(a.Annotations, b.Annotations) {
+		return fmt.Errorf("expected to have annotations %#v; got %#v", a.Annotations, b.Annotations)
+	}
+	if !reflect.DeepEqual(a.Labels, b.Labels) {
+		return fmt.Errorf("expected to have labels %#v; got %#v", a.Labels, b.Labels)
+	}
+	if a.Type.String() != b.Type.String() {
+		return fmt.Errorf("expected to have Type %#v; got %#v", a.Type.String(), b.Type.String())
+	}
+	return nil
+}
+
+func compareTimeSeries(t *testing.T, a, b []prompbmarshal.TimeSeries) error {
+	t.Helper()
+	if len(a) != len(b) {
+		return fmt.Errorf("expected number of timeseries %d; got %d", len(a), len(b))
+	}
+	for i := range a {
+		expTS, gotTS := a[i], b[i]
+		if len(expTS.Samples) != len(gotTS.Samples) {
+			return fmt.Errorf("expected number of samples %d; got %d", len(expTS.Samples), len(gotTS.Samples))
+		}
+		for i, exp := range expTS.Samples {
+			got := gotTS.Samples[i]
+			if got.Value != exp.Value {
+				return fmt.Errorf("expected value %.2f; got %.2f", exp.Value, got.Value)
+			}
+			// timestamp validation isn't always correct for now.
+			// this must be improved with time mock.
+			/*if got.Timestamp != exp.Timestamp {
+				return fmt.Errorf("expected timestamp %d; got %d", exp.Timestamp, got.Timestamp)
+			}*/
+		}
+		if len(expTS.Labels) != len(gotTS.Labels) {
+			return fmt.Errorf("expected number of labels %d; got %d", len(expTS.Labels), len(gotTS.Labels))
+		}
+		for i, exp := range expTS.Labels {
+			got := gotTS.Labels[i]
+			if got.Name != exp.Name {
+				return fmt.Errorf("expected label name %q; got %q", exp.Name, got.Name)
+			}
+			if got.Value != exp.Value {
+				return fmt.Errorf("expected label value %q; got %q", exp.Value, got.Value)
+			}
+		}
+	}
+	return nil
+}
+
+func compareAlerts(t *testing.T, as, bs []notifier.Alert) {
+	t.Helper()
+	if len(as) != len(bs) {
+		t.Fatalf("expected to have length %d; got %d", len(as), len(bs))
+	}
+	sort.Slice(as, func(i, j int) bool {
+		return as[i].ID < as[j].ID
+	})
+	sort.Slice(bs, func(i, j int) bool {
+		return bs[i].ID < bs[j].ID
+	})
+	for i := range as {
+		a, b := as[i], bs[i]
+		if a.Name != b.Name {
+			t.Fatalf("expected t have Name %q; got %q", a.Name, b.Name)
+		}
+		if a.State != b.State {
+			t.Fatalf("expected t have State %q; got %q", a.State, b.State)
+		}
+		if a.Value != b.Value {
+			t.Fatalf("expected t have Value %f; got %f", a.Value, b.Value)
+		}
+		if !reflect.DeepEqual(a.Annotations, b.Annotations) {
+			t.Fatalf("expected to have annotations %#v; got %#v", a.Annotations, b.Annotations)
+		}
+		if !reflect.DeepEqual(a.Labels, b.Labels) {
+			t.Fatalf("expected to have labels %#v; got %#v", a.Labels, b.Labels)
+		}
+	}
+}

app/vmalert/main.go

@@ -0,0 +1,311 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/remoteread"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/buildinfo"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envflag"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rulePath = flagutil.NewArray("rule", `Path to the file with alert rules.
+Supports patterns. Flag can be specified multiple times.
+Examples:
+ -rule="/path/to/file". Path to a single file with alerting rules
+ -rule="dir/*.yaml" -rule="/*.yaml". Relative path to all .yaml files in "dir" folder,
+absolute path to all .yaml files in root.
+Rule files may contain %{ENV_VAR} placeholders, which are substituted by the corresponding env vars.`)
+
+	rulesCheckInterval = flag.Duration("rule.configCheckInterval", 0, "Interval for checking for changes in '-rule' files. "+
+		"By default the checking is disabled. Send SIGHUP signal in order to force config check for changes")
+
+	httpListenAddr     = flag.String("httpListenAddr", ":8880", "Address to listen for http connections")
+	evaluationInterval = flag.Duration("evaluationInterval", time.Minute, "How often to evaluate the rules")
+
+	validateTemplates   = flag.Bool("rule.validateTemplates", true, "Whether to validate annotation and label templates")
+	validateExpressions = flag.Bool("rule.validateExpressions", true, "Whether to validate rules expressions via MetricsQL engine")
+	maxResolveDuration  = flag.Duration("rule.maxResolveDuration", 0, "Limits the maximum duration for automatic alert expiration, "+
+		"which is by default equal to 3 evaluation intervals of the parent group.")
+	externalURL         = flag.String("external.url", "", "External URL is used as alert's source for sent alerts to the notifier")
+	externalAlertSource = flag.String("external.alert.source", "", `External Alert Source allows to override the Source link for alerts sent to AlertManager for cases where you want to build a custom link to Grafana, Prometheus or any other service.
+eg. 'explore?orgId=1&left=[\"now-1h\",\"now\",\"VictoriaMetrics\",{\"expr\": \"{{$expr|quotesEscape|crlfEscape|queryEscape}}\"},{\"mode\":\"Metrics\"},{\"ui\":[true,true,true,\"none\"]}]'.If empty '/api/v1/:groupID/alertID/status' is used`)
+	externalLabels = flagutil.NewArray("external.label", "Optional label in the form 'name=value' to add to all generated recording rules and alerts. "+
+		"Pass multiple -label flags in order to add multiple label sets.")
+
+	remoteReadLookBack = flag.Duration("remoteRead.lookback", time.Hour, "Lookback defines how far to look into past for alerts timeseries."+
+		" For example, if lookback=1h then range from now() to now()-1h will be scanned.")
+	remoteReadIgnoreRestoreErrors = flag.Bool("remoteRead.ignoreRestoreErrors", true, "Whether to ignore errors from remote storage when restoring alerts state on startup.")
+
+	disableAlertGroupLabel = flag.Bool("disableAlertgroupLabel", false, "Whether to disable adding group's name as label to generated alerts and time series.")
+
+	dryRun = flag.Bool("dryRun", false, "Whether to check only config files without running vmalert. The rules file are validated. The `-rule` flag must be specified.")
+)
+
+func main() {
+	// Write flags and help message to stdout, since it is easier to grep or pipe.
+	flag.CommandLine.SetOutput(os.Stdout)
+	flag.Usage = usage
+	envflag.Parse()
+	buildinfo.Init()
+	logger.Init()
+
+	if *dryRun {
+		u, _ := url.Parse("https://victoriametrics.com/")
+		notifier.InitTemplateFunc(u)
+		groups, err := config.Parse(*rulePath, true, true)
+		if err != nil {
+			logger.Fatalf("failed to parse %q: %s", *rulePath, err)
+		}
+		if len(groups) == 0 {
+			logger.Fatalf("No rules for validation. Please specify path to file(s) with alerting and/or recording rules using `-rule` flag")
+		}
+		return
+	}
+	if *replayFrom != "" || *replayTo != "" {
+		rw, err := remotewrite.Init(context.Background())
+		if err != nil {
+			logger.Fatalf("failed to init remoteWrite: %s", err)
+		}
+		eu, err := getExternalURL(*externalURL, *httpListenAddr, httpserver.IsTLS())
+		if err != nil {
+			logger.Fatalf("failed to init `external.url`: %s", err)
+		}
+		notifier.InitTemplateFunc(eu)
+		groupsCfg, err := config.Parse(*rulePath, *validateTemplates, *validateExpressions)
+		if err != nil {
+			logger.Fatalf("cannot parse configuration file: %s", err)
+		}
+		// prevent queries from caching and boundaries aligning
+		// when querying VictoriaMetrics datasource.
+		noCache := datasource.Param{Key: "nocache", Value: "1"}
+		q, err := datasource.Init([]datasource.Param{noCache})
+		if err != nil {
+			logger.Fatalf("failed to init datasource: %s", err)
+		}
+		if err := replay(groupsCfg, q, rw); err != nil {
+			logger.Fatalf("replay failed: %s", err)
+		}
+		return
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	manager, err := newManager(ctx)
+	if err != nil {
+		logger.Fatalf("failed to init: %s", err)
+	}
+
+	logger.Infof("reading rules configuration file from %q", strings.Join(*rulePath, ";"))
+	groupsCfg, err := config.Parse(*rulePath, *validateTemplates, *validateExpressions)
+	if err != nil {
+		logger.Fatalf("cannot parse configuration file: %s", err)
+	}
+
+	if err := manager.start(ctx, groupsCfg); err != nil {
+		logger.Fatalf("failed to start: %s", err)
+	}
+
+	go configReload(ctx, manager, groupsCfg)
+
+	rh := &requestHandler{m: manager}
+	go httpserver.Serve(*httpListenAddr, rh.handler)
+
+	sig := procutil.WaitForSigterm()
+	logger.Infof("service received signal %s", sig)
+	if err := httpserver.Stop(*httpListenAddr); err != nil {
+		logger.Fatalf("cannot stop the webservice: %s", err)
+	}
+	cancel()
+	manager.close()
+}
+
+var (
+	configReloads      = metrics.NewCounter(`vmalert_config_last_reload_total`)
+	configReloadErrors = metrics.NewCounter(`vmalert_config_last_reload_errors_total`)
+	configSuccess      = metrics.NewCounter(`vmalert_config_last_reload_successful`)
+	configTimestamp    = metrics.NewCounter(`vmalert_config_last_reload_success_timestamp_seconds`)
+)
+
+func newManager(ctx context.Context) (*manager, error) {
+	q, err := datasource.Init(nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to init datasource: %w", err)
+	}
+	eu, err := getExternalURL(*externalURL, *httpListenAddr, httpserver.IsTLS())
+	if err != nil {
+		return nil, fmt.Errorf("failed to init `external.url`: %w", err)
+	}
+	notifier.InitTemplateFunc(eu)
+	aug, err := getAlertURLGenerator(eu, *externalAlertSource, *validateTemplates)
+	if err != nil {
+		return nil, fmt.Errorf("failed to init `external.alert.source`: %w", err)
+	}
+	nts, err := notifier.Init(aug)
+	if err != nil {
+		return nil, fmt.Errorf("failed to init notifier: %w", err)
+	}
+
+	manager := &manager{
+		groups:         make(map[uint64]*Group),
+		querierBuilder: q,
+		notifiers:      nts,
+		labels:         map[string]string{},
+	}
+	rw, err := remotewrite.Init(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to init remoteWrite: %w", err)
+	}
+	manager.rw = rw
+
+	rr, err := remoteread.Init()
+	if err != nil {
+		return nil, fmt.Errorf("failed to init remoteRead: %w", err)
+	}
+	manager.rr = rr
+
+	for _, s := range *externalLabels {
+		if len(s) == 0 {
+			continue
+		}
+		n := strings.IndexByte(s, '=')
+		if n < 0 {
+			return nil, fmt.Errorf("missing '=' in `-label`. It must contain label in the form `name=value`; got %q", s)
+		}
+		manager.labels[s[:n]] = s[n+1:]
+	}
+	return manager, nil
+}
+
+func getExternalURL(externalURL, httpListenAddr string, isSecure bool) (*url.URL, error) {
+	if externalURL != "" {
+		return url.Parse(externalURL)
+	}
+	hname, err := os.Hostname()
+	if err != nil {
+		return nil, err
+	}
+	port := ""
+	if ipport := strings.Split(httpListenAddr, ":"); len(ipport) > 1 {
+		port = ":" + ipport[1]
+	}
+	schema := "http://"
+	if isSecure {
+		schema = "https://"
+	}
+	return url.Parse(fmt.Sprintf("%s%s%s", schema, hname, port))
+}
+
+func getAlertURLGenerator(externalURL *url.URL, externalAlertSource string, validateTemplate bool) (notifier.AlertURLGenerator, error) {
+	if externalAlertSource == "" {
+		return func(alert notifier.Alert) string {
+			return fmt.Sprintf("%s/api/v1/%s/%s/status", externalURL, strconv.FormatUint(alert.GroupID, 10), strconv.FormatUint(alert.ID, 10))
+		}, nil
+	}
+	if validateTemplate {
+		if err := notifier.ValidateTemplates(map[string]string{
+			"tpl": externalAlertSource,
+		}); err != nil {
+			return nil, fmt.Errorf("error validating source template %s: %w", externalAlertSource, err)
+		}
+	}
+	m := map[string]string{
+		"tpl": externalAlertSource,
+	}
+	return func(alert notifier.Alert) string {
+		templated, err := alert.ExecTemplate(nil, m)
+		if err != nil {
+			logger.Errorf("can not exec source template %s", err)
+		}
+		return fmt.Sprintf("%s/%s", externalURL, templated["tpl"])
+	}, nil
+}
+
+func usage() {
+	const s = `
+vmalert processes alerts and recording rules.
+
+See the docs at https://docs.victoriametrics.com/vmalert.html .
+`
+	flagutil.Usage(s)
+}
+
+func configReload(ctx context.Context, m *manager, groupsCfg []config.Group) {
+	// Register SIGHUP handler for config re-read just before manager.start call.
+	// This guarantees that the config will be re-read if the signal arrives during manager.start call.
+	// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1240
+	sighupCh := procutil.NewSighupChan()
+
+	var configCheckCh <-chan time.Time
+	if *rulesCheckInterval > 0 {
+		ticker := time.NewTicker(*rulesCheckInterval)
+		configCheckCh = ticker.C
+		defer ticker.Stop()
+	}
+
+	// init reload metrics with positive values to improve alerting conditions
+	configSuccess.Set(1)
+	configTimestamp.Set(fasttime.UnixTimestamp())
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-sighupCh:
+			logger.Infof("SIGHUP received. Going to reload rules %q ...", *rulePath)
+			configReloads.Inc()
+		case <-configCheckCh:
+		}
+		newGroupsCfg, err := config.Parse(*rulePath, *validateTemplates, *validateExpressions)
+		if err != nil {
+			configReloadErrors.Inc()
+			configSuccess.Set(0)
+			logger.Errorf("cannot parse configuration file: %s", err)
+			continue
+		}
+		if configsEqual(newGroupsCfg, groupsCfg) {
+			// set success to 1 since previous reload
+			// could have been unsuccessful
+			configSuccess.Set(1)
+			// config didn't change - skip it
+			continue
+		}
+		groupsCfg = newGroupsCfg
+		if err := m.update(ctx, groupsCfg, false); err != nil {
+			configReloadErrors.Inc()
+			configSuccess.Set(0)
+			logger.Errorf("error while reloading rules: %s", err)
+			continue
+		}
+		configSuccess.Set(1)
+		configTimestamp.Set(fasttime.UnixTimestamp())
+		logger.Infof("Rules reloaded successfully from %q", *rulePath)
+	}
+}
+
+func configsEqual(a, b []config.Group) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i].Checksum != b[i].Checksum {
+			return false
+		}
+	}
+	return true
+}

