CHANGELOG.md: cut v1.45.0

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/850

.github/workflows/github-pages.yml

@@ -2,7 +2,7 @@ name: github-pages
 on:
   push:
     paths:
-      - 'docs/*.md'
+      - 'docs/*'
       - 'README.md'
     branches:
       - master
@@ -17,14 +17,14 @@ jobs:
           TOKEN: ${{secrets.CI_TOKEN}}
         run: |
           git clone https://vika:${TOKEN}@github.com/VictoriaMetrics/VictoriaMetrics.github.io.git gpages
-          cp docs/*.md gpages
+          cp docs/* gpages
           cp README.md gpages
           cd gpages
           git config --local user.email "info@victoriametrics.com"
           git config --local user.name "Vika"
-          git add "*.md"
+          git add .
           git commit -m "update github pages"
           remote_repo="https://vika:${TOKEN}@github.com/VictoriaMetrics/VictoriaMetrics.github.io.git"
           git push "${remote_repo}"
           cd ..
-          rm -rf gpages
+          rm -rf gpages

.github/workflows/main.yml

@@ -14,18 +14,19 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Setup Go
-        uses: actions/setup-go@v1
+        uses: actions/setup-go@main
         with:
-          go-version: 1.13
+          go-version: 1.15
         id: go
-      - name: Code checkout
-        uses: actions/checkout@v1
       - name: Dependencies
         env:
-          GO111MODULE: off
+          GO111MODULE: on
         run: |
-          go get -v golang.org/x/lint/golint
+          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 v1.27.0
+      - name: Code checkout
+        uses: actions/checkout@master
       - name: Build
         env:
           GO111MODULE: on
@@ -42,9 +43,22 @@ jobs:
           make victoria-metrics-arm64
           make vmutils
           GOOS=freebsd go build -mod=vendor ./app/victoria-metrics
+          GOOS=freebsd go build -mod=vendor ./app/vmagent
+          GOOS=freebsd go build -mod=vendor ./app/vmalert
+          GOOS=freebsd go build -mod=vendor ./app/vmbackup
+          GOOS=freebsd go build -mod=vendor ./app/vmrestore
+          GOOS=openbsd go build -mod=vendor ./app/victoria-metrics
+          GOOS=openbsd go build -mod=vendor ./app/vmagent
+          GOOS=openbsd go build -mod=vendor ./app/vmalert
+          GOOS=openbsd go build -mod=vendor ./app/vmbackup
+          GOOS=openbsd go build -mod=vendor ./app/vmrestore
           GOOS=darwin go build -mod=vendor ./app/victoria-metrics
+          GOOS=darwin go build -mod=vendor ./app/vmagent
+          GOOS=darwin go build -mod=vendor ./app/vmalert
+          GOOS=darwin go build -mod=vendor ./app/vmbackup
+          GOOS=darwin go build -mod=vendor ./app/vmrestore
       - name: Publish coverage
-        uses: codecov/codecov-action@v1.0.4
+        uses: codecov/codecov-action@v1.0.6
         with:
           token: ${{secrets.CODECOV_TOKEN}}
           file: ./coverage.txt

.github/workflows/wiki.yml

@@ -2,7 +2,7 @@ name: wiki
 on:
   push:
     paths:
-      - 'docs/*.md'
+      - 'docs/*'
     branches:
       - master
 jobs:
@@ -15,15 +15,14 @@ jobs:
         env:
           TOKEN: ${{secrets.CI_TOKEN}}
         run: |
-          cd docs
           git clone https://vika:${TOKEN}@github.com/VictoriaMetrics/VictoriaMetrics.wiki.git wiki
-          find ./ -name '*.md' -exec cp -prv '{}' 'wiki' ';'
+          cp docs/* wiki
           cd wiki
           git config --local user.email "info@victoriametrics.com"
           git config --local user.name "Vika"
-          git add "*.md"
+          git add .
           git commit -m "update wiki pages"
           remote_repo="https://vika:${TOKEN}@github.com/VictoriaMetrics/VictoriaMetrics.wiki.git"
           git push "${remote_repo}"
           cd ..
-          rm -rf wiki
+          rm -rf wiki

CHANGELOG.md

@@ -0,0 +1,149 @@
+# tip
+
+
+# [v1.45.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.45.0)
+
+* FEATURE: allow setting `-retentionPeriod` smaller than one month. I.e. `-retentionPeriod=3d`, `-retentionPeriod=2w`, etc. is supported now.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/173
+* FEATURE: optimize more cases according to https://utcc.utoronto.ca/~cks/space/blog/sysadmin/PrometheusLabelNonOptimization . Now the following cases are optimized too:
+  * `rollup_func(foo{filters}[d]) op bar` -> `rollup_func(foo{filters}[d]) op bar{filters}`
+  * `transform_func(foo{filters}) op bar` -> `transform_func(foo{filters}) op bar{filters}`
+  * `num_or_scalar op foo{filters} op bar` -> `num_or_scalar op foo{filters} op bar{filters}`
+* FEATURE: improve time series search for queries with multiple label filters. I.e. `foo{label1="value", label2=~"regexp"}`.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/781
+* FEATURE: vmagent: add `stream parse` mode. This mode allows reducing memory usage when individual scrape targets expose tens of millions of metrics.
+  For example, during scraping Prometheus in [federation](https://prometheus.io/docs/prometheus/latest/federation/) mode.
+  See `-promscrape.streamParse` command-line option and `stream_parse: true` config option for `scrape_config` section in `-promscrape.config`.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/825 and [troubleshooting docs for vmagent](https://victoriametrics.github.io/vmagent.html#troubleshooting).
+* FEATURE: vmalert: add `-dryRun` command-line option for validating the provided config files without the need to start `vmalert` service.
+* FEATURE: accept optional third argument of string type at `topk_*` and `bottomk_*` functions. This is label name for additional time series to return with the sum of time series outside top/bottom K. See [MetricsQL docs](https://victoriametrics.github.io/MetricsQL.html) for more details.
+* FEATURE: vmagent: expose `/api/v1/targets` page according to [the corresponding Prometheus API](https://prometheus.io/docs/prometheus/latest/querying/api/#targets).
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/643
+
+* BUGFIX: vmagent: properly handle OpenStack endpoint ending with `v3.0` such as `https://ostack.example.com:5000/v3.0`
+  in the same way as Prometheus does. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/728#issuecomment-709914803
+* BUGFIX: drop trailing data points for time series with a single raw sample. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/748
+* BUGFIX: do not drop trailing data points for instant queries to `/api/v1/query`. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/845
+* BUGFIX: vmbackup: fix panic when `-origin` isn't specified. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/856
+* BUGFIX: vmalert: skip automatically added labels on alerts restore. Label `alertgroup` was introduced in [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/611)
+  and automatically added to generated time series. By mistake, this new label wasn't correctly purged on restore event and affected alert's ID uniqueness.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/870
+* BUGFIX: vmagent: fix panic at scrape error body formating. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/864
+* BUGFIX: vmagent: add leading missing slash to metrics path like Prometheus does. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/835
+* BUGFIX: vmagent: drop packet if remote storage returns 4xx status code. This make the behaviour consistent with Prometheus.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/873
+* BUGFIX: vmagent: properly handle 301 redirects. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/869
+
+
+# [v1.44.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.44.0)
+
+* FEATURE: automatically add missing label filters to binary operands as described at https://utcc.utoronto.ca/~cks/space/blog/sysadmin/PrometheusLabelNonOptimization .
+  This should improve performance for queries with missing label filters in binary operands. For example, the following query should work faster now, because it shouldn't
+  fetch and discard time series for `node_filesystem_files_free` metric without matching labels for the left side of the expression:
+  ```
+     node_filesystem_files{ host="$host", mountpoint="/" } - node_filesystem_files_free
+  ```
+* FEATURE: vmagent: add Docker Swarm service discovery (aka [dockerswarm_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#dockerswarm_sd_config)).
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/656
+* FEATURE: add ability to export data in CSV format. See [these docs](https://victoriametrics.github.io/#how-to-export-csv-data) for details.
+* FEATURE: vmagent: add `-promscrape.suppressDuplicateScrapeTargetErrors` command-line flag for suppressing `duplicate scrape target` errors.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/651 and https://victoriametrics.github.io/vmagent.html#troubleshooting .
+* FEATURE: vmagent: show original labels before relabeling is applied on `duplicate scrape target` errors. This should simplify debugging for incorrect relabeling.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/651
+* FEATURE: vmagent: `/targets` page now accepts optional `show_original_labels=1` query arg for displaying original labels for each target before relabeling is applied.
+  This should simplify debugging for target relabeling configs. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/651
+* FEATURE: add `-finalMergeDelay` command-line flag for configuring the delay before final merge for per-month partitions.
+  The final merge is started after no new data is ingested into per-month partition during `-finalMergeDelay`.
+* FEATURE: add `vm_rows_added_to_storage_total` metric, which shows the total number of rows added to storage since app start.
+  The `sum(rate(vm_rows_added_to_storage_total))` can be smaller than `sum(rate(vm_rows_inserted_total))` if certain metrics are dropped
+  due to [relabeling](https://victoriametrics.github.io/#relabeling). The `sum(rate(vm_rows_added_to_storage_total))` can be bigger
+  than `sum(rate(vm_rows_inserted_total))` if [replication](https://victoriametrics.github.io/Cluster-VictoriaMetrics.html#replication-and-data-safety) is enabled.
+* FEATURE: keep metric name after applying [MetricsQL](https://victoriametrics.github.io/MetricsQL.html) functions, which don't change time series meaning.
+  The list of such functions:
+   * `keep_last_value`
+   * `keep_next_value`
+   * `interpolate`
+   * `running_min`
+   * `running_max`
+   * `running_avg`
+   * `range_min`
+   * `range_max`
+   * `range_avg`
+   * `range_first`
+   * `range_last`
+   * `range_quantile`
+   * `smooth_exponential`
+   * `ceil`
+   * `floor`
+   * `round`
+   * `clamp_min`
+   * `clamp_max`
+   * `max_over_time`
+   * `min_over_time`
+   * `avg_over_time`
+   * `quantile_over_time`
+   * `mode_over_time`
+   * `geomean_over_time`
+   * `holt_winters`
+   * `predict_linear`
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/674
+
+* BUGFIX: properly handle stale time series after K8S deployment. Previously such time series could be double-counted.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/748
+* BUGFIX: return a single time series at max from `absent()` function like Prometheus does.
+* BUGFIX: vmalert: accept days, weeks and years in `for: ` part of config like Prometheus does. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/817
+* BUGFIX: fix `mode_over_time(m[d])` calculations. Previously the function could return incorrect results.
+
+
+# [v1.43.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.43.0)
+
+* FEATURE: reduce CPU usage for repeated queries over sliding time window when no new time series are added to the database.
+  Typical use cases: repeated evaluation of alerting rules in [vmalert](https://victoriametrics.github.io/vmalert.html) or dashboard auto-refresh in Grafana.
+* FEATURE: vmagent: add OpenStack service discovery aka [openstack_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#openstack_sd_config).
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/728 .
+* FEATURE: vmalert: make `-maxIdleConnections` configurable for datasource HTTP client. This option can be used for minimizing connection churn.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/795 .
+* FEATURE: add `-influx.maxLineSize` command-line flag for configuring the maximum size for a single Influx line during parsing.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/807
+
+* BUGFIX: properly handle `inf` values during [background merge of LSM parts](https://medium.com/@valyala/how-victoriametrics-makes-instant-snapshots-for-multi-terabyte-time-series-data-e1f3fb0e0282).
+  Previously `Inf` values could result in `NaN` values for adjancent samples in time series. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/805 .
+* BUGFIX: fill gaps on graphs for `range_*` and `running_*` functions. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/806 .
+* BUGFIX: make a copy of label with new name during relabeling with `action: labelmap` in the same way as Prometheus does.
+  Previously the original label name has been replaced. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/812 .
+* BUGFIX: support parsing floating-point timestamp like Graphite Carbon does. Such timestmaps are truncated to seconds.
+
+
+# [v1.42.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.42.0)
+
+* FEATURE: use all the available CPU cores when accepting data via a single TCP connection
+  for [all the supported protocols](https://victoriametrics.github.io/#how-to-import-time-series-data).
+  Previously data ingested via a single TCP connection could use only a single CPU core. This could limit data ingestion performance.
+  The main benefit of this feature is that data can be imported at max speed via a single connection - there is no need to open multiple concurrent
+  connections to VictoriaMetrics or [vmagent](https://victoriametrics.github.io/vmagent.html) in order to achieve the maximum data ingestion speed.
+* FEATURE: cluster: improve performance for data ingestion path from `vminsert` to `vmstorage` nodes. The maximum data ingestion performance
+  for a single connection between `vminsert` and `vmstorage` node scales with the number of available CPU cores on `vmstorage` side.
+  This should help with https://github.com/VictoriaMetrics/VictoriaMetrics/issues/791 .
+* FEATURE: add ability to export / import data in native format via `/api/v1/export/native` and `/api/v1/import/native`.
+  This is the most optimized approach for data migration between VictoriaMetrics instances. Both single-node and cluster instances are supported.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/787#issuecomment-700632551 .
+* FEATURE: add `reduce_mem_usage` query option to `/api/v1/export` in order to reduce memory usage during data export / import.
+  See [these docs](https://victoriametrics.github.io/#how-to-export-data-in-json-line-format) for details.
+* FEATURE: improve performance for `/api/v1/series` handler when it returns big number of time series.
+* FEATURE: add `vm_merge_need_free_disk_space` metric, which can be used for estimating the number of deferred background data merges due to the lack of free disk space.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/686 .
+* FEATURE: add OpenBSD support. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/785 .
+
+* BUGFIX: properly apply `-search.maxStalenessInterval` command-line flag value. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/784 .
+* BUGFIX: fix displaying data in Grafana tables. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/720 .
+* BUGFIX: do not adjust the number of detected CPU cores found at `/sys/devices/system/cpu/online`.
+  The adjustement was increasing the resulting GOMAXPROC by 1, which looked confusing to users.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/685#issuecomment-698595309 .
+* BUGFIX: vmagent: do not show `-remoteWrite.url` in initial logs if `-remoteWrite.showURL` isn't set. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/773 .
+* BUGFIX: properly handle case when [/metrics/find](https://victoriametrics.github.io/#graphite-metrics-api-usage) finds both a leaf and a node for the given `query=prefix.*`.
+  In this case only the node must be returned with stripped dot in the end of id as carbonapi does.
+
+
+# Previous releases
+
+See [releases page](https://github.com/VictoriaMetrics/VictoriaMetrics/releases).