app/vmalert/main_test.go

@@ -0,0 +1,156 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"io/ioutil"
+	"net/url"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
+)
+
+func TestGetExternalURL(t *testing.T) {
+	expURL := "https://vicotriametrics.com/path"
+	u, err := getExternalURL(expURL, "", false)
+	if err != nil {
+		t.Errorf("unexpected error %s", err)
+	}
+	if u.String() != expURL {
+		t.Errorf("unexpected url want %s, got %s", expURL, u.String())
+	}
+	h, _ := os.Hostname()
+	expURL = fmt.Sprintf("https://%s:4242", h)
+	u, err = getExternalURL("", "0.0.0.0:4242", true)
+	if err != nil {
+		t.Errorf("unexpected error %s", err)
+	}
+	if u.String() != expURL {
+		t.Errorf("unexpected url want %s, got %s", expURL, u.String())
+	}
+}
+
+func TestGetAlertURLGenerator(t *testing.T) {
+	testAlert := notifier.Alert{GroupID: 42, ID: 2, Value: 4}
+	u, _ := url.Parse("https://victoriametrics.com/path")
+	fn, err := getAlertURLGenerator(u, "", false)
+	if err != nil {
+		t.Errorf("unexpected error %s", err)
+	}
+	if exp := "https://victoriametrics.com/path/api/v1/42/2/status"; exp != fn(testAlert) {
+		t.Errorf("unexpected url want %s, got %s", exp, fn(testAlert))
+	}
+	_, err = getAlertURLGenerator(nil, "foo?{{invalid}}", true)
+	if err == nil {
+		t.Errorf("expected tempalte validation error got nil")
+	}
+	fn, err = getAlertURLGenerator(u, "foo?query={{$value}}", true)
+	if err != nil {
+		t.Errorf("unexpected error %s", err)
+	}
+	if exp := "https://victoriametrics.com/path/foo?query=4"; exp != fn(testAlert) {
+		t.Errorf("unexpected url want %s, got %s", exp, fn(testAlert))
+	}
+}
+
+func TestConfigReload(t *testing.T) {
+	originalRulePath := *rulePath
+	defer func() {
+		*rulePath = originalRulePath
+	}()
+
+	const (
+		rules1 = `
+groups:
+  - name: group-1
+    rules:
+      - alert: ExampleAlertAlwaysFiring
+        expr: sum by(job) (up == 1)
+      - record: handler:requests:rate5m 
+        expr: sum(rate(prometheus_http_requests_total[5m])) by (handler)
+`
+		rules2 = `
+groups:
+  - name: group-1
+    rules:
+      - alert: ExampleAlertAlwaysFiring
+        expr: sum by(job) (up == 1)
+  - name: group-2
+    rules:
+      - record: handler:requests:rate5m 
+        expr: sum(rate(prometheus_http_requests_total[5m])) by (handler)
+`
+	)
+
+	f, err := ioutil.TempFile("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	writeToFile(t, f.Name(), rules1)
+
+	*rulesCheckInterval = 200 * time.Millisecond
+	*rulePath = []string{f.Name()}
+	ctx, cancel := context.WithCancel(context.Background())
+
+	m := &manager{
+		querierBuilder: &fakeQuerier{},
+		groups:         make(map[uint64]*Group),
+		labels:         map[string]string{},
+	}
+
+	syncCh := make(chan struct{})
+	go func() {
+		configReload(ctx, m, nil)
+		close(syncCh)
+	}()
+
+	lenLocked := func(m *manager) int {
+		m.groupsMu.RLock()
+		defer m.groupsMu.RUnlock()
+		return len(m.groups)
+	}
+
+	time.Sleep(*rulesCheckInterval * 2)
+	groupsLen := lenLocked(m)
+	if groupsLen != 1 {
+		t.Fatalf("expected to have exactly 1 group loaded; got %d", groupsLen)
+	}
+
+	writeToFile(t, f.Name(), rules2)
+	time.Sleep(*rulesCheckInterval * 2)
+	groupsLen = lenLocked(m)
+	if groupsLen != 2 {
+		fmt.Println(m.groups)
+		t.Fatalf("expected to have exactly 2 groups loaded; got %d", groupsLen)
+	}
+
+	writeToFile(t, f.Name(), rules1)
+	procutil.SelfSIGHUP()
+	time.Sleep(*rulesCheckInterval / 2)
+	groupsLen = lenLocked(m)
+	if groupsLen != 1 {
+		t.Fatalf("expected to have exactly 1 group loaded; got %d", groupsLen)
+	}
+
+	writeToFile(t, f.Name(), `corrupted`)
+	procutil.SelfSIGHUP()
+	time.Sleep(*rulesCheckInterval / 2)
+	groupsLen = lenLocked(m)
+	if groupsLen != 1 { // should remain unchanged
+		t.Fatalf("expected to have exactly 1 group loaded; got %d", groupsLen)
+	}
+
+	cancel()
+	<-syncCh
+}
+
+func writeToFile(t *testing.T, file, b string) {
+	t.Helper()
+	err := ioutil.WriteFile(file, []byte(b), 0644)
+	if err != nil {
+		t.Fatal(err)
+	}
+}

app/vmalert/manager.go

@@ -0,0 +1,162 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+)
+
+// manager controls group states
+type manager struct {
+	querierBuilder datasource.QuerierBuilder
+	notifiers      []notifier.Notifier
+
+	rw *remotewrite.Client
+	// remote read builder.
+	rr datasource.QuerierBuilder
+
+	wg     sync.WaitGroup
+	labels map[string]string
+
+	groupsMu sync.RWMutex
+	groups   map[uint64]*Group
+}
+
+// AlertAPI generates APIAlert object from alert by its ID(hash)
+func (m *manager) AlertAPI(gID, aID uint64) (*APIAlert, error) {
+	m.groupsMu.RLock()
+	defer m.groupsMu.RUnlock()
+
+	g, ok := m.groups[gID]
+	if !ok {
+		return nil, fmt.Errorf("can't find group with id %q", gID)
+	}
+	for _, rule := range g.Rules {
+		ar, ok := rule.(*AlertingRule)
+		if !ok {
+			continue
+		}
+		if apiAlert := ar.AlertAPI(aID); apiAlert != nil {
+			return apiAlert, nil
+		}
+	}
+	return nil, fmt.Errorf("can't find alert with id %q in group %q", aID, g.Name)
+}
+
+func (m *manager) start(ctx context.Context, groupsCfg []config.Group) error {
+	return m.update(ctx, groupsCfg, true)
+}
+
+func (m *manager) close() {
+	if m.rw != nil {
+		err := m.rw.Close()
+		if err != nil {
+			logger.Fatalf("cannot stop the remotewrite: %s", err)
+		}
+	}
+	m.wg.Wait()
+}
+
+func (m *manager) startGroup(ctx context.Context, group *Group, restore bool) error {
+	if restore && m.rr != nil {
+		err := group.Restore(ctx, m.rr, *remoteReadLookBack, m.labels)
+		if err != nil {
+			if !*remoteReadIgnoreRestoreErrors {
+				return fmt.Errorf("failed to restore state for group %q: %w", group.Name, err)
+			}
+			logger.Errorf("error while restoring state for group %q: %s", group.Name, err)
+		}
+	}
+
+	m.wg.Add(1)
+	id := group.ID()
+	go func() {
+		group.start(ctx, m.notifiers, m.rw)
+		m.wg.Done()
+	}()
+	m.groups[id] = group
+	return nil
+}
+
+func (m *manager) update(ctx context.Context, groupsCfg []config.Group, restore bool) error {
+	groupsRegistry := make(map[uint64]*Group)
+	for _, cfg := range groupsCfg {
+		ng := newGroup(cfg, m.querierBuilder, *evaluationInterval, m.labels)
+		groupsRegistry[ng.ID()] = ng
+	}
+
+	type updateItem struct {
+		old *Group
+		new *Group
+	}
+	var toUpdate []updateItem
+
+	m.groupsMu.Lock()
+	for _, og := range m.groups {
+		ng, ok := groupsRegistry[og.ID()]
+		if !ok {
+			// old group is not present in new list,
+			// so must be stopped and deleted
+			og.close()
+			delete(m.groups, og.ID())
+			og = nil
+			continue
+		}
+		delete(groupsRegistry, ng.ID())
+		if og.Checksum != ng.Checksum {
+			toUpdate = append(toUpdate, updateItem{old: og, new: ng})
+		}
+	}
+	for _, ng := range groupsRegistry {
+		if err := m.startGroup(ctx, ng, restore); err != nil {
+			return err
+		}
+	}
+	m.groupsMu.Unlock()
+
+	if len(toUpdate) > 0 {
+		var wg sync.WaitGroup
+		for _, item := range toUpdate {
+			wg.Add(1)
+			go func(old *Group, new *Group) {
+				old.updateCh <- new
+				wg.Done()
+			}(item.old, item.new)
+		}
+		wg.Wait()
+	}
+	return nil
+}
+
+func (g *Group) toAPI() APIGroup {
+	g.mu.RLock()
+	defer g.mu.RUnlock()
+
+	ag := APIGroup{
+		// encode as string to avoid rounding
+		ID: fmt.Sprintf("%d", g.ID()),
+
+		Name:              g.Name,
+		Type:              g.Type.String(),
+		File:              g.File,
+		Interval:          g.Interval.String(),
+		Concurrency:       g.Concurrency,
+		ExtraFilterLabels: g.ExtraFilterLabels,
+		Labels:            g.Labels,
+	}
+	for _, r := range g.Rules {
+		switch v := r.(type) {
+		case *AlertingRule:
+			ag.AlertingRules = append(ag.AlertingRules, v.RuleAPI())
+		case *RecordingRule:
+			ag.RecordingRules = append(ag.RecordingRules, v.RuleAPI())
+		}
+	}
+	return ag
+}