Makefile

@@ -13,6 +13,8 @@ GO_BUILDINFO = -X '$(PKG_PREFIX)/lib/buildinfo.Version=$(APP_NAME)-$(shell date
 all: \
 	victoria-metrics-prod \
 	vmagent-prod \
+	vmalert-prod \
+	vmauth-prod \
 	vmbackup-prod \
 	vmrestore-prod
 
@@ -25,17 +27,23 @@ clean:
 publish: \
 	publish-victoria-metrics \
 	publish-vmagent \
+	publish-vmalert \
+	publish-vmauth \
 	publish-vmbackup \
 	publish-vmrestore
 
 package: \
 	package-victoria-metrics \
 	package-vmagent \
+	package-vmalert \
+	package-vmauth \
 	package-vmbackup \
 	package-vmrestore
 
 vmutils: \
 	vmagent \
+	vmalert \
+	vmauth \
 	vmbackup \
 	vmrestore
 
@@ -49,9 +57,11 @@ release-victoria-metrics: victoria-metrics-prod
 
 release-vmutils: \
 	vmagent-prod \
+	vmalert-prod \
+	vmauth-prod \
 	vmbackup-prod \
 	vmrestore-prod
-	cd bin && tar czf vmutils-$(PKG_TAG).tar.gz vmagent-prod vmbackup-prod vmrestore-prod && \
+	cd bin && tar czf vmutils-$(PKG_TAG).tar.gz vmagent-prod vmalert-prod vmauth-prod vmbackup-prod vmrestore-prod && \
 		sha256sum vmutils-$(PKG_TAG).tar.gz > vmutils-$(PKG_TAG)_checksums.txt
 
 pprof-cpu:
@@ -78,9 +88,10 @@ errcheck: install-errcheck
 	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/vmalert/...
 
 install-errcheck:
 	which errcheck || GO111MODULE=off go get -u github.com/kisielk/errcheck
@@ -90,6 +101,9 @@ check-all: fmt vet lint errcheck golangci-lint
 test:
 	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/...
 
@@ -119,6 +133,9 @@ app-local:
 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)
+
 quicktemplate-gen: install-qtc
 	qtc
 
@@ -127,7 +144,15 @@ install-qtc:
 
 
 golangci-lint: install-golangci-lint
-	golangci-lint run --exclude '(SA4003|SA1019):' -D errcheck -D structcheck
+	golangci-lint run --exclude '(SA4003|SA1019|SA5011):' -D errcheck -D structcheck --timeout 2m
 
 install-golangci-lint:
 	which golangci-lint || GO111MODULE=off go get -u github.com/golangci/golangci-lint/cmd/golangci-lint
+
+docs-sync:
+	cp app/vmagent/README.md docs/vmagent.md
+	cp app/vmalert/README.md docs/vmalert.md
+	cp app/vmauth/README.md docs/vmauth.md
+	cp app/vmbackup/README.md docs/vmbackup.md
+	cp app/vmrestore/README.md docs/vmrestore.md
+	cp README.md docs/Single-server-VictoriaMetrics.md

app/victoria-metrics/Makefile

@@ -3,6 +3,9 @@
 victoria-metrics:
 	APP_NAME=victoria-metrics $(MAKE) app-local
 
+victoria-metrics-race:
+	APP_NAME=victoria-metrics RACE=-race $(MAKE) app-local
+
 victoria-metrics-prod:
 	APP_NAME=victoria-metrics $(MAKE) app-via-docker
 

app/victoria-metrics/deployment/Dockerfile

@@ -1,8 +1,8 @@
-ARG certs_image
-FROM $certs_image AS certs
-FROM scratch
-COPY --from=certs /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
+ARG base_image
+FROM $base_image
+
+EXPOSE 8428
+
+ENTRYPOINT ["/victoria-metrics-prod"]
 ARG src_binary
 COPY $src_binary ./victoria-metrics-prod
-EXPOSE 8428
-ENTRYPOINT ["/victoria-metrics-prod"]

app/victoria-metrics/main.go

@@ -2,13 +2,16 @@ package main
 
 import (
 	"flag"
+	"fmt"
 	"net/http"
+	"os"
 	"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/cgroup"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envflag"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
@@ -25,9 +28,12 @@ var (
 )
 
 func main() {
+	// Write flags and help message to stdout, since it is easier to grep or pipe.
+	flag.CommandLine.SetOutput(os.Stdout)
 	envflag.Parse()
 	buildinfo.Init()
 	logger.Init()
+	cgroup.UpdateGOMAXPROCSToCPUQuota()
 	logger.Infof("starting VictoriaMetrics at %q...", *httpListenAddr)
 	startTime := time.Now()
 	storage.SetMinScrapeIntervalForDeduplication(*minScrapeInterval)
@@ -61,6 +67,10 @@ func main() {
 }
 
 func requestHandler(w http.ResponseWriter, r *http.Request) bool {
+	if r.RequestURI == "/" {
+		fmt.Fprintf(w, "Single-node VictoriaMetrics. See docs at https://victoriametrics.github.io/")
+		return true
+	}
 	if vminsert.RequestHandler(w, r) {
 		return true
 	}

app/victoria-metrics/main_test.go

@@ -373,7 +373,7 @@ func checkMetricsResult(got, want []Metric) error {
 		want = removeIfFoundMetrics(r, want)
 	}
 	if len(want) > 0 {
-		return fmt.Errorf("exptected metrics %+v not found in %+v", want, got)
+		return fmt.Errorf("expected metrics %+v not found in %+v", want, got)
 	}
 	return nil
 }

app/victoria-metrics/self_scraper.go

@@ -14,7 +14,11 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/storage"
 )
 
-var selfScrapeInterval = flag.Duration("selfScrapeInterval", 0, "Interval for self-scraping own metrics at /metrics page")
+var (
+	selfScrapeInterval = flag.Duration("selfScrapeInterval", 0, "Interval for self-scraping own metrics at /metrics page")
+	selfScrapeInstance = flag.String("selfScrapeInstance", "self", "Value for 'instance' label, which is added to self-scraped metrics")
+	selfScrapeJob      = flag.String("selfScrapeJob", "victoria-metrics", "Value for 'job' label, which is added to self-scraped metrics")
+)
 
 var selfScraperStopCh chan struct{}
 var selfScraperWG sync.WaitGroup
@@ -65,8 +69,8 @@ func selfScraper(scrapeInterval time.Duration) {
 			r := &rows.Rows[i]
 			labels = labels[:0]
 			labels = addLabel(labels, "", r.Metric)
-			labels = addLabel(labels, "job", "victoria-metrics")
-			labels = addLabel(labels, "instance", "self")
+			labels = addLabel(labels, "job", *selfScrapeJob)
+			labels = addLabel(labels, "instance", *selfScrapeInstance)
 			for j := range r.Tags {
 				t := &r.Tags[j]
 				labels = addLabel(labels, t.Key, t.Value)
@@ -81,7 +85,6 @@ func selfScraper(scrapeInterval time.Duration) {
 			mr.Timestamp = currentTimestamp
 			mr.Value = r.Value
 		}
-		logger.Infof("writing %d rows at timestamp %d", len(mrs), currentTimestamp)
 		vmstorage.AddRows(mrs)
 	}
 }