app/vmalert/manager_test.go

@@ -0,0 +1,286 @@
+package main
+
+import (
+	"context"
+	"math/rand"
+	"net/url"
+	"os"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+)
+
+func TestMain(m *testing.M) {
+	u, _ := url.Parse("https://victoriametrics.com/path")
+	notifier.InitTemplateFunc(u)
+	os.Exit(m.Run())
+}
+
+// TestManagerEmptyRulesDir tests
+// successful cases of
+// starting with empty rules folder
+func TestManagerEmptyRulesDir(t *testing.T) {
+	m := &manager{groups: make(map[uint64]*Group)}
+	cfg := loadCfg(t, []string{"foo/bar"}, true, true)
+	if err := m.update(context.Background(), cfg, false); err != nil {
+		t.Fatalf("expected to load succesfully with empty rules dir; got err instead: %v", err)
+	}
+}
+
+// TestManagerUpdateConcurrent supposed to test concurrent
+// execution of configuration update.
+// Should be executed with -race flag
+func TestManagerUpdateConcurrent(t *testing.T) {
+	m := &manager{
+		groups:         make(map[uint64]*Group),
+		querierBuilder: &fakeQuerier{},
+		notifiers:      []notifier.Notifier{&fakeNotifier{}},
+	}
+	paths := []string{
+		"config/testdata/dir/rules0-good.rules",
+		"config/testdata/dir/rules0-bad.rules",
+		"config/testdata/dir/rules1-good.rules",
+		"config/testdata/dir/rules1-bad.rules",
+		"config/testdata/rules0-good.rules",
+		"config/testdata/rules1-good.rules",
+		"config/testdata/rules2-good.rules",
+	}
+	evalInterval := *evaluationInterval
+	defer func() { *evaluationInterval = evalInterval }()
+	*evaluationInterval = time.Millisecond
+	cfg := loadCfg(t, []string{paths[0]}, true, true)
+	if err := m.start(context.Background(), cfg); err != nil {
+		t.Fatalf("failed to start: %s", err)
+	}
+
+	const workers = 500
+	const iterations = 10
+	wg := sync.WaitGroup{}
+	wg.Add(workers)
+	for i := 0; i < workers; i++ {
+		go func() {
+			defer wg.Done()
+			for i := 0; i < iterations; i++ {
+				rnd := rand.Intn(len(paths))
+				cfg, err := config.Parse([]string{paths[rnd]}, true, true)
+				if err != nil { // update can fail and this is expected
+					continue
+				}
+				_ = m.update(context.Background(), cfg, false)
+			}
+		}()
+	}
+	wg.Wait()
+}
+
+// TestManagerUpdate tests sequential configuration
+// updates.
+func TestManagerUpdate(t *testing.T) {
+	const defaultEvalInterval = time.Second * 30
+	currentEvalInterval := *evaluationInterval
+	*evaluationInterval = defaultEvalInterval
+	defer func() {
+		*evaluationInterval = currentEvalInterval
+	}()
+
+	var (
+		VMRows = &AlertingRule{
+			Name: "VMRows",
+			Expr: "vm_rows > 0",
+			For:  10 * time.Second,
+			Labels: map[string]string{
+				"label": "bar",
+				"host":  "{{ $labels.instance }}",
+			},
+			Annotations: map[string]string{
+				"summary":     "{{ $value|humanize }}",
+				"description": "{{$labels}}",
+			},
+		}
+		Conns = &AlertingRule{
+			Name: "Conns",
+			Expr: "sum(vm_tcplistener_conns) by(instance) > 1",
+			Annotations: map[string]string{
+				"summary":     "Too high connection number for {{$labels.instance}}",
+				"description": "It is {{ $value }} connections for {{$labels.instance}}",
+			},
+		}
+		ExampleAlertAlwaysFiring = &AlertingRule{
+			Name: "ExampleAlertAlwaysFiring",
+			Expr: "sum by(job) (up == 1)",
+		}
+		ExampleAlertGraphite = &AlertingRule{
+			Name: "up graphite",
+			Expr: "filterSeries(time('host.1',20),'>','0')",
+			Type: datasource.NewGraphiteType(),
+			For:  defaultEvalInterval,
+		}
+		ExampleAlertGraphite2 = &AlertingRule{
+			Name: "up",
+			Expr: "filterSeries(time('host.2',20),'>','0')",
+			Type: datasource.NewGraphiteType(),
+			For:  defaultEvalInterval,
+		}
+	)
+
+	testCases := []struct {
+		name       string
+		initPath   string
+		updatePath string
+		want       []*Group
+	}{
+		{
+			name:       "update good rules",
+			initPath:   "config/testdata/rules0-good.rules",
+			updatePath: "config/testdata/dir/rules1-good.rules",
+			want: []*Group{
+				{
+					File:     "config/testdata/dir/rules1-good.rules",
+					Name:     "duplicatedGroupDiffFiles",
+					Type:     datasource.NewPrometheusType(),
+					Interval: defaultEvalInterval,
+					Rules: []Rule{
+						&AlertingRule{
+							Name:   "VMRows",
+							Expr:   "vm_rows > 0",
+							For:    5 * time.Minute,
+							Labels: map[string]string{"dc": "gcp", "label": "bar"},
+							Annotations: map[string]string{
+								"summary":     "{{ $value }}",
+								"description": "{{$labels}}",
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			name:       "update good rules from 1 to 2 groups",
+			initPath:   "config/testdata/dir/rules1-good.rules",
+			updatePath: "config/testdata/rules0-good.rules",
+			want: []*Group{
+				{
+					File:     "config/testdata/rules0-good.rules",
+					Name:     "groupGorSingleAlert",
+					Type:     datasource.NewPrometheusType(),
+					Rules:    []Rule{VMRows},
+					Interval: defaultEvalInterval,
+				},
+				{
+					File:     "config/testdata/rules0-good.rules",
+					Interval: defaultEvalInterval,
+					Type:     datasource.NewPrometheusType(),
+					Name:     "TestGroup", Rules: []Rule{
+						Conns,
+						ExampleAlertAlwaysFiring,
+					}},
+			},
+		},
+		{
+			name:       "update with one bad rule file",
+			initPath:   "config/testdata/rules0-good.rules",
+			updatePath: "config/testdata/dir/rules2-bad.rules",
+			want: []*Group{
+				{
+					File:     "config/testdata/rules0-good.rules",
+					Name:     "groupGorSingleAlert",
+					Type:     datasource.NewPrometheusType(),
+					Interval: defaultEvalInterval,
+					Rules:    []Rule{VMRows},
+				},
+				{
+					File:     "config/testdata/rules0-good.rules",
+					Interval: defaultEvalInterval,
+					Name:     "TestGroup",
+					Type:     datasource.NewPrometheusType(),
+					Rules: []Rule{
+						Conns,
+						ExampleAlertAlwaysFiring,
+					}},
+			},
+		},
+		{
+			name:       "update empty dir rules from 0 to 2 groups",
+			initPath:   "config/testdata/empty/*",
+			updatePath: "config/testdata/rules0-good.rules",
+			want: []*Group{
+				{
+					File:     "config/testdata/rules0-good.rules",
+					Name:     "groupGorSingleAlert",
+					Type:     datasource.NewPrometheusType(),
+					Interval: defaultEvalInterval,
+					Rules:    []Rule{VMRows},
+				},
+				{
+					File:     "config/testdata/rules0-good.rules",
+					Interval: defaultEvalInterval,
+					Type:     datasource.NewPrometheusType(),
+					Name:     "TestGroup", Rules: []Rule{
+						Conns,
+						ExampleAlertAlwaysFiring,
+					},
+				},
+			},
+		},
+		{
+			name:       "update prometheus to graphite type",
+			initPath:   "config/testdata/dir/rules-update0-good.rules",
+			updatePath: "config/testdata/dir/rules-update1-good.rules",
+			want: []*Group{
+				{
+					File:     "config/testdata/dir/rules-update1-good.rules",
+					Interval: defaultEvalInterval,
+					Type:     datasource.NewGraphiteType(),
+					Name:     "TestUpdateGroup",
+					Rules: []Rule{
+						ExampleAlertGraphite2,
+						ExampleAlertGraphite,
+					},
+				},
+			},
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			ctx, cancel := context.WithCancel(context.TODO())
+			m := &manager{groups: make(map[uint64]*Group), querierBuilder: &fakeQuerier{}}
+
+			cfgInit := loadCfg(t, []string{tc.initPath}, true, true)
+			if err := m.update(ctx, cfgInit, false); err != nil {
+				t.Fatalf("failed to complete initial rules update: %s", err)
+			}
+
+			cfgUpdate, err := config.Parse([]string{tc.updatePath}, true, true)
+			if err == nil { // update can fail and that's expected
+				_ = m.update(ctx, cfgUpdate, false)
+			}
+			if len(tc.want) != len(m.groups) {
+				t.Fatalf("\nwant number of groups: %d;\ngot: %d ", len(tc.want), len(m.groups))
+			}
+
+			for _, wantG := range tc.want {
+				gotG, ok := m.groups[wantG.ID()]
+				if !ok {
+					t.Fatalf("expected to have group %q", wantG.Name)
+				}
+				compareGroups(t, wantG, gotG)
+			}
+
+			cancel()
+			m.close()
+		})
+	}
+}
+
+func loadCfg(t *testing.T, path []string, validateAnnotations, validateExpressions bool) []config.Group {
+	t.Helper()
+	cfg, err := config.Parse(path, validateAnnotations, validateExpressions)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return cfg
+}

app/vmalert/metrics.go

@@ -0,0 +1,39 @@
+package main
+
+import "github.com/VictoriaMetrics/metrics"
+
+type gauge struct {
+	name string
+	*metrics.Gauge
+}
+
+func getOrCreateGauge(name string, f func() float64) *gauge {
+	return &gauge{
+		name:  name,
+		Gauge: metrics.GetOrCreateGauge(name, f),
+	}
+}
+
+type counter struct {
+	name string
+	*metrics.Counter
+}
+
+func getOrCreateCounter(name string) *counter {
+	return &counter{
+		name:    name,
+		Counter: metrics.GetOrCreateCounter(name),
+	}
+}
+
+type summary struct {
+	name string
+	*metrics.Summary
+}
+
+func getOrCreateSummary(name string) *summary {
+	return &summary{
+		name:    name,
+		Summary: metrics.GetOrCreateSummary(name),
+	}
+}

app/vmalert/multiarch/Dockerfile

@@ -0,0 +1,12 @@
+# See https://medium.com/on-docker/use-multi-stage-builds-to-inject-ca-certs-ad1e8f01de1b
+ARG certs_image
+ARG root_image
+FROM $certs_image as certs
+RUN apk --update --no-cache add ca-certificates
+
+FROM $root_image
+COPY --from=certs /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
+EXPOSE 8880
+ENTRYPOINT ["/vmalert-prod"]
+ARG TARGETARCH
+COPY vmalert-${TARGETARCH}-prod ./vmalert-prod

app/vmalert/notifier/alert.go

@@ -0,0 +1,127 @@
+package notifier
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"strings"
+	"text/template"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+)
+
+// Alert the triggered alert
+// TODO: Looks like alert name isn't unique
+type Alert struct {
+	// GroupID contains the ID of the parent rules group
+	GroupID uint64
+	// Name represents Alert name
+	Name string
+	// Labels is the list of label-value pairs attached to the Alert
+	Labels map[string]string
+	// Annotations is the list of annotations generated on Alert evaluation
+	Annotations map[string]string
+	// State represents the current state of the Alert
+	State AlertState
+	// Expr contains expression that was executed to generate the Alert
+	Expr string
+	// Start defines the moment of time when Alert has triggered
+	Start time.Time
+	// End defines the moment of time when Alert supposed to expire
+	End time.Time
+	// Value stores the value returned from evaluating expression from Expr field
+	Value float64
+	// ID is the unique identifer for the Alert
+	ID uint64
+}
+
+// AlertState type indicates the Alert state
+type AlertState int
+
+const (
+	// StateInactive is the state of an alert that is neither firing nor pending.
+	StateInactive AlertState = iota
+	// StatePending is the state of an alert that has been active for less than
+	// the configured threshold duration.
+	StatePending
+	// StateFiring is the state of an alert that has been active for longer than
+	// the configured threshold duration.
+	StateFiring
+)
+
+// String stringer for AlertState
+func (as AlertState) String() string {
+	switch as {
+	case StateFiring:
+		return "firing"
+	case StatePending:
+		return "pending"
+	}
+	return "inactive"
+}
+
+// AlertTplData is used to execute templating
+type AlertTplData struct {
+	Labels map[string]string
+	Value  float64
+	Expr   string
+}
+
+const tplHeader = `{{ $value := .Value }}{{ $labels := .Labels }}{{ $expr := .Expr }}`
+
+// ExecTemplate executes the Alert template for given
+// map of annotations.
+// Every alert could have a different datasource, so function
+// requires a queryFunction as an argument.
+func (a *Alert) ExecTemplate(q QueryFn, annotations map[string]string) (map[string]string, error) {
+	tplData := AlertTplData{Value: a.Value, Labels: a.Labels, Expr: a.Expr}
+	return templateAnnotations(annotations, tplData, funcsWithQuery(q))
+}
+
+// ExecTemplate executes the given template for given annotations map.
+func ExecTemplate(q QueryFn, annotations map[string]string, tpl AlertTplData) (map[string]string, error) {
+	return templateAnnotations(annotations, tpl, funcsWithQuery(q))
+}
+
+// ValidateTemplates validate annotations for possible template error, uses empty data for template population
+func ValidateTemplates(annotations map[string]string) error {
+	_, err := templateAnnotations(annotations, AlertTplData{
+		Labels: map[string]string{},
+		Value:  0,
+	}, tmplFunc)
+	return err
+}
+
+func templateAnnotations(annotations map[string]string, data AlertTplData, funcs template.FuncMap) (map[string]string, error) {
+	var builder strings.Builder
+	var buf bytes.Buffer
+	eg := new(utils.ErrGroup)
+	r := make(map[string]string, len(annotations))
+	for key, text := range annotations {
+		buf.Reset()
+		builder.Reset()
+		builder.Grow(len(tplHeader) + len(text))
+		builder.WriteString(tplHeader)
+		builder.WriteString(text)
+		if err := templateAnnotation(&buf, builder.String(), data, funcs); err != nil {
+			r[key] = text
+			eg.Add(fmt.Errorf("key %q, template %q: %w", key, text, err))
+			continue
+		}
+		r[key] = buf.String()
+	}
+	return r, eg.Err()
+}
+
+func templateAnnotation(dst io.Writer, text string, data AlertTplData, funcs template.FuncMap) error {
+	t := template.New("").Funcs(funcs).Option("missingkey=zero")
+	tpl, err := t.Parse(text)
+	if err != nil {
+		return fmt.Errorf("error parsing annotation: %w", err)
+	}
+	if err = tpl.Execute(dst, data); err != nil {
+		return fmt.Errorf("error evaluating annotation template: %w", err)
+	}
+	return nil
+}

app/vmalert/notifier/alert_test.go

@@ -0,0 +1,116 @@
+package notifier
+
+import (
+	"testing"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+)
+
+func TestAlert_ExecTemplate(t *testing.T) {
+	testCases := []struct {
+		name        string
+		alert       *Alert
+		annotations map[string]string
+		expTpl      map[string]string
+	}{
+		{
+			name:        "empty-alert",
+			alert:       &Alert{},
+			annotations: map[string]string{},
+			expTpl:      map[string]string{},
+		},
+		{
+			name: "no-template",
+			alert: &Alert{
+				Value: 1e4,
+				Labels: map[string]string{
+					"instance": "localhost",
+				},
+			},
+			annotations: map[string]string{},
+			expTpl:      map[string]string{},
+		},
+		{
+			name: "label-template",
+			alert: &Alert{
+				Value: 1e4,
+				Labels: map[string]string{
+					"job":      "staging",
+					"instance": "localhost",
+				},
+			},
+			annotations: map[string]string{
+				"summary":     "Too high connection number for {{$labels.instance}} for job {{$labels.job}}",
+				"description": "It is {{ $value }} connections for {{$labels.instance}}",
+			},
+			expTpl: map[string]string{
+				"summary":     "Too high connection number for localhost for job staging",
+				"description": "It is 10000 connections for localhost",
+			},
+		},
+		{
+			name: "expression-template",
+			alert: &Alert{
+				Expr: `vm_rows{"label"="bar"}>0`,
+			},
+			annotations: map[string]string{
+				"exprEscapedQuery": "{{ $expr|quotesEscape|queryEscape }}",
+				"exprEscapedPath":  "{{ $expr|quotesEscape|pathEscape }}",
+			},
+			expTpl: map[string]string{
+				"exprEscapedQuery": "vm_rows%7B%5C%22label%5C%22%3D%5C%22bar%5C%22%7D%3E0",
+				"exprEscapedPath":  "vm_rows%7B%5C%22label%5C%22=%5C%22bar%5C%22%7D%3E0",
+			},
+		},
+		{
+			name:  "query",
+			alert: &Alert{Expr: `vm_rows{"label"="bar"}>0`},
+			annotations: map[string]string{
+				"summary": `{{ query "foo" | first | value }}`,
+				"desc":    `{{ range query "bar" }}{{ . | label "foo" }} {{ . | value }};{{ end }}`,
+			},
+			expTpl: map[string]string{
+				"summary": "1",
+				"desc":    "bar 1;garply 2;",
+			},
+		},
+	}
+
+	qFn := func(q string) ([]datasource.Metric, error) {
+		return []datasource.Metric{
+			{
+				Labels: []datasource.Label{
+					{Name: "foo", Value: "bar"},
+					{Name: "baz", Value: "qux"},
+				},
+				Values:     []float64{1},
+				Timestamps: []int64{1},
+			},
+			{
+				Labels: []datasource.Label{
+					{Name: "foo", Value: "garply"},
+					{Name: "baz", Value: "fred"},
+				},
+				Values:     []float64{2},
+				Timestamps: []int64{1},
+			},
+		}, nil
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			tpl, err := tc.alert.ExecTemplate(qFn, tc.annotations)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(tpl) != len(tc.expTpl) {
+				t.Fatalf("expected %d elements; got %d", len(tc.expTpl), len(tpl))
+			}
+			for k := range tc.expTpl {
+				got, exp := tpl[k], tc.expTpl[k]
+				if got != exp {
+					t.Fatalf("expected %q=%q; got %q=%q", k, exp, k, got)
+				}
+			}
+		})
+	}
+}