app/victoria-metrics/testdata/graphite/empty-label-match.json

@@ -0,0 +1,16 @@
+{
+  "name": "empty-label-match",
+  "issue": "https://github.com/VictoriaMetrics/VictoriaMetrics/issues/395",
+  "data": [
+    "empty_label_match 1 {TIME_S-1m}",
+    "empty_label_match;foo=bar 2 {TIME_S-1m}",
+    "empty_label_match;foo=baz 3 {TIME_S-1m}"],
+  "query": ["/api/v1/query_range?query=empty_label_match{foo=~'bar|'}&start={TIME_S-1m}&end={TIME_S}&step=60"],
+  "result_query_range": {
+    "status":"success",
+    "data":{"resultType":"matrix",
+      "result":[
+	      {"metric":{"__name__":"empty_label_match"},"values":[["{TIME_S-1m}","1"],["{TIME_S}","1"]]},
+	      {"metric":{"__name__":"empty_label_match","foo":"bar"},"values":[["{TIME_S-1m}","2"],["{TIME_S}","2"]]}
+      ]}}
+}

app/victoria-metrics/testdata/graphite/max_lookback_set.json

@@ -16,6 +16,8 @@
 	      ["{TIME_S-120s}","3"],
 	      ["{TIME_S-60s}","2"],
 	      ["{TIME_S-30s}","1"],
-	      ["{TIME_S-20s}","1"]
+	      ["{TIME_S-20s}","1"],
+	      ["{TIME_S-10s}","1"],
+	      ["{TIME_S-0s}","1"]
       ]}]}}
 }

app/victoria-metrics/testdata/graphite/subquery-aggregation.json

@@ -9,6 +9,6 @@
   "query": ["/api/v1/query?query=min%20by%20(item)%20(min_over_time(forms_daily_count[10m:1m]))&time={TIME_S-1m}"],
   "result_query": {
     "status":"success",
-    "data":{"resultType":"vector","result":[{"metric":{"item":"x"},"value":["{TIME_S-1m}","1"]},{"metric":{"item":"y"},"value":["{TIME_S-1m}","3"]}]}
+    "data":{"resultType":"vector","result":[{"metric":{"item":"x"},"value":["{TIME_S-1m}","2"]},{"metric":{"item":"y"},"value":["{TIME_S-1m}","4"]}]}
   }
 }

app/vmagent/Makefile

@@ -3,6 +3,9 @@
 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
 
@@ -49,25 +52,29 @@ publish-vmagent:
 	APP_NAME=vmagent $(MAKE) publish-via-docker
 
 run-vmagent:
-	mkdir -p vmagent-data
-	DOCKER_OPTS='-v $(shell pwd)/vmagent-data:/vmagent-data' \
+	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 GOOS=linux GOARCH=amd64 GO111MODULE=on go build -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/vmagent-amd64 ./app/vmagent
+	CGO_ENABLED=1 GOARCH=amd64 $(MAKE) vmagent-local-with-goarch
 
 vmagent-arm:
-	CGO_ENABLED=0 GOOS=linux GOARCH=arm GO111MODULE=on go build -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/vmagent-arm ./app/vmagent
+	CGO_ENABLED=0 GOARCH=arm $(MAKE) vmagent-local-with-goarch
 
 vmagent-arm64:
-	CGO_ENABLED=0 GOOS=linux GOARCH=arm64 GO111MODULE=on go build -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/vmagent-arm64 ./app/vmagent
+	CGO_ENABLED=0 GOARCH=arm64 $(MAKE) vmagent-local-with-goarch
 
 vmagent-ppc64le:
-	CGO_ENABLED=0 GOOS=linux GOARCH=ppc64le GO111MODULE=on go build -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/vmagent-ppc64le ./app/vmagent
+	CGO_ENABLED=0 GOARCH=ppc64le $(MAKE) vmagent-local-with-goarch
 
 vmagent-386:
-	CGO_ENABLED=0 GOOS=linux GOARCH=386 GO111MODULE=on go build -mod=vendor -ldflags "$(GO_BUILDINFO)" -o bin/vmagent-386 ./app/vmagent
+	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

app/vmagent/README.md

@@ -1,7 +1,8 @@
 ## vmagent
 
-`vmagent` is a tiny but brave agent, which helps you collecting metrics from various sources
-and storing them to [VictoriaMetrics](https://github.com/VictoriaMetrics/VictoriaMetrics).
+`vmagent` is a tiny but brave agent, which helps you collect metrics from various sources
+and stores them in [VictoriaMetrics](https://github.com/VictoriaMetrics/VictoriaMetrics)
+or any other Prometheus-compatible storage system that supports the `remote_write` protocol.
 
 <img alt="vmagent" src="vmagent.png">
 
@@ -10,7 +11,7 @@ and storing them to [VictoriaMetrics](https://github.com/VictoriaMetrics/Victori
 
 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 to VictoriaMetrics.
-Also, we found that users’ infrastructure is like snowflakes - never alike, and we decided to add more flexibility
+Also, we found that users’ infrastructure are snowflakes - no two are alike, and we decided to add more flexibility
 to `vmagent` (like the ability to push metrics instead of pulling them). We did our best and plan to do even more.
 
 
@@ -18,18 +19,21 @@ to `vmagent` (like the ability to push metrics instead of pulling them). We did
 
 * Can be used as 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 add, remove and modify labels via Prometheus relabeling. See [these docs](#relabeling) for details.
+* 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 the ingestion protocols supported by VictoriaMetrics:
   * Influx line protocol via `http://<vmagent>:8429/write`. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-send-data-from-influxdb-compatible-agents-such-as-telegraf).
-  * JSON lines import protocol via `http://<vmagent>:8429/api/v1/import`. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-import-time-series-data).
   * Graphite plaintext protocol if `-graphiteListenAddr` command-line flag is set. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#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://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#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://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-import-data-in-json-line-format).
+  * Native data import protocol via `http://<vmagent>:8429/api/v1/import/native`. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-import-data-in-native-format).
+  * Data in Prometheus exposition format. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#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://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-import-csv-data).
 * Can replicate collected metrics simultaneously to multiple remote storage systems.
 * Works 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 connection
   to remote storage is recovered. The maximum disk usage for the buffer can be limited with `-remoteWrite.maxDiskUsagePerURL`.
-* Uses lower amounts of RAM, CPU, disk IO and network bandwidth comparing to Prometheus.
+* Uses lower amounts of RAM, CPU, disk IO and network bandwidth compared to Prometheus.
 
 
 ### Quick Start
@@ -38,8 +42,7 @@ Just download `vmutils-*` archive from [releases page](https://github.com/Victor
 and pass the following flags to `vmagent` binary in order to start scraping Prometheus targets:
 
 * `-promscrape.config` with the path to Prometheus config file (it is usually located at `/etc/prometheus/prometheus.yml`)
-* `-remoteWrite.url` with the remote storage endpoint such as VictoriaMetrics. Multiple `-remoteWrite.url` args can be set in parallel
-  in order to replicate data concurrently to multiple remote storage systems.
+* `-remoteWrite.url` with the remote storage endpoint such as VictoriaMetrics. The `-remoteWrite.url` argument can be specified multiple times in order to replicate data concurrently to an arbitrary number of remote storage systems.
 
 Example command line:
 
@@ -47,20 +50,73 @@ Example command line:
 /path/to/vmagent -promscrape.config=/path/to/prometheus.yml -remoteWrite.url=https://victoria-metrics-host:8428/api/v1/write
 ```
 
-If you need collecting only Influx data, then the following command line would be enough:
+If you only need to collect Influx data, then the following is sufficient:
 