app/vmalert/notifier/alertmanager.go

@@ -0,0 +1,73 @@
+package notifier
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"strings"
+)
+
+// AlertManager represents integration provider with Prometheus alert manager
+// https://github.com/prometheus/alertmanager
+type AlertManager struct {
+	addr          string
+	alertURL      string
+	basicAuthUser string
+	basicAuthPass string
+	argFunc       AlertURLGenerator
+	client        *http.Client
+}
+
+// Addr returns address where alerts are sent.
+func (am AlertManager) Addr() string { return am.addr }
+
+// Send an alert or resolve message
+func (am *AlertManager) Send(ctx context.Context, alerts []Alert) error {
+	b := &bytes.Buffer{}
+	writeamRequest(b, alerts, am.argFunc)
+
+	req, err := http.NewRequest("POST", am.alertURL, b)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json; charset=utf-8")
+	req = req.WithContext(ctx)
+	if am.basicAuthPass != "" {
+		req.SetBasicAuth(am.basicAuthUser, am.basicAuthPass)
+	}
+	resp, err := am.client.Do(req)
+	if err != nil {
+		return err
+	}
+
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode != http.StatusOK {
+		body, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			return fmt.Errorf("failed to read response from %q: %w", am.alertURL, err)
+		}
+		return fmt.Errorf("invalid SC %d from %q; response body: %s", resp.StatusCode, am.alertURL, string(body))
+	}
+	return nil
+}
+
+// AlertURLGenerator returns URL to single alert by given name
+type AlertURLGenerator func(Alert) string
+
+const alertManagerPath = "/api/v2/alerts"
+
+// NewAlertManager is a constructor for AlertManager
+func NewAlertManager(alertManagerURL, user, pass string, fn AlertURLGenerator, c *http.Client) *AlertManager {
+	url := strings.TrimSuffix(alertManagerURL, "/") + alertManagerPath
+	return &AlertManager{
+		addr:          alertManagerURL,
+		alertURL:      url,
+		argFunc:       fn,
+		client:        c,
+		basicAuthUser: user,
+		basicAuthPass: pass,
+	}
+}

app/vmalert/notifier/alertmanager_request.qtpl

@@ -0,0 +1,33 @@
+{% import (
+    "time"
+) %}
+{% stripspace %}
+
+{% func amRequest(alerts []Alert, generatorURL func(Alert) string) %}
+[
+{% for i, alert := range alerts %}
+{
+    "startsAt":{%q= alert.Start.Format(time.RFC3339Nano) %},
+    "generatorURL": {%q= generatorURL(alert) %},
+    {% if !alert.End.IsZero() %}
+    "endsAt":{%q= alert.End.Format(time.RFC3339Nano) %},
+    {% endif %}
+    "labels": {
+        "alertname":{%q= alert.Name %}
+        {% for k,v := range alert.Labels %}
+            ,{%q= k %}:{%q= v %}
+        {% endfor %}
+    },
+    "annotations": {
+        {% code c := len(alert.Annotations) %}
+        {% for k,v := range alert.Annotations %}
+          {% code c = c-1 %}
+          {%q= k %}:{%q= v %}{% if c > 0 %},{% endif %}
+        {% endfor %}
+    }
+}
+{% if i != len(alerts)-1 %},{% endif %}
+{% endfor %}
+]
+{% endfunc %}
+{% endstripspace %}

app/vmalert/notifier/alertmanager_request.qtpl.go

@@ -0,0 +1,130 @@
+// Code generated by qtc from "alertmanager_request.qtpl". DO NOT EDIT.
+// See https://github.com/valyala/quicktemplate for details.
+
+//line app/vmalert/notifier/alertmanager_request.qtpl:1
+package notifier
+
+//line app/vmalert/notifier/alertmanager_request.qtpl:1
+import (
+	"time"
+)
+
+//line app/vmalert/notifier/alertmanager_request.qtpl:6
+import (
+	qtio422016 "io"
+
+	qt422016 "github.com/valyala/quicktemplate"
+)
+
+//line app/vmalert/notifier/alertmanager_request.qtpl:6
+var (
+	_ = qtio422016.Copy
+	_ = qt422016.AcquireByteBuffer
+)
+
+//line app/vmalert/notifier/alertmanager_request.qtpl:6
+func streamamRequest(qw422016 *qt422016.Writer, alerts []Alert, generatorURL func(Alert) string) {
+//line app/vmalert/notifier/alertmanager_request.qtpl:6
+	qw422016.N().S(`[`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:8
+	for i, alert := range alerts {
+//line app/vmalert/notifier/alertmanager_request.qtpl:8
+		qw422016.N().S(`{"startsAt":`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:10
+		qw422016.N().Q(alert.Start.Format(time.RFC3339Nano))
+//line app/vmalert/notifier/alertmanager_request.qtpl:10
+		qw422016.N().S(`,"generatorURL":`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:11
+		qw422016.N().Q(generatorURL(alert))
+//line app/vmalert/notifier/alertmanager_request.qtpl:11
+		qw422016.N().S(`,`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:12
+		if !alert.End.IsZero() {
+//line app/vmalert/notifier/alertmanager_request.qtpl:12
+			qw422016.N().S(`"endsAt":`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:13
+			qw422016.N().Q(alert.End.Format(time.RFC3339Nano))
+//line app/vmalert/notifier/alertmanager_request.qtpl:13
+			qw422016.N().S(`,`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:14
+		}
+//line app/vmalert/notifier/alertmanager_request.qtpl:14
+		qw422016.N().S(`"labels": {"alertname":`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:16
+		qw422016.N().Q(alert.Name)
+//line app/vmalert/notifier/alertmanager_request.qtpl:17
+		for k, v := range alert.Labels {
+//line app/vmalert/notifier/alertmanager_request.qtpl:17
+			qw422016.N().S(`,`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:18
+			qw422016.N().Q(k)
+//line app/vmalert/notifier/alertmanager_request.qtpl:18
+			qw422016.N().S(`:`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:18
+			qw422016.N().Q(v)
+//line app/vmalert/notifier/alertmanager_request.qtpl:19
+		}
+//line app/vmalert/notifier/alertmanager_request.qtpl:19
+		qw422016.N().S(`},"annotations": {`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:22
+		c := len(alert.Annotations)
+
+//line app/vmalert/notifier/alertmanager_request.qtpl:23
+		for k, v := range alert.Annotations {
+//line app/vmalert/notifier/alertmanager_request.qtpl:24
+			c = c - 1
+
+//line app/vmalert/notifier/alertmanager_request.qtpl:25
+			qw422016.N().Q(k)
+//line app/vmalert/notifier/alertmanager_request.qtpl:25
+			qw422016.N().S(`:`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:25
+			qw422016.N().Q(v)
+//line app/vmalert/notifier/alertmanager_request.qtpl:25
+			if c > 0 {
+//line app/vmalert/notifier/alertmanager_request.qtpl:25
+				qw422016.N().S(`,`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:25
+			}
+//line app/vmalert/notifier/alertmanager_request.qtpl:26
+		}
+//line app/vmalert/notifier/alertmanager_request.qtpl:26
+		qw422016.N().S(`}}`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:29
+		if i != len(alerts)-1 {
+//line app/vmalert/notifier/alertmanager_request.qtpl:29
+			qw422016.N().S(`,`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:29
+		}
+//line app/vmalert/notifier/alertmanager_request.qtpl:30
+	}
+//line app/vmalert/notifier/alertmanager_request.qtpl:30
+	qw422016.N().S(`]`)
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+}
+
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+func writeamRequest(qq422016 qtio422016.Writer, alerts []Alert, generatorURL func(Alert) string) {
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+	qw422016 := qt422016.AcquireWriter(qq422016)
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+	streamamRequest(qw422016, alerts, generatorURL)
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+	qt422016.ReleaseWriter(qw422016)
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+}
+
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+func amRequest(alerts []Alert, generatorURL func(Alert) string) string {
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+	qb422016 := qt422016.AcquireByteBuffer()
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+	writeamRequest(qb422016, alerts, generatorURL)
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+	qs422016 := string(qb422016.B)
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+	qt422016.ReleaseByteBuffer(qb422016)
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+	return qs422016
+//line app/vmalert/notifier/alertmanager_request.qtpl:32
+}

app/vmalert/notifier/alertmanager_test.go

@@ -0,0 +1,99 @@
+package notifier
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"testing"
+	"time"
+)
+
+func TestAlertManager_Addr(t *testing.T) {
+	const addr = "http://localhost"
+	am := NewAlertManager(addr, "", "", nil, nil)
+	if am.Addr() != addr {
+		t.Errorf("expected to have %q; got %q", addr, am.Addr())
+	}
+}
+
+func TestAlertManager_Send(t *testing.T) {
+	const baUser, baPass = "foo", "bar"
+	mux := http.NewServeMux()
+	mux.HandleFunc("/", func(_ http.ResponseWriter, _ *http.Request) {
+		t.Errorf("should not be called")
+	})
+	c := -1
+	mux.HandleFunc(alertManagerPath, func(w http.ResponseWriter, r *http.Request) {
+		user, pass, ok := r.BasicAuth()
+		if !ok {
+			t.Errorf("unauthorized request")
+		}
+		if user != baUser || pass != baPass {
+			t.Errorf("wrong creds %q:%q; expected %q:%q",
+				user, pass, baUser, baPass)
+		}
+		c++
+		if r.Method != http.MethodPost {
+			t.Errorf("expected POST method got %s", r.Method)
+		}
+		switch c {
+		case 0:
+			conn, _, _ := w.(http.Hijacker).Hijack()
+			_ = conn.Close()
+		case 1:
+			w.WriteHeader(500)
+		case 2:
+			var a []struct {
+				Labels       map[string]string `json:"labels"`
+				StartsAt     time.Time         `json:"startsAt"`
+				EndAt        time.Time         `json:"endsAt"`
+				Annotations  map[string]string `json:"annotations"`
+				GeneratorURL string            `json:"generatorURL"`
+			}
+			if err := json.NewDecoder(r.Body).Decode(&a); err != nil {
+				t.Errorf("can not unmarshal data into alert %s", err)
+				t.FailNow()
+			}
+			if len(a) != 1 {
+				t.Errorf("expected 1 alert in array got %d", len(a))
+			}
+			if a[0].GeneratorURL != "0/0" {
+				t.Errorf("expected 0/0 as generatorURL got %s", a[0].GeneratorURL)
+			}
+			if a[0].Labels["alertname"] != "alert0" {
+				t.Errorf("expected alert0 as alert name got %s", a[0].Labels["alertname"])
+			}
+			if a[0].StartsAt.IsZero() {
+				t.Errorf("expected non-zero start time")
+			}
+			if a[0].EndAt.IsZero() {
+				t.Errorf("expected non-zero end time")
+			}
+		}
+	})
+	srv := httptest.NewServer(mux)
+	defer srv.Close()
+	am := NewAlertManager(srv.URL, baUser, baPass, func(alert Alert) string {
+		return strconv.FormatUint(alert.GroupID, 10) + "/" + strconv.FormatUint(alert.ID, 10)
+	}, srv.Client())
+	if err := am.Send(context.Background(), []Alert{{}, {}}); err == nil {
+		t.Error("expected connection error got nil")
+	}
+	if err := am.Send(context.Background(), []Alert{}); err == nil {
+		t.Error("expected wrong http code error got nil")
+	}
+	if err := am.Send(context.Background(), []Alert{{
+		GroupID:     0,
+		Name:        "alert0",
+		Start:       time.Now().UTC(),
+		End:         time.Now().UTC(),
+		Annotations: map[string]string{"a": "b", "c": "d", "e": "f"},
+	}}); err != nil {
+		t.Errorf("unexpected error %s", err)
+	}
+	if c != 2 {
+		t.Errorf("expected 2 calls(count from zero) to server got %d", c)
+	}
+}

app/vmalert/notifier/init.go

@@ -0,0 +1,45 @@
+package notifier
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
+)
+
+var (
+	addrs             = flagutil.NewArray("notifier.url", "Prometheus alertmanager URL. Required parameter. e.g. http://127.0.0.1:9093")
+	basicAuthUsername = flagutil.NewArray("notifier.basicAuth.username", "Optional basic auth username for -notifier.url")
+	basicAuthPassword = flagutil.NewArray("notifier.basicAuth.password", "Optional basic auth password for -notifier.url")
+
+	tlsInsecureSkipVerify = flagutil.NewArrayBool("notifier.tlsInsecureSkipVerify", "Whether to skip tls verification when connecting to -notifier.url")
+	tlsCertFile           = flagutil.NewArray("notifier.tlsCertFile", "Optional path to client-side TLS certificate file to use when connecting to -notifier.url")
+	tlsKeyFile            = flagutil.NewArray("notifier.tlsKeyFile", "Optional path to client-side TLS certificate key to use when connecting to -notifier.url")
+	tlsCAFile             = flagutil.NewArray("notifier.tlsCAFile", "Optional path to TLS CA file to use for verifying connections to -notifier.url. "+
+		"By default system CA is used")
+	tlsServerName = flagutil.NewArray("notifier.tlsServerName", "Optional TLS server name to use for connections to -notifier.url. "+
+		"By default the server name from -notifier.url is used")
+)
+
+// Init creates a Notifier object based on provided flags.
+func Init(gen AlertURLGenerator) ([]Notifier, error) {
+	if len(*addrs) == 0 {
+		return nil, fmt.Errorf("at least one `-notifier.url` must be set")
+	}
+
+	var notifiers []Notifier
+	for i, addr := range *addrs {
+		cert, key := tlsCertFile.GetOptionalArg(i), tlsKeyFile.GetOptionalArg(i)
+		ca, serverName := tlsCAFile.GetOptionalArg(i), tlsServerName.GetOptionalArg(i)
+		tr, err := utils.Transport(addr, cert, key, ca, serverName, tlsInsecureSkipVerify.GetOptionalArg(i))
+		if err != nil {
+			return nil, fmt.Errorf("failed to create transport: %w", err)
+		}
+		user, pass := basicAuthUsername.GetOptionalArg(i), basicAuthPassword.GetOptionalArg(i)
+		am := NewAlertManager(addr, user, pass, gen, &http.Client{Transport: tr})
+		notifiers = append(notifiers, am)
+	}
+
+	return notifiers, nil
+}

app/vmalert/notifier/notifier.go

@@ -0,0 +1,13 @@
+package notifier
+
+import "context"
+
+// Notifier is a common interface for alert manager provider
+type Notifier interface {
+	// Send sends the given list of alerts.
+	// Returns an error if fails to send the alerts.
+	// Must unblock if the given ctx is cancelled.
+	Send(ctx context.Context, alerts []Alert) error
+	// Addr returns address where alerts are sent.
+	Addr() string
+}

app/vmalert/notifier/package_test.go

@@ -0,0 +1,13 @@
+package notifier
+
+import (
+	"net/url"
+	"os"
+	"testing"
+)
+
+func TestMain(m *testing.M) {
+	u, _ := url.Parse("https://victoriametrics.com/path")
+	InitTemplateFunc(u)
+	os.Exit(m.Run())
+}