 ```
 /path/to/vmagent -remoteWrite.url=https://victoria-metrics-host:8428/api/v1/write
 ```
 
-Then send Influx data to `http://vmagent-host:8429/write`. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-send-data-from-influxdb-compatible-agents-such-as-telegraf) for more details.
+Then send Influx data to `http://vmagent-host:8429`. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#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/).
+`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.
 
 
-### How to collect metrics in Prometheus format?
+### Use cases
+
+
+#### IoT and Edge monitoring
+
+`vmagent` can run and collect metrics in IoT and industrial networks with unreliable or scheduled connections to the 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 on any errors.
+The maximum buffer size can be limited with `-remoteWrite.maxDiskUsagePerURL`.
+
+`vmagent` works on various architectures from 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 these metrics to remote storage,
+then `vmagent` can replace such Prometheus setup. Usually `vmagent` requires lower amounts of RAM, CPU and network bandwidth comparing to Prometheus for such a setup.
+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 instances.
+`vmagent` buffers the collected data in files at `-remoteWrite.tmpDataPath` until the remote storage becomes available again.
+Then it sends the buffered data to the remote storage in order to prevent data gaps in the remote storage.
+
+
+#### Relabeling and filtering
+
+`vmagent` can add, remove or update labels on the collected data before sending it to remote storage. Additionally,
+it can remove unwanted samples via Prometheus-like relabeling before sending the collected data to remote storage.
+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 instance, it is possible to replicate or split
+data among long-term remote storage, short-term remote storage and real-time analytical system [built on top of Kafka](https://github.com/Telefonica/prometheus-kafka-adapter).
+Note that each destination can receive its own subset of the collected data thanks to per-destination relabeling via `-remoteWrite.urlRelabelConfig`.
+
+
+#### Prometheus remote_write proxy
+
+`vmagent` may be used as a proxy for Prometheus data sent via Prometheus `remote_write` protocol. It can accept data via `remote_write` API
+at `/api/v1/write` endpoint, apply relabeling and filtering and then proxy it to another `remote_write` systems.
+The `vmagent` can be configured to encrypt the incoming `remote_write` requests with `-tls*` command-line flags.
+Additionally, Basic Auth can be enabled for the incoming `remote_write` requests with `-httpAuth.*` command-line flags.
+
+
+
+### How to collect metrics in Prometheus format
 
 Pass the path to `prometheus.yml` to `-promscrape.config` command-line flag. `vmagent` takes into account the following
 sections from [Prometheus config file](https://prometheus.io/docs/prometheus/latest/configuration/configuration/):
@@ -76,18 +132,43 @@ The following scrape types in [scrape_config](https://prometheus.io/docs/prometh
 * `static_configs` - for scraping statically defined targets. See [these docs](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#static_config) for details.
 * `file_sd_configs` - 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.
-
-The following service discovery mechanisms will be added to `vmagent` soon:
-
-* [kubernetes_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#kubernetes_sd_config)
-* [ec2_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#ec2_sd_config)
-* [gce_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#gce_sd_config)
-* [consul_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#consul_sd_config)
-* [dns_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#dns_sd_config)
-
+* `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` - 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 `profile` config param and aws credentials file yet.
+* `gce_sd_configs` - 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 equals to `"*"`, then `vmagent` discovers all the zones for the given project;
+  * `zone` may contain arbitrary number of zones, i.e. `zone: [us-east1-a, us-east1-b]`.
+* `consul_sd_configs` - for scraping targets registered in Consul.
+  See [consul_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#consul_sd_config) for details.
+* `dns_sd_configs` - 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` - 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.
+* `dockerswarm_sd_configs` - for scraping Docker Swarm targets.
+  See [dockerswarm_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#dockerswarm_sd_config) for details.
 
 File feature requests at [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_config` section:
+
+* `disable_compression: true` - for disabling response compression on a per-job basis. By default `vmagent` requests compressed responses from scrape targets
+  in order to save network bandwidth.
+* `disable_keepalive: true` - for disabling [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 in order to reduce overhead on connection re-establishing.
+
+Note that `vmagent` doesn't support `refresh_interval` option 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 `-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.
+
 
 ### Adding labels to metrics
 
@@ -104,12 +185,13 @@ Additionally it provides the following extra actions:
 
 * `replace_all`: replaces all the occurences of `regex` in the values of `source_labels` with the `replacement` and stores the result in the `target_label`.
 * `labelmap_all`: replaces all the occurences of `regex` in all the label names with the `replacement`.
+* `keep_if_equal`: keeps the entry if all label values from `source_labels` are equal.
+* `drop_if_equal`: drops the entry if all the label values from `source_labels` are equal.
 
 The relabeling can be defined in the following places:
 
-* At `scrape_config -> relabel_configs` section in `-promscrape.config` file. This relabeling is applied to targets when parsing the file during `vmagent` startup
-  or during config reload after sending `SIGHUP` signal to `vmagent`  via `kill -HUP`.
-* At `scrape_config -> metric_relabel_configs` section in `-promscrape.config` file. This relabeling is applied to metrics after each scrape for the configured targets.
+* At `scrape_config -> relabel_configs` section in `-promscrape.config` file. This relabeling is applied to target labels.
+* At `scrape_config -> metric_relabel_configs` section in `-promscrape.config` file. This relabeling is applied to all the scraped metrics in the given `scrape_config`.
 * At `-remoteWrite.relabelConfig` file. This relabeling is aplied to all the collected metrics before sending them to remote storage.
 * At `-remoteWrite.urlRelabelConfig` files. This relabeling is applied to metrics before sending them to the corresponding `-remoteWrite.url`.
 
@@ -126,21 +208,83 @@ Read more about relabeling in the following articles:
 
 `vmagent` exports various metrics in Prometheus exposition format at `http://vmagent-host:8429/metrics` page. It is recommended setting up regular scraping of this page
 either via `vmagent` itself or via Prometheus, so the exported metrics could be analyzed later.
+Use official [Grafana dashboard](https://grafana.com/grafana/dashboards/12683) for `vmagent` state overview.
+If you have suggestions, improvements or found a bug - feel free to open an issue on github or add review to the dashboard.
 
-`vmagent` also exports target statuses at `http://vmagent-host:8429/targets` page in plaintext format.
+`vmagent` also exports target statuses at the following handlers:
+
+* `http://vmagent-host:8429/targets`. This handler returns human-readable plaintext status for every active target.
+This page is convenient to query from 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 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).
 
 
 ### Troubleshooting
 
+* It is recommended [setting up the official Grafana dashboard](#monitoring) in order to monitor `vmagent` state.
+
 * It is recommended increasing the maximum number of open files in the system (`ulimit -n`) when scraping big number of targets,
   since `vmagent` establishes at least a single TCP connection per each target.
 
-* It is recommended increasing `-remoteWrite.queues` if `vmagent` collects more than 100K samples per second
-  and `vmagent_remotewrite_pending_data_bytes` metric exported by `vmagent` at `/metrics` page constantly grows.
+* When `vmagent` scrapes many unreliable targets, it can flood 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`.
+
+* If `vmagent` scrapes targets with millions of metrics per each target (for instance, when scraping [federation endpoints](https://prometheus.io/docs/prometheus/latest/federation/)),
+  then it is recommended enabling `stream parsing mode` in order to reduce memory usage during scraping. This mode may be enabled either globally for all the scrape targets
+  by passing `-promscrape.streamParse` command-line flag or on a per-scrape target basis with `stream_parse: true` option. For example:
+
+  ```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__!=""}']
+  ```
+
+* It is recommended to increase `-remoteWrite.queues` if `vmagent_remotewrite_pending_data_bytes` metric exported at `http://vmagent-host:8429/metrics` page constantly grows.
+
+* If you see gaps on the data pushed by `vmagent` to remote storage when `-remoteWrite.maxDiskUsagePerURL` is set, then try increasing `-remoteWrite.queues`.
+  Such gaps may appear because `vmagent` cannot keep up with sending the collected data to remote storage, so it starts dropping the buffered data
+  if the on-disk buffer size exceeds `-remoteWrite.maxDiskUsagePerURL`.
 
 * `vmagent` buffers scraped data at `-remoteWrite.tmpDataPath` directory until it is sent to `-remoteWrite.url`.
-  The directory can grow big when remote storage is unvailable during extended periods of time. If you don't want
-  sending all the data from the directory to remote storage, just stop `vmagent` and delete the directory.
+  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, 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.
+
+* If you see `skipping duplicate scrape target with identical labels` errors when scraping Kubernetes pods, then it is likely these pods listen multiple ports
+  or they use init container. These errors can be either fixed or suppressed with `-promscrape.suppressDuplicateScrapeTargetErrors` command-line flag.
+  See available options below if you prefer fixing the root cause of the error:
+
+  The following `relabel_configs` section may help determining `__meta_*` labels resulting in duplicate targets:
+  ```yml
+  - action: labelmap
+    regex: __meta_(.*)
+  ```
+
+  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
+  ```
 