app/vmalert/notifier/template_func.go

@@ -0,0 +1,327 @@
+// Copyright 2013 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package notifier
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"net/url"
+	"regexp"
+	"strings"
+	"time"
+
+	htmlTpl "html/template"
+	textTpl "text/template"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+)
+
+// metric is private copy of datasource.Metric,
+// it is used for templating annotations,
+// Labels as map simplifies templates evaluation.
+type metric struct {
+	Labels    map[string]string
+	Timestamp int64
+	Value     float64
+}
+
+// datasourceMetricsToTemplateMetrics converts Metrics from datasource package to private copy for templating.
+func datasourceMetricsToTemplateMetrics(ms []datasource.Metric) []metric {
+	mss := make([]metric, 0, len(ms))
+	for _, m := range ms {
+		labelsMap := make(map[string]string, len(m.Labels))
+		for _, labelValue := range m.Labels {
+			labelsMap[labelValue.Name] = labelValue.Value
+		}
+		mss = append(mss, metric{
+			Labels:    labelsMap,
+			Timestamp: m.Timestamps[0],
+			Value:     m.Values[0]})
+	}
+	return mss
+}
+
+// QueryFn is used to wrap a call to datasource into simple-to-use function
+// for templating functions.
+type QueryFn func(query string) ([]datasource.Metric, error)
+
+var tmplFunc textTpl.FuncMap
+
+// InitTemplateFunc initiates template helper functions
+func InitTemplateFunc(externalURL *url.URL) {
+	tmplFunc = textTpl.FuncMap{
+		/* Strings */
+
+		// reReplaceAll ReplaceAllString returns a copy of src, replacing matches of the Regexp with
+		// the replacement string repl. Inside repl, $ signs are interpreted as in Expand,
+		// so for instance $1 represents the text of the first submatch.
+		// alias for https://golang.org/pkg/regexp/#Regexp.ReplaceAllString
+		"reReplaceAll": func(pattern, repl, text string) string {
+			re := regexp.MustCompile(pattern)
+			return re.ReplaceAllString(text, repl)
+		},
+
+		// match reports whether the string s
+		// contains any match of the regular expression pattern.
+		// alias for https://golang.org/pkg/regexp/#MatchString
+		"match": regexp.MatchString,
+
+		// title returns a copy of the string s with all Unicode letters
+		// that begin words mapped to their Unicode title case.
+		// alias for https://golang.org/pkg/strings/#Title
+		"title": strings.Title,
+
+		// toUpper returns s with all Unicode letters mapped to their upper case.
+		// alias for https://golang.org/pkg/strings/#ToUpper
+		"toUpper": strings.ToUpper,
+
+		// toLower returns s with all Unicode letters mapped to their lower case.
+		// alias for https://golang.org/pkg/strings/#ToLower
+		"toLower": strings.ToLower,
+
+		/* Numbers */
+
+		// humanize converts given number to a human readable format
+		// by adding metric prefixes https://en.wikipedia.org/wiki/Metric_prefix
+		"humanize": func(v float64) string {
+			if v == 0 || math.IsNaN(v) || math.IsInf(v, 0) {
+				return fmt.Sprintf("%.4g", v)
+			}
+			if math.Abs(v) >= 1 {
+				prefix := ""
+				for _, p := range []string{"k", "M", "G", "T", "P", "E", "Z", "Y"} {
+					if math.Abs(v) < 1000 {
+						break
+					}
+					prefix = p
+					v /= 1000
+				}
+				return fmt.Sprintf("%.4g%s", v, prefix)
+			}
+			prefix := ""
+			for _, p := range []string{"m", "u", "n", "p", "f", "a", "z", "y"} {
+				if math.Abs(v) >= 1 {
+					break
+				}
+				prefix = p
+				v *= 1000
+			}
+			return fmt.Sprintf("%.4g%s", v, prefix)
+		},
+
+		// humanize1024 converts given number to a human readable format with 1024 as base
+		"humanize1024": func(v float64) string {
+			if math.Abs(v) <= 1 || math.IsNaN(v) || math.IsInf(v, 0) {
+				return fmt.Sprintf("%.4g", v)
+			}
+			prefix := ""
+			for _, p := range []string{"ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi", "Yi"} {
+				if math.Abs(v) < 1024 {
+					break
+				}
+				prefix = p
+				v /= 1024
+			}
+			return fmt.Sprintf("%.4g%s", v, prefix)
+		},
+
+		// humanizeDuration converts given seconds to a human readable duration
+		"humanizeDuration": func(v float64) string {
+			if math.IsNaN(v) || math.IsInf(v, 0) {
+				return fmt.Sprintf("%.4g", v)
+			}
+			if v == 0 {
+				return fmt.Sprintf("%.4gs", v)
+			}
+			if math.Abs(v) >= 1 {
+				sign := ""
+				if v < 0 {
+					sign = "-"
+					v = -v
+				}
+				seconds := int64(v) % 60
+				minutes := (int64(v) / 60) % 60
+				hours := (int64(v) / 60 / 60) % 24
+				days := int64(v) / 60 / 60 / 24
+				// For days to minutes, we display seconds as an integer.
+				if days != 0 {
+					return fmt.Sprintf("%s%dd %dh %dm %ds", sign, days, hours, minutes, seconds)
+				}
+				if hours != 0 {
+					return fmt.Sprintf("%s%dh %dm %ds", sign, hours, minutes, seconds)
+				}
+				if minutes != 0 {
+					return fmt.Sprintf("%s%dm %ds", sign, minutes, seconds)
+				}
+				// For seconds, we display 4 significant digits.
+				return fmt.Sprintf("%s%.4gs", sign, v)
+			}
+			prefix := ""
+			for _, p := range []string{"m", "u", "n", "p", "f", "a", "z", "y"} {
+				if math.Abs(v) >= 1 {
+					break
+				}
+				prefix = p
+				v *= 1000
+			}
+			return fmt.Sprintf("%.4g%ss", v, prefix)
+		},
+
+		// humanizePercentage converts given ratio value to a fraction of 100
+		"humanizePercentage": func(v float64) string {
+			return fmt.Sprintf("%.4g%%", v*100)
+		},
+
+		// humanizeTimestamp converts given timestamp to a human readable time equivalent
+		"humanizeTimestamp": func(v float64) string {
+			if math.IsNaN(v) || math.IsInf(v, 0) {
+				return fmt.Sprintf("%.4g", v)
+			}
+			t := TimeFromUnixNano(int64(v * 1e9)).Time().UTC()
+			return fmt.Sprint(t)
+		},
+
+		/* URLs */
+
+		// externalURL returns value of `external.url` flag
+		"externalURL": func() string {
+			return externalURL.String()
+		},
+
+		// pathPrefix returns a Path segment from the URL value in `external.url` flag
+		"pathPrefix": func() string {
+			return externalURL.Path
+		},
+
+		// pathEscape escapes the string so it can be safely placed inside a URL path segment,
+		// replacing special characters (including /) with %XX sequences as needed.
+		// alias for https://golang.org/pkg/net/url/#PathEscape
+		"pathEscape": func(u string) string {
+			return url.PathEscape(u)
+		},
+
+		// queryEscape escapes the string so it can be safely placed
+		// inside a URL query.
+		// alias for https://golang.org/pkg/net/url/#QueryEscape
+		"queryEscape": func(q string) string {
+			return url.QueryEscape(q)
+		},
+
+		// crlfEscape replaces new line chars to skip URL encoding.
+		// see https://github.com/VictoriaMetrics/VictoriaMetrics/issues/890
+		"crlfEscape": func(q string) string {
+			q = strings.Replace(q, "\n", `\n`, -1)
+			return strings.Replace(q, "\r", `\r`, -1)
+		},
+
+		// quotesEscape escapes quote char
+		"quotesEscape": func(q string) string {
+			return strings.Replace(q, `"`, `\"`, -1)
+		},
+
+		// query executes the MetricsQL/PromQL query against
+		// configured `datasource.url` address.
+		// For example, {{ query "foo" | first | value }} will
+		// execute "/api/v1/query?query=foo" request and will return
+		// the first value in response.
+		"query": func(q string) ([]metric, error) {
+			// query function supposed to be substituted at funcsWithQuery().
+			// it is present here only for validation purposes, when there is no
+			// provided datasource.
+			//
+			// return non-empty slice to pass validation with chained functions in template
+			// see issue #989 for details
+			return []metric{{}}, nil
+		},
+
+		// first returns the first by order element from the given metrics list.
+		// usually used alongside with `query` template function.
+		"first": func(metrics []metric) (metric, error) {
+			if len(metrics) > 0 {
+				return metrics[0], nil
+			}
+			return metric{}, errors.New("first() called on vector with no elements")
+		},
+
+		// label returns the value of the given label name for the given metric.
+		// usually used alongside with `query` template function.
+		"label": func(label string, m metric) string {
+			return m.Labels[label]
+		},
+
+		// value returns the value of the given metric.
+		// usually used alongside with `query` template function.
+		"value": func(m metric) float64 {
+			return m.Value
+		},
+
+		/* Helpers */
+
+		// Converts a list of objects to a map with keys arg0, arg1 etc.
+		// This is intended to allow multiple arguments to be passed to templates.
+		"args": func(args ...interface{}) map[string]interface{} {
+			result := make(map[string]interface{})
+			for i, a := range args {
+				result[fmt.Sprintf("arg%d", i)] = a
+			}
+			return result
+		},
+
+		// safeHtml marks string as HTML not requiring auto-escaping.
+		"safeHtml": func(text string) htmlTpl.HTML {
+			return htmlTpl.HTML(text)
+		},
+	}
+}
+
+func funcsWithQuery(query QueryFn) textTpl.FuncMap {
+	fm := make(textTpl.FuncMap)
+	for k, fn := range tmplFunc {
+		fm[k] = fn
+	}
+	fm["query"] = func(q string) ([]metric, error) {
+		result, err := query(q)
+		if err != nil {
+			return nil, err
+		}
+		return datasourceMetricsToTemplateMetrics(result), nil
+	}
+	return fm
+}
+
+// Time is the number of milliseconds since the epoch
+// (1970-01-01 00:00 UTC) excluding leap seconds.
+type Time int64
+
+// TimeFromUnixNano returns the Time equivalent to the Unix Time
+// t provided in nanoseconds.
+func TimeFromUnixNano(t int64) Time {
+	return Time(t / nanosPerTick)
+}
+
+// The number of nanoseconds per minimum tick.
+const nanosPerTick = int64(minimumTick / time.Nanosecond)
+
+// MinimumTick is the minimum supported time resolution. This has to be
+// at least time.Second in order for the code below to work.
+const minimumTick = time.Millisecond
+
+// second is the Time duration equivalent to one second.
+const second = int64(time.Second / minimumTick)
+
+// Time returns the time.Time representation of t.
+func (t Time) Time() time.Time {
+	return time.Unix(int64(t)/second, (int64(t)%second)*nanosPerTick)
+}

app/vmalert/recording.go

@@ -0,0 +1,215 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+// RecordingRule is a Rule that supposed
+// to evaluate configured Expression and
+// return TimeSeries as result.
+type RecordingRule struct {
+	Type    datasource.Type
+	RuleID  uint64
+	Name    string
+	Expr    string
+	Labels  map[string]string
+	GroupID uint64
+
+	q datasource.Querier
+
+	// guard status fields
+	mu sync.RWMutex
+	// stores last moment of time Exec was called
+	lastExecTime time.Time
+	// stores last error that happened in Exec func
+	// resets on every successful Exec
+	// may be used as Health state
+	lastExecError error
+	// stores the number of samples returned during
+	// the last evaluation
+	lastExecSamples int
+
+	metrics *recordingRuleMetrics
+}
+
+type recordingRuleMetrics struct {
+	errors  *gauge
+	samples *gauge
+}
+
+// String implements Stringer interface
+func (rr *RecordingRule) String() string {
+	return rr.Name
+}
+
+// ID returns unique Rule ID
+// within the parent Group.
+func (rr *RecordingRule) ID() uint64 {
+	return rr.RuleID
+}
+
+func newRecordingRule(qb datasource.QuerierBuilder, group *Group, cfg config.Rule) *RecordingRule {
+	rr := &RecordingRule{
+		Type:    cfg.Type,
+		RuleID:  cfg.ID,
+		Name:    cfg.Record,
+		Expr:    cfg.Expr,
+		Labels:  cfg.Labels,
+		GroupID: group.ID(),
+		metrics: &recordingRuleMetrics{},
+		q: qb.BuildWithParams(datasource.QuerierParams{
+			DataSourceType:     &cfg.Type,
+			EvaluationInterval: group.Interval,
+			ExtraLabels:        group.ExtraFilterLabels,
+		}),
+	}
+
+	labels := fmt.Sprintf(`recording=%q, group=%q, id="%d"`, rr.Name, group.Name, rr.ID())
+	rr.metrics.errors = getOrCreateGauge(fmt.Sprintf(`vmalert_recording_rules_error{%s}`, labels),
+		func() float64 {
+			rr.mu.RLock()
+			defer rr.mu.RUnlock()
+			if rr.lastExecError == nil {
+				return 0
+			}
+			return 1
+		})
+	rr.metrics.samples = getOrCreateGauge(fmt.Sprintf(`vmalert_recording_rules_last_evaluation_samples{%s}`, labels),
+		func() float64 {
+			rr.mu.RLock()
+			defer rr.mu.RUnlock()
+			return float64(rr.lastExecSamples)
+		})
+	return rr
+}
+
+// Close unregisters rule metrics
+func (rr *RecordingRule) Close() {
+	metrics.UnregisterMetric(rr.metrics.errors.name)
+	metrics.UnregisterMetric(rr.metrics.samples.name)
+}
+
+// ExecRange executes recording rule on the given time range similarly to Exec.
+// It doesn't update internal states of the Rule and meant to be used just
+// to get time series for backfilling.
+func (rr *RecordingRule) ExecRange(ctx context.Context, start, end time.Time) ([]prompbmarshal.TimeSeries, error) {
+	series, err := rr.q.QueryRange(ctx, rr.Expr, start, end)
+	if err != nil {
+		return nil, err
+	}
+	duplicates := make(map[string]struct{}, len(series))
+	var tss []prompbmarshal.TimeSeries
+	for _, s := range series {
+		ts := rr.toTimeSeries(s)
+		key := stringifyLabels(ts)
+		if _, ok := duplicates[key]; ok {
+			return nil, fmt.Errorf("original metric %v; resulting labels %q: %w", s.Labels, key, errDuplicate)
+		}
+		duplicates[key] = struct{}{}
+		tss = append(tss, ts)
+	}
+	return tss, nil
+}
+
+// Exec executes RecordingRule expression via the given Querier.
+func (rr *RecordingRule) Exec(ctx context.Context) ([]prompbmarshal.TimeSeries, error) {
+	qMetrics, err := rr.q.Query(ctx, rr.Expr)
+	rr.mu.Lock()
+	defer rr.mu.Unlock()
+
+	rr.lastExecTime = time.Now()
+	rr.lastExecError = err
+	rr.lastExecSamples = len(qMetrics)
+	if err != nil {
+		return nil, fmt.Errorf("failed to execute query %q: %w", rr.Expr, err)
+	}
+
+	duplicates := make(map[string]struct{}, len(qMetrics))
+	var tss []prompbmarshal.TimeSeries
+	for _, r := range qMetrics {
+		ts := rr.toTimeSeries(r)
+		key := stringifyLabels(ts)
+		if _, ok := duplicates[key]; ok {
+			rr.lastExecError = errDuplicate
+			return nil, fmt.Errorf("original metric %v; resulting labels %q: %w", r, key, errDuplicate)
+		}
+		duplicates[key] = struct{}{}
+		tss = append(tss, ts)
+	}
+	return tss, nil
+}
+
+func stringifyLabels(ts prompbmarshal.TimeSeries) string {
+	labels := ts.Labels
+	if len(labels) > 1 {
+		sort.Slice(labels, func(i, j int) bool {
+			return labels[i].Name < labels[j].Name
+		})
+	}
+	b := strings.Builder{}
+	for i, l := range labels {
+		b.WriteString(l.Name)
+		b.WriteString("=")
+		b.WriteString(l.Value)
+		if i != len(labels)-1 {
+			b.WriteString(",")
+		}
+	}
+	return b.String()
+}
+
+func (rr *RecordingRule) toTimeSeries(m datasource.Metric) prompbmarshal.TimeSeries {
+	labels := make(map[string]string)
+	for _, l := range m.Labels {
+		labels[l.Name] = l.Value
+	}
+	labels["__name__"] = rr.Name
+	// override existing labels with configured ones
+	for k, v := range rr.Labels {
+		labels[k] = v
+	}
+	return newTimeSeries(m.Values, m.Timestamps, labels)
+}
+
+// UpdateWith copies all significant fields.
+func (rr *RecordingRule) UpdateWith(r Rule) error {
+	nr, ok := r.(*RecordingRule)
+	if !ok {
+		return fmt.Errorf("BUG: attempt to update recroding rule with wrong type %#v", r)
+	}
+	rr.Expr = nr.Expr
+	rr.Labels = nr.Labels
+	rr.q = nr.q
+	return nil
+}
+
+// RuleAPI returns Rule representation in form
+// of APIRecordingRule
+func (rr *RecordingRule) RuleAPI() APIRecordingRule {
+	var lastErr string
+	if rr.lastExecError != nil {
+		lastErr = rr.lastExecError.Error()
+	}
+	return APIRecordingRule{
+		// encode as strings to avoid rounding
+		ID:          fmt.Sprintf("%d", rr.ID()),
+		GroupID:     fmt.Sprintf("%d", rr.GroupID),
+		Name:        rr.Name,
+		Type:        rr.Type.String(),
+		Expression:  rr.Expr,
+		LastError:   lastErr,
+		LastSamples: rr.lastExecSamples,
+		LastExec:    rr.lastExecTime,
+		Labels:      rr.Labels,
+	}
+}

app/vmalert/recording_test.go

@@ -0,0 +1,203 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+)
+
+func TestRecoridngRule_Exec(t *testing.T) {
+	timestamp := time.Now()
+	testCases := []struct {
+		rule    *RecordingRule
+		metrics []datasource.Metric
+		expTS   []prompbmarshal.TimeSeries
+	}{
+		{
+			&RecordingRule{Name: "foo"},
+			[]datasource.Metric{metricWithValueAndLabels(t, 10,
+				"__name__", "bar",
+			)},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries([]float64{10}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__": "foo",
+				}),
+			},
+		},
+		{
+			&RecordingRule{Name: "foobarbaz"},
+			[]datasource.Metric{
+				metricWithValueAndLabels(t, 1, "__name__", "foo", "job", "foo"),
+				metricWithValueAndLabels(t, 2, "__name__", "bar", "job", "bar"),
+				metricWithValueAndLabels(t, 3, "__name__", "baz", "job", "baz"),
+			},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries([]float64{1}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__": "foobarbaz",
+					"job":      "foo",
+				}),
+				newTimeSeries([]float64{2}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__": "foobarbaz",
+					"job":      "bar",
+				}),
+				newTimeSeries([]float64{3}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__": "foobarbaz",
+					"job":      "baz",
+				}),
+			},
+		},
+		{
+			&RecordingRule{Name: "job:foo", Labels: map[string]string{
+				"source": "test",
+			}},
+			[]datasource.Metric{
+				metricWithValueAndLabels(t, 2, "__name__", "foo", "job", "foo"),
+				metricWithValueAndLabels(t, 1, "__name__", "bar", "job", "bar")},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries([]float64{2}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__": "job:foo",
+					"job":      "foo",
+					"source":   "test",
+				}),
+				newTimeSeries([]float64{1}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__": "job:foo",
+					"job":      "bar",
+					"source":   "test",
+				}),
+			},
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.rule.Name, func(t *testing.T) {
+			fq := &fakeQuerier{}
+			fq.add(tc.metrics...)
+			tc.rule.q = fq
+			tss, err := tc.rule.Exec(context.TODO())
+			if err != nil {
+				t.Fatalf("unexpected Exec err: %s", err)
+			}
+			if err := compareTimeSeries(t, tc.expTS, tss); err != nil {
+				t.Fatalf("timeseries missmatch: %s", err)
+			}
+		})
+	}
+}
+
+func TestRecoridngRule_ExecRange(t *testing.T) {
+	timestamp := time.Now()
+	testCases := []struct {
+		rule    *RecordingRule
+		metrics []datasource.Metric
+		expTS   []prompbmarshal.TimeSeries
+	}{
+		{
+			&RecordingRule{Name: "foo"},
+			[]datasource.Metric{metricWithValuesAndLabels(t, []float64{10, 20, 30},
+				"__name__", "bar",
+			)},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries([]float64{10, 20, 30},
+					[]int64{timestamp.UnixNano(), timestamp.UnixNano(), timestamp.UnixNano()},
+					map[string]string{
+						"__name__": "foo",
+					}),
+			},
+		},
+		{
+			&RecordingRule{Name: "foobarbaz"},
+			[]datasource.Metric{
+				metricWithValuesAndLabels(t, []float64{1}, "__name__", "foo", "job", "foo"),
+				metricWithValuesAndLabels(t, []float64{2, 3}, "__name__", "bar", "job", "bar"),
+				metricWithValuesAndLabels(t, []float64{4, 5, 6}, "__name__", "baz", "job", "baz"),
+			},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries([]float64{1}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__": "foobarbaz",
+					"job":      "foo",
+				}),
+				newTimeSeries([]float64{2, 3}, []int64{timestamp.UnixNano(), timestamp.UnixNano()}, map[string]string{
+					"__name__": "foobarbaz",
+					"job":      "bar",
+				}),
+				newTimeSeries([]float64{4, 5, 6},
+					[]int64{timestamp.UnixNano(), timestamp.UnixNano(), timestamp.UnixNano()},
+					map[string]string{
+						"__name__": "foobarbaz",
+						"job":      "baz",
+					}),
+			},
+		},
+		{
+			&RecordingRule{Name: "job:foo", Labels: map[string]string{
+				"source": "test",
+			}},
+			[]datasource.Metric{
+				metricWithValueAndLabels(t, 2, "__name__", "foo", "job", "foo"),
+				metricWithValueAndLabels(t, 1, "__name__", "bar", "job", "bar")},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries([]float64{2}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__": "job:foo",
+					"job":      "foo",
+					"source":   "test",
+				}),
+				newTimeSeries([]float64{1}, []int64{timestamp.UnixNano()}, map[string]string{
+					"__name__": "job:foo",
+					"job":      "bar",
+					"source":   "test",
+				}),
+			},
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.rule.Name, func(t *testing.T) {
+			fq := &fakeQuerier{}
+			fq.add(tc.metrics...)
+			tc.rule.q = fq
+			tss, err := tc.rule.ExecRange(context.TODO(), time.Now(), time.Now())
+			if err != nil {
+				t.Fatalf("unexpected Exec err: %s", err)
+			}
+			if err := compareTimeSeries(t, tc.expTS, tss); err != nil {
+				t.Fatalf("timeseries missmatch: %s", err)
+			}
+		})
+	}
+}
+
+func TestRecoridngRule_ExecNegative(t *testing.T) {
+	rr := &RecordingRule{Name: "job:foo", Labels: map[string]string{
+		"job": "test",
+	}}
+
+	fq := &fakeQuerier{}
+	expErr := "connection reset by peer"
+	fq.setErr(errors.New(expErr))
+	rr.q = fq
+	_, err := rr.Exec(context.TODO())
+	if err == nil {
+		t.Fatalf("expected to get err; got nil")
+	}
+	if !strings.Contains(err.Error(), expErr) {
+		t.Fatalf("expected to get err %q; got %q insterad", expErr, err)
+	}
+
+	fq.reset()
+
+	// add metrics which differs only by `job` label
+	// which will be overridden by rule
+	fq.add(metricWithValueAndLabels(t, 1, "__name__", "foo", "job", "foo"))
+	fq.add(metricWithValueAndLabels(t, 2, "__name__", "foo", "job", "bar"))
+
+	_, err = rr.Exec(context.TODO())
+	if err == nil {
+		t.Fatalf("expected to get err; got nil")
+	}
+	if !strings.Contains(err.Error(), errDuplicate.Error()) {
+		t.Fatalf("expected to get err %q; got %q insterad", errDuplicate, err)
+	}
+}

app/vmalert/remoteread/init.go

@@ -0,0 +1,47 @@
+package remoteread
+
+import (
+	"flag"
+	"fmt"
+	"net/http"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+)
+
+var (
+	addr = flag.String("remoteRead.url", "", "Optional URL to VictoriaMetrics or vmselect that will be used to restore alerts "+
+		"state. This configuration makes sense only if `vmalert` was configured with `remoteWrite.url` before and has been successfully persisted its state. "+
+		"E.g. http://127.0.0.1:8428")
+	basicAuthUsername     = flag.String("remoteRead.basicAuth.username", "", "Optional basic auth username for -remoteRead.url")
+	basicAuthPassword     = flag.String("remoteRead.basicAuth.password", "", "Optional basic auth password for -remoteRead.url")
+	basicAuthPasswordFile = flag.String("remoteRead.basicAuth.passwordFile", "", "Optional path to basic auth password to use for -remoteRead.url")
+	bearerToken           = flag.String("remoteRead.bearerToken", "", "Optional bearer auth token to use for -remoteRead.url.")
+	bearerTokenFile       = flag.String("remoteRead.bearerTokenFile", "", "Optional path to bearer token file to use for -remoteRead.url.")
+
+	tlsInsecureSkipVerify = flag.Bool("remoteRead.tlsInsecureSkipVerify", false, "Whether to skip tls verification when connecting to -remoteRead.url")
+	tlsCertFile           = flag.String("remoteRead.tlsCertFile", "", "Optional path to client-side TLS certificate file to use when connecting to -remoteRead.url")
+	tlsKeyFile            = flag.String("remoteRead.tlsKeyFile", "", "Optional path to client-side TLS certificate key to use when connecting to -remoteRead.url")
+	tlsCAFile             = flag.String("remoteRead.tlsCAFile", "", "Optional path to TLS CA file to use for verifying connections to -remoteRead.url. "+
+		"By default system CA is used")
+	tlsServerName = flag.String("remoteRead.tlsServerName", "", "Optional TLS server name to use for connections to -remoteRead.url. "+
+		"By default the server name from -remoteRead.url is used")
+)
+
+// Init creates a Querier from provided flag values.
+// Returns nil if addr flag wasn't set.
+func Init() (datasource.QuerierBuilder, error) {
+	if *addr == "" {
+		return nil, nil
+	}
+	tr, err := utils.Transport(*addr, *tlsCertFile, *tlsKeyFile, *tlsCAFile, *tlsServerName, *tlsInsecureSkipVerify)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create transport: %w", err)
+	}
+	authCfg, err := utils.AuthConfig(*basicAuthUsername, *basicAuthPassword, *basicAuthPasswordFile, *bearerToken, *bearerTokenFile)
+	if err != nil {
+		return nil, fmt.Errorf("failed to configure auth: %w", err)
+	}
+	c := &http.Client{Transport: tr}
+	return datasource.NewVMStorage(*addr, authCfg, 0, 0, false, c), nil
+}

app/vmalert/remotewrite/init.go

@@ -0,0 +1,64 @@
+package remotewrite
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+)
+
+var (
+	addr = flag.String("remoteWrite.url", "", "Optional URL to VictoriaMetrics or vminsert where to persist alerts state "+
+		"and recording rules results in form of timeseries. For example, if -remoteWrite.url=http://127.0.0.1:8428 is specified, "+
+		"then the alerts state will be written to http://127.0.0.1:8428/api/v1/write . See also -remoteWrite.disablePathAppend")
+	basicAuthUsername     = flag.String("remoteWrite.basicAuth.username", "", "Optional basic auth username for -remoteWrite.url")
+	basicAuthPassword     = flag.String("remoteWrite.basicAuth.password", "", "Optional basic auth password for -remoteWrite.url")
+	basicAuthPasswordFile = flag.String("remoteWrite.basicAuth.passwordFile", "", "Optional path to basic auth password to use for -remoteWrite.url")
+	bearerToken           = flag.String("remoteWrite.bearerToken", "", "Optional bearer auth token to use for -remoteWrite.url.")
+	bearerTokenFile       = flag.String("remoteWrite.bearerTokenFile", "", "Optional path to bearer token file to use for -remoteWrite.url.")
+
+	maxQueueSize  = flag.Int("remoteWrite.maxQueueSize", 1e5, "Defines the max number of pending datapoints to remote write endpoint")
+	maxBatchSize  = flag.Int("remoteWrite.maxBatchSize", 1e3, "Defines defines max number of timeseries to be flushed at once")
+	concurrency   = flag.Int("remoteWrite.concurrency", 1, "Defines number of writers for concurrent writing into remote querier")
+	flushInterval = flag.Duration("remoteWrite.flushInterval", 5*time.Second, "Defines interval of flushes to remote write endpoint")
+
+	tlsInsecureSkipVerify = flag.Bool("remoteWrite.tlsInsecureSkipVerify", false, "Whether to skip tls verification when connecting to -remoteWrite.url")
+	tlsCertFile           = flag.String("remoteWrite.tlsCertFile", "", "Optional path to client-side TLS certificate file to use when connecting to -remoteWrite.url")
+	tlsKeyFile            = flag.String("remoteWrite.tlsKeyFile", "", "Optional path to client-side TLS certificate key to use when connecting to -remoteWrite.url")
+	tlsCAFile             = flag.String("remoteWrite.tlsCAFile", "", "Optional path to TLS CA file to use for verifying connections to -remoteWrite.url. "+
+		"By default system CA is used")
+	tlsServerName = flag.String("remoteWrite.tlsServerName", "", "Optional TLS server name to use for connections to -remoteWrite.url. "+
+		"By default the server name from -remoteWrite.url is used")
+	disablePathAppend = flag.Bool("remoteWrite.disablePathAppend", false, "Whether to disable automatic appending of '/api/v1/write' path to the configured -remoteWrite.url.")
+)
+
+// Init creates Client object from given flags.
+// Returns nil if addr flag wasn't set.
+func Init(ctx context.Context) (*Client, error) {
+	if *addr == "" {
+		return nil, nil
+	}
+
+	t, err := utils.Transport(*addr, *tlsCertFile, *tlsKeyFile, *tlsCAFile, *tlsServerName, *tlsInsecureSkipVerify)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create transport: %w", err)
+	}
+
+	authCfg, err := utils.AuthConfig(*basicAuthUsername, *basicAuthPassword, *basicAuthPasswordFile, *bearerToken, *bearerTokenFile)
+	if err != nil {
+		return nil, fmt.Errorf("failed to configure auth: %w", err)
+	}
+
+	return NewClient(ctx, Config{
+		Addr:              *addr,
+		AuthCfg:           authCfg,
+		Concurrency:       *concurrency,
+		MaxQueueSize:      *maxQueueSize,
+		MaxBatchSize:      *maxBatchSize,
+		FlushInterval:     *flushInterval,
+		DisablePathAppend: *disablePathAppend,
+		Transport:         t,
+	})
+}

app/vmalert/remotewrite/remotewrite.go

@@ -0,0 +1,258 @@
+package remotewrite
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"path"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/golang/snappy"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promauth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+// Client is an asynchronous HTTP client for writing
+// timeseries via remote write protocol.
+type Client struct {
+	addr              string
+	c                 *http.Client
+	authCfg           *promauth.Config
+	input             chan prompbmarshal.TimeSeries
+	flushInterval     time.Duration
+	maxBatchSize      int
+	maxQueueSize      int
+	disablePathAppend bool
+
+	wg     sync.WaitGroup
+	doneCh chan struct{}
+}
+
+// Config is config for remote write.
+type Config struct {
+	// Addr of remote storage
+	Addr    string
+	AuthCfg *promauth.Config
+
+	// Concurrency defines number of readers that
+	// concurrently read from the queue and flush data
+	Concurrency int
+	// MaxBatchSize defines max number of timeseries
+	// to be flushed at once
+	MaxBatchSize int
+	// MaxQueueSize defines max length of input queue
+	// populated by Push method.
+	// Push will be rejected once queue is full.
+	MaxQueueSize int
+	// FlushInterval defines time interval for flushing batches
+	FlushInterval time.Duration
+	// WriteTimeout defines timeout for HTTP write request
+	// to remote storage
+	WriteTimeout time.Duration
+	// Transport will be used by the underlying http.Client
+	Transport *http.Transport
+	// DisablePathAppend can be used to not automatically append '/api/v1/write' to the remote write url
+	DisablePathAppend bool
+}
+
+const (
+	defaultConcurrency   = 4
+	defaultMaxBatchSize  = 1e3
+	defaultMaxQueueSize  = 1e5
+	defaultFlushInterval = 5 * time.Second
+	defaultWriteTimeout  = 30 * time.Second
+)
+
+const writePath = "/api/v1/write"
+
+// NewClient returns asynchronous client for
+// writing timeseries via remotewrite protocol.
+func NewClient(ctx context.Context, cfg Config) (*Client, error) {
+	if cfg.Addr == "" {
+		return nil, fmt.Errorf("config.Addr can't be empty")
+	}
+	if cfg.MaxBatchSize == 0 {
+		cfg.MaxBatchSize = defaultMaxBatchSize
+	}
+	if cfg.MaxQueueSize == 0 {
+		cfg.MaxQueueSize = defaultMaxQueueSize
+	}
+	if cfg.FlushInterval == 0 {
+		cfg.FlushInterval = defaultFlushInterval
+	}
+	if cfg.WriteTimeout == 0 {
+		cfg.WriteTimeout = defaultWriteTimeout
+	}
+	if cfg.Transport == nil {
+		cfg.Transport = http.DefaultTransport.(*http.Transport).Clone()
+	}
+	cc := defaultConcurrency
+	if cfg.Concurrency > 0 {
+		cc = cfg.Concurrency
+	}
+	c := &Client{
+		c: &http.Client{
+			Timeout:   cfg.WriteTimeout,
+			Transport: cfg.Transport,
+		},
+		addr:              strings.TrimSuffix(cfg.Addr, "/"),
+		authCfg:           cfg.AuthCfg,
+		flushInterval:     cfg.FlushInterval,
+		maxBatchSize:      cfg.MaxBatchSize,
+		maxQueueSize:      cfg.MaxQueueSize,
+		doneCh:            make(chan struct{}),
+		input:             make(chan prompbmarshal.TimeSeries, cfg.MaxQueueSize),
+		disablePathAppend: cfg.DisablePathAppend,
+	}
+
+	for i := 0; i < cc; i++ {
+		c.run(ctx)
+	}
+	return c, nil
+}
+
+// Push adds timeseries into queue for writing into remote storage.
+// Push returns and error if client is stopped or if queue is full.
+func (c *Client) Push(s prompbmarshal.TimeSeries) error {
+	select {
+	case <-c.doneCh:
+		return fmt.Errorf("client is closed")
+	case c.input <- s:
+		return nil
+	default:
+		return fmt.Errorf("failed to push timeseries - queue is full (%d entries). "+
+			"Queue size is controlled by -remoteWrite.maxQueueSize flag",
+			c.maxQueueSize)
+	}
+}
+
+// Close stops the client and waits for all goroutines
+// to exit.
+func (c *Client) Close() error {
+	if c.doneCh == nil {
+		return fmt.Errorf("client is already closed")
+	}
+	close(c.input)
+	close(c.doneCh)
+	c.wg.Wait()
+	return nil
+}
+
+func (c *Client) run(ctx context.Context) {
+	ticker := time.NewTicker(c.flushInterval)
+	wr := &prompbmarshal.WriteRequest{}
+	shutdown := func() {
+		for ts := range c.input {
+			wr.Timeseries = append(wr.Timeseries, ts)
+		}
+		lastCtx, cancel := context.WithTimeout(context.Background(), defaultWriteTimeout)
+		c.flush(lastCtx, wr)
+		cancel()
+	}
+	c.wg.Add(1)
+	go func() {
+		defer c.wg.Done()
+		defer ticker.Stop()
+		for {
+			select {
+			case <-c.doneCh:
+				shutdown()
+				return
+			case <-ctx.Done():
+				shutdown()
+				return
+			case <-ticker.C:
+				c.flush(ctx, wr)
+			case ts, ok := <-c.input:
+				if !ok {
+					continue
+				}
+				wr.Timeseries = append(wr.Timeseries, ts)
+				if len(wr.Timeseries) >= c.maxBatchSize {
+					c.flush(ctx, wr)
+				}
+			}
+		}
+	}()
+}
+
+var (
+	sentRows            = metrics.NewCounter(`vmalert_remotewrite_sent_rows_total`)
+	sentBytes           = metrics.NewCounter(`vmalert_remotewrite_sent_bytes_total`)
+	droppedRows         = metrics.NewCounter(`vmalert_remotewrite_dropped_rows_total`)
+	droppedBytes        = metrics.NewCounter(`vmalert_remotewrite_dropped_bytes_total`)
+	bufferFlushDuration = metrics.NewHistogram(`vmalert_remotewrite_flush_duration_seconds`)
+)
+
+// flush is a blocking function that marshals WriteRequest and sends
+// it to remote write endpoint. Flush performs limited amount of retries
+// if request fails.
+func (c *Client) flush(ctx context.Context, wr *prompbmarshal.WriteRequest) {
+	if len(wr.Timeseries) < 1 {
+		return
+	}
+	defer prompbmarshal.ResetWriteRequest(wr)
+	defer bufferFlushDuration.UpdateDuration(time.Now())
+
+	data, err := wr.Marshal()
+	if err != nil {
+		logger.Errorf("failed to marshal WriteRequest: %s", err)
+		return
+	}
+
+	const attempts = 5
+	b := snappy.Encode(nil, data)
+	for i := 0; i < attempts; i++ {
+		err := c.send(ctx, b)
+		if err == nil {
+			sentRows.Add(len(wr.Timeseries))
+			sentBytes.Add(len(b))
+			return
+		}
+
+		logger.Errorf("attempt %d to send request failed: %s", i+1, err)
+		// sleeping to avoid remote db hammering
+		time.Sleep(time.Second)
+		continue
+	}
+
+	droppedRows.Add(len(wr.Timeseries))
+	droppedBytes.Add(len(b))
+	logger.Errorf("all %d attempts to send request failed - dropping %d timeseries",
+		attempts, len(wr.Timeseries))
+}
+
+func (c *Client) send(ctx context.Context, data []byte) error {
+	r := bytes.NewReader(data)
+	req, err := http.NewRequest("POST", c.addr, r)
+	if err != nil {
+		return fmt.Errorf("failed to create new HTTP request: %w", err)
+	}
+	if c.authCfg != nil {
+		if auth := c.authCfg.GetAuthHeader(); auth != "" {
+			req.Header.Set("Authorization", auth)
+		}
+	}
+	if !c.disablePathAppend {
+		req.URL.Path = path.Join(req.URL.Path, writePath)
+	}
+	resp, err := c.c.Do(req.WithContext(ctx))
+	if err != nil {
+		return fmt.Errorf("error while sending request to %s: %w; Data len %d(%d)",
+			req.URL, err, len(data), r.Size())
+	}
+	defer func() { _ = resp.Body.Close() }()
+	if resp.StatusCode != http.StatusNoContent && resp.StatusCode != http.StatusOK {
+		body, _ := ioutil.ReadAll(resp.Body)
+		return fmt.Errorf("unexpected response code %d for %s. Response body %q",
+			resp.StatusCode, req.URL, body)
+	}
+	return nil
+}

app/vmalert/remotewrite/remotewrite_test.go

@@ -0,0 +1,102 @@
+package remotewrite
+
+import (
+	"context"
+	"fmt"
+	"io/ioutil"
+	"math/rand"
+	"net/http"
+	"net/http/httptest"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/golang/snappy"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompb"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+)
+
+func TestClient_Push(t *testing.T) {
+	testSrv := newRWServer()
+	cfg := Config{
+		Addr:         testSrv.URL,
+		MaxBatchSize: 100,
+	}
+	client, err := NewClient(context.Background(), cfg)
+	if err != nil {
+		t.Fatalf("failed to create client: %s", err)
+	}
+	const rowsN = 1e4
+	var sent int
+	for i := 0; i < rowsN; i++ {
+		s := prompbmarshal.TimeSeries{
+			Samples: []prompbmarshal.Sample{{
+				Value:     rand.Float64(),
+				Timestamp: time.Now().Unix(),
+			}},
+		}
+		err := client.Push(s)
+		if err == nil {
+			sent++
+		}
+	}
+	if sent == 0 {
+		t.Fatalf("0 series sent")
+	}
+	if err := client.Close(); err != nil {
+		t.Fatalf("failed to close client: %s", err)
+	}
+	got := testSrv.accepted()
+	if got != sent {
+		t.Fatalf("expected to have %d series; got %d", sent, got)
+	}
+}
+
+func newRWServer() *rwServer {
+	rw := &rwServer{}
+	rw.Server = httptest.NewServer(http.HandlerFunc(rw.handler))
+	return rw
+}
+
+type rwServer struct {
+	// WARN: ordering of fields is important for alignment!
+	// see https://golang.org/pkg/sync/atomic/#pkg-note-BUG
+	acceptedRows uint64
+	*httptest.Server
+}
+
+func (rw *rwServer) accepted() int {
+	return int(atomic.LoadUint64(&rw.acceptedRows))
+}
+
+func (rw *rwServer) err(w http.ResponseWriter, err error) {
+	w.WriteHeader(http.StatusBadRequest)
+	w.Write([]byte(err.Error()))
+}
+
+func (rw *rwServer) handler(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		rw.err(w, fmt.Errorf("bad method %q", r.Method))
+		return
+	}
+	data, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		rw.err(w, fmt.Errorf("body read err: %w", err))
+		return
+	}
+	defer func() { _ = r.Body.Close() }()
+
+	b, err := snappy.Decode(nil, data)
+	if err != nil {
+		rw.err(w, fmt.Errorf("decode err: %w", err))
+		return
+	}
+	wr := &prompb.WriteRequest{}
+	if err := wr.Unmarshal(b); err != nil {
+		rw.err(w, fmt.Errorf("unmarhsal err: %w", err))
+		return
+	}
+	atomic.AddUint64(&rw.acceptedRows, uint64(len(wr.Timeseries)))
+	w.WriteHeader(http.StatusNoContent)
+}

app/vmalert/replay.go

@@ -0,0 +1,160 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/cheggaaa/pb/v3"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+)
+
+var (
+	replayFrom = flag.String("replay.timeFrom", "",
+		"The time filter in RFC3339 format to select time series with timestamp equal or higher than provided value. E.g. '2020-01-01T20:07:00Z'")
+	replayTo = flag.String("replay.timeTo", "",
+		"The time filter in RFC3339 format to select timeseries with timestamp equal or lower than provided value. E.g. '2020-01-01T20:07:00Z'")
+	replayRulesDelay = flag.Duration("replay.rulesDelay", time.Second,
+		"Delay between rules evaluation within the group. Could be important if there are chained rules inside of the group"+
+			"and processing need to wait for previous rule results to be persisted by remote storage before evaluating the next rule."+
+			"Keep it equal or bigger than -remoteWrite.flushInterval.")
+	replayMaxDatapoints = flag.Int("replay.maxDatapointsPerQuery", 1e3,
+		"Max number of data points expected in one request. The higher the value, the less requests will be made during replay.")
+	replayRuleRetryAttempts = flag.Int("replay.ruleRetryAttempts", 5,
+		"Defines how many retries to make before giving up on rule if request for it returns an error.")
+)
+
+func replay(groupsCfg []config.Group, qb datasource.QuerierBuilder, rw *remotewrite.Client) error {
+	if *replayMaxDatapoints < 1 {
+		return fmt.Errorf("replay.maxDatapointsPerQuery can't be lower than 1")
+	}
+	tFrom, err := time.Parse(time.RFC3339, *replayFrom)
+	if err != nil {
+		return fmt.Errorf("failed to parse %q: %s", *replayFrom, err)
+	}
+	tTo, err := time.Parse(time.RFC3339, *replayTo)
+	if err != nil {
+		return fmt.Errorf("failed to parse %q: %s", *replayTo, err)
+	}
+	if !tTo.After(tFrom) {
+		return fmt.Errorf("replay.timeTo must be bigger than replay.timeFrom")
+	}
+	labels := make(map[string]string)
+	for _, s := range *externalLabels {
+		if len(s) == 0 {
+			continue
+		}
+		n := strings.IndexByte(s, '=')
+		if n < 0 {
+			return fmt.Errorf("missing '=' in `-label`. It must contain label in the form `name=value`; got %q", s)
+		}
+		labels[s[:n]] = s[n+1:]
+	}
+
+	fmt.Printf("Replay mode:"+
+		"\nfrom: \t%v "+
+		"\nto: \t%v "+
+		"\nmax data points per request: %d\n",
+		tFrom, tTo, *replayMaxDatapoints)
+
+	var total int
+	for _, cfg := range groupsCfg {
+		ng := newGroup(cfg, qb, *evaluationInterval, labels)
+		total += ng.replay(tFrom, tTo, rw)
+	}
+	logger.Infof("replay finished! Imported %d samples", total)
+	if rw != nil {
+		return rw.Close()
+	}
+	return nil
+}
+
+func (g *Group) replay(start, end time.Time, rw *remotewrite.Client) int {
+	var total int
+	step := g.Interval * time.Duration(*replayMaxDatapoints)
+	ri := rangeIterator{start: start, end: end, step: step}
+	iterations := int(end.Sub(start)/step) + 1
+	fmt.Printf("\nGroup %q"+
+		"\ninterval: \t%v"+
+		"\nrequests to make: \t%d"+
+		"\nmax range per request: \t%v\n",
+		g.Name, g.Interval, iterations, step)
+	for _, rule := range g.Rules {
+		fmt.Printf("> Rule %q (ID: %d)\n", rule, rule.ID())
+		bar := pb.StartNew(iterations)
+		ri.reset()
+		for ri.next() {
+			n, err := replayRule(rule, ri.s, ri.e, rw)
+			if err != nil {
+				logger.Fatalf("rule %q: %s", rule, err)
+			}
+			total += n
+			bar.Increment()
+		}
+		bar.Finish()
+		// sleep to let remote storage to flush data on-disk
+		// so chained rules could be calculated correctly
+		time.Sleep(*replayRulesDelay)
+	}
+	return total
+}
+
+func replayRule(rule Rule, start, end time.Time, rw *remotewrite.Client) (int, error) {
+	var err error
+	var tss []prompbmarshal.TimeSeries
+	for i := 0; i < *replayRuleRetryAttempts; i++ {
+		tss, err = rule.ExecRange(context.Background(), start, end)
+		if err == nil {
+			break
+		}
+		logger.Errorf("attempt %d to execute rule %q failed: %s", i+1, rule, err)
+		time.Sleep(time.Second)
+	}
+	if err != nil { // means all attempts failed
+		return 0, err
+	}
+	if len(tss) < 1 {
+		return 0, nil
+	}
+	var n int
+	for _, ts := range tss {
+		if err := rw.Push(ts); err != nil {
+			return n, fmt.Errorf("remote write failure: %s", err)
+		}
+		n += len(ts.Samples)
+	}
+	return n, nil
+}
+
+type rangeIterator struct {
+	step       time.Duration
+	start, end time.Time
+
+	iter int
+	s, e time.Time
+}
+
+func (ri *rangeIterator) reset() {
+	ri.iter = 0
+	ri.s, ri.e = time.Time{}, time.Time{}
+}
+
+func (ri *rangeIterator) next() bool {
+	ri.s = ri.start.Add(ri.step * time.Duration(ri.iter))
+	if !ri.end.After(ri.s) {
+		return false
+	}
+	ri.e = ri.s.Add(ri.step)
+	if ri.e.After(ri.end) {
+		ri.e = ri.end
+	}
+	ri.iter++
+	return true
+}

app/vmalert/replay_test.go

@@ -0,0 +1,250 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+)
+
+type fakeReplayQuerier struct {
+	fakeQuerier
+	registry map[string]map[string]struct{}
+}
+
+func (fr *fakeReplayQuerier) BuildWithParams(_ datasource.QuerierParams) datasource.Querier {
+	return fr
+}
+
+func (fr *fakeReplayQuerier) QueryRange(_ context.Context, q string, from, to time.Time) ([]datasource.Metric, error) {
+	key := fmt.Sprintf("%s+%s", from.Format("15:04:05"), to.Format("15:04:05"))
+	dps, ok := fr.registry[q]
+	if !ok {
+		return nil, fmt.Errorf("unexpected query received: %q", q)
+	}
+	_, ok = dps[key]
+	if !ok {
+		return nil, fmt.Errorf("unexpected time range received: %q", key)
+	}
+	delete(dps, key)
+	if len(fr.registry[q]) < 1 {
+		delete(fr.registry, q)
+	}
+	return nil, nil
+}
+
+func TestReplay(t *testing.T) {
+	testCases := []struct {
+		name     string
+		from, to string
+		maxDP    int
+		cfg      []config.Group
+		qb       *fakeReplayQuerier
+	}{
+		{
+			name:  "one rule + one response",
+			from:  "2021-01-01T12:00:00.000Z",
+			to:    "2021-01-01T12:02:00.000Z",
+			maxDP: 10,
+			cfg: []config.Group{
+				{Rules: []config.Rule{{Record: "foo", Expr: "sum(up)"}}},
+			},
+			qb: &fakeReplayQuerier{
+				registry: map[string]map[string]struct{}{
+					"sum(up)": {"12:00:00+12:02:00": {}},
+				},
+			},
+		},
+		{
+			name:  "one rule + multiple responses",
+			from:  "2021-01-01T12:00:00.000Z",
+			to:    "2021-01-01T12:02:30.000Z",
+			maxDP: 1,
+			cfg: []config.Group{
+				{Rules: []config.Rule{{Record: "foo", Expr: "sum(up)"}}},
+			},
+			qb: &fakeReplayQuerier{
+				registry: map[string]map[string]struct{}{
+					"sum(up)": {
+						"12:00:00+12:01:00": {},
+						"12:01:00+12:02:00": {},
+						"12:02:00+12:02:30": {},
+					},
+				},
+			},
+		},
+		{
+			name:  "datapoints per step",
+			from:  "2021-01-01T12:00:00.000Z",
+			to:    "2021-01-01T15:02:30.000Z",
+			maxDP: 60,
+			cfg: []config.Group{
+				{Interval: utils.NewPromDuration(time.Minute), Rules: []config.Rule{{Record: "foo", Expr: "sum(up)"}}},
+			},
+			qb: &fakeReplayQuerier{
+				registry: map[string]map[string]struct{}{
+					"sum(up)": {
+						"12:00:00+13:00:00": {},
+						"13:00:00+14:00:00": {},
+						"14:00:00+15:00:00": {},
+						"15:00:00+15:02:30": {},
+					},
+				},
+			},
+		},
+		{
+			name:  "multiple recording rules + multiple responses",
+			from:  "2021-01-01T12:00:00.000Z",
+			to:    "2021-01-01T12:02:30.000Z",
+			maxDP: 1,
+			cfg: []config.Group{
+				{Rules: []config.Rule{{Record: "foo", Expr: "sum(up)"}}},
+				{Rules: []config.Rule{{Record: "bar", Expr: "max(up)"}}},
+			},
+			qb: &fakeReplayQuerier{
+				registry: map[string]map[string]struct{}{
+					"sum(up)": {
+						"12:00:00+12:01:00": {},
+						"12:01:00+12:02:00": {},
+						"12:02:00+12:02:30": {},
+					},
+					"max(up)": {
+						"12:00:00+12:01:00": {},
+						"12:01:00+12:02:00": {},
+						"12:02:00+12:02:30": {},
+					},
+				},
+			},
+		},
+		{
+			name:  "multiple alerting rules + multiple responses",
+			from:  "2021-01-01T12:00:00.000Z",
+			to:    "2021-01-01T12:02:30.000Z",
+			maxDP: 1,
+			cfg: []config.Group{
+				{Rules: []config.Rule{{Alert: "foo", Expr: "sum(up) > 1"}}},
+				{Rules: []config.Rule{{Alert: "bar", Expr: "max(up) < 1"}}},
+			},
+			qb: &fakeReplayQuerier{
+				registry: map[string]map[string]struct{}{
+					"sum(up) > 1": {
+						"12:00:00+12:01:00": {},
+						"12:01:00+12:02:00": {},
+						"12:02:00+12:02:30": {},
+					},
+					"max(up) < 1": {
+						"12:00:00+12:01:00": {},
+						"12:01:00+12:02:00": {},
+						"12:02:00+12:02:30": {},
+					},
+				},
+			},
+		},
+	}
+
+	from, to, maxDP := *replayFrom, *replayTo, *replayMaxDatapoints
+	retries, delay := *replayRuleRetryAttempts, *replayRulesDelay
+	defer func() {
+		*replayFrom, *replayTo = from, to
+		*replayMaxDatapoints, *replayRuleRetryAttempts = maxDP, retries
+		*replayRulesDelay = delay
+	}()
+
+	*replayRuleRetryAttempts = 1
+	*replayRulesDelay = time.Millisecond
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			*replayFrom = tc.from
+			*replayTo = tc.to
+			*replayMaxDatapoints = tc.maxDP
+			if err := replay(tc.cfg, tc.qb, nil); err != nil {
+				t.Fatalf("replay failed: %s", err)
+			}
+			if len(tc.qb.registry) > 0 {
+				t.Fatalf("not all requests were sent: %#v", tc.qb.registry)
+			}
+		})
+	}
+}
+
+func TestRangeIterator(t *testing.T) {
+	testCases := []struct {
+		ri     rangeIterator
+		result [][2]time.Time
+	}{
+		{
+			ri: rangeIterator{
+				start: parseTime(t, "2021-01-01T12:00:00.000Z"),
+				end:   parseTime(t, "2021-01-01T12:30:00.000Z"),
+				step:  5 * time.Minute,
+			},
+			result: [][2]time.Time{
+				{parseTime(t, "2021-01-01T12:00:00.000Z"), parseTime(t, "2021-01-01T12:05:00.000Z")},
+				{parseTime(t, "2021-01-01T12:05:00.000Z"), parseTime(t, "2021-01-01T12:10:00.000Z")},
+				{parseTime(t, "2021-01-01T12:10:00.000Z"), parseTime(t, "2021-01-01T12:15:00.000Z")},
+				{parseTime(t, "2021-01-01T12:15:00.000Z"), parseTime(t, "2021-01-01T12:20:00.000Z")},
+				{parseTime(t, "2021-01-01T12:20:00.000Z"), parseTime(t, "2021-01-01T12:25:00.000Z")},
+				{parseTime(t, "2021-01-01T12:25:00.000Z"), parseTime(t, "2021-01-01T12:30:00.000Z")},
+			},
+		},
+		{
+			ri: rangeIterator{
+				start: parseTime(t, "2021-01-01T12:00:00.000Z"),
+				end:   parseTime(t, "2021-01-01T12:30:00.000Z"),
+				step:  45 * time.Minute,
+			},
+			result: [][2]time.Time{
+				{parseTime(t, "2021-01-01T12:00:00.000Z"), parseTime(t, "2021-01-01T12:30:00.000Z")},
+				{parseTime(t, "2021-01-01T12:30:00.000Z"), parseTime(t, "2021-01-01T12:30:00.000Z")},
+			},
+		},
+		{
+			ri: rangeIterator{
+				start: parseTime(t, "2021-01-01T12:00:12.000Z"),
+				end:   parseTime(t, "2021-01-01T12:00:17.000Z"),
+				step:  time.Second,
+			},
+			result: [][2]time.Time{
+				{parseTime(t, "2021-01-01T12:00:12.000Z"), parseTime(t, "2021-01-01T12:00:13.000Z")},
+				{parseTime(t, "2021-01-01T12:00:13.000Z"), parseTime(t, "2021-01-01T12:00:14.000Z")},
+				{parseTime(t, "2021-01-01T12:00:14.000Z"), parseTime(t, "2021-01-01T12:00:15.000Z")},
+				{parseTime(t, "2021-01-01T12:00:15.000Z"), parseTime(t, "2021-01-01T12:00:16.000Z")},
+				{parseTime(t, "2021-01-01T12:00:16.000Z"), parseTime(t, "2021-01-01T12:00:17.000Z")},
+			},
+		},
+	}
+
+	for i, tc := range testCases {
+		t.Run(fmt.Sprintf("case %d", i), func(t *testing.T) {
+			var j int
+			for tc.ri.next() {
+				if len(tc.result) < j+1 {
+					t.Fatalf("unexpected result for iterator on step %d: %v - %v",
+						j, tc.ri.s, tc.ri.e)
+				}
+				s, e := tc.ri.s, tc.ri.e
+				expS, expE := tc.result[j][0], tc.result[j][1]
+				if s != expS {
+					t.Fatalf("expected to get start=%v; got %v", expS, s)
+				}
+				if e != expE {
+					t.Fatalf("expected to get end=%v; got %v", expE, e)
+				}
+				j++
+			}
+		})
+	}
+}
+
+func parseTime(t *testing.T, s string) time.Time {
+	t.Helper()
+	tt, err := time.Parse("2006-01-02T15:04:05.000Z", s)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return tt
+}

app/vmalert/rule.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"time"
+)
+
+// Rule represents alerting or recording rule
+// that has unique ID, can be Executed and
+// updated with other Rule.
+type Rule interface {
+	// ID returns unique ID that may be used for
+	// identifying this Rule among others.
+	ID() uint64
+	// Exec executes the rule with given context
+	Exec(ctx context.Context) ([]prompbmarshal.TimeSeries, error)
+	// ExecRange executes the rule on the given time range
+	ExecRange(ctx context.Context, start, end time.Time) ([]prompbmarshal.TimeSeries, error)
+	// UpdateWith performs modification of current Rule
+	// with fields of the given Rule.
+	UpdateWith(Rule) error
+	// Close performs the shutdown procedures for rule
+	// such as metrics unregister
+	Close()
+}
+
+var errDuplicate = errors.New("result contains metrics with the same labelset after applying rule labels")

app/vmalert/tpl/footer.qtpl

@@ -0,0 +1,36 @@
+{% func Footer() %}
+        </main>
+        <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM" crossorigin="anonymous"></script>
+        <script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
+        <script type="text/javascript">
+            function expandAll() {
+               $('.collapse').addClass('show');
+            }
+            function collapseAll() {
+               $('.collapse').removeClass('show');
+            }
+
+            $(document).ready(function() {
+              // prevent collapse logic on link click
+              $(".group-heading a").click(function(e) {
+                e.stopPropagation();
+              });
+
+              $(".group-heading").click(function(e) {
+                 let target = $(this).attr('data-bs-target');
+                 let el = $('#'+target);
+                  new bootstrap.Collapse(el, {
+                    toggle: true
+                  });
+              });
+
+              var hash = window.location.hash.substr(1);
+              let group = $('#'+hash);
+              if (group.length > 0) {
+                group.click();
+              }
+            });
+        </script>
+    </body>
+</html>
+{% endfunc %}