 
 ### How to build from sources
@@ -150,7 +294,7 @@ It is recommended using [binary releases](https://github.com/VictoriaMetrics/Vic
 
 #### Development build
 
-1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.12.
+1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.13.
 2. Run `make vmagent` from the root folder of the repository.
    It builds `vmagent` binary and puts it into the `bin` folder.
 
@@ -165,3 +309,47 @@ It is recommended using [binary releases](https://github.com/VictoriaMetrics/Vic
 Run `make package-vmagent`. It builds `victoriametrics/vmagent:<PKG_TAG>` docker image locally.
 `<PKG_TAG>` is auto-generated image tag, which depends on source code in the repository.
 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 1.13.
+2. Run `make vmagent-arm` or `make vmagent-arm64` from the root folder of the repository.
+   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.
+   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. It can be collected with the following command:
+
+```bash
+curl -s http://<vmagent-host>:8429/debug/pprof/heap > mem.pprof
+```
+
+* CPU profile. It 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).

app/vmagent/csvimport/request_handler.go

@@ -0,0 +1,71 @@
+package csvimport
+
+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/csvimport"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted  = metrics.NewCounter(`vmagent_rows_inserted_total{type="csvimport"}`)
+	rowsPerInsert = metrics.NewHistogram(`vmagent_rows_per_insert{type="csvimport"}`)
+)
+
+// InsertHandler processes csv data from req.
+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/deployment/Dockerfile

@@ -1,8 +1,8 @@
-ARG certs_image
-FROM $certs_image AS certs
-FROM scratch
-COPY --from=certs /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
+ARG base_image
+FROM $base_image
+
+EXPOSE 8429
+
+ENTRYPOINT ["/vmagent-prod"]
 ARG src_binary
 COPY $src_binary ./vmagent-prod
-EXPOSE 8429
-ENTRYPOINT ["/vmagent-prod"]

app/vmagent/influx/request_handler.go

@@ -19,6 +19,7 @@ import (
 var (
 	measurementFieldSeparator = flag.String("influxMeasurementFieldSeparator", "_", "Separator for '{measurement}{separator}{field_name}' metric name when inserted via Influx line protocol")
 	skipSingleField           = flag.Bool("influxSkipSingleField", false, "Uses '{measurement}' instead of '{measurement}{separator}{field_name}' for metic name if Influx line contains only a single field")
+	skipMeasurement           = flag.Bool("influxSkipMeasurement", false, "Uses '{field_name}' as a metric name while ignoring '{measurement}' and '-influxMeasurementFieldSeparator'")
 )
 
 var (
@@ -61,25 +62,29 @@ func insertRows(db string, rows []parser.Row) error {
 	buf := ctx.buf[:0]
 	for i := range rows {
 		r := &rows[i]
+		rowsTotal += len(r.Fields)
 		commonLabels = commonLabels[:0]
-		hasDBLabel := false
+		hasDBKey := false
 		for j := range r.Tags {
 			tag := &r.Tags[j]
 			if tag.Key == "db" {
-				hasDBLabel = true
+				hasDBKey = true
 			}
 			commonLabels = append(commonLabels, prompbmarshal.Label{
 				Name:  tag.Key,
 				Value: tag.Value,
 			})
 		}
-		if len(db) > 0 && !hasDBLabel {
+		if len(db) > 0 && !hasDBKey {
 			commonLabels = append(commonLabels, prompbmarshal.Label{
 				Name:  "db",
 				Value: db,
 			})
 		}
-		ctx.metricGroupBuf = append(ctx.metricGroupBuf[:0], r.Measurement...)
+		ctx.metricGroupBuf = ctx.metricGroupBuf[:0]
+		if !*skipMeasurement {
+			ctx.metricGroupBuf = append(ctx.metricGroupBuf, r.Measurement...)
+		}
 		skipFieldKey := len(r.Fields) == 1 && *skipSingleField
 		if len(ctx.metricGroupBuf) > 0 && !skipFieldKey {
 			ctx.metricGroupBuf = append(ctx.metricGroupBuf, *measurementFieldSeparator...)
@@ -107,7 +112,6 @@ func insertRows(db string, rows []parser.Row) error {
 				Samples: samples[len(samples)-1:],
 			})
 		}
-		rowsTotal += len(r.Fields)
 	}
 	ctx.buf = buf
 	ctx.ctx.WriteRequest.Timeseries = tssDst

app/vmagent/main.go

@@ -4,17 +4,23 @@ import (
 	"flag"
 	"fmt"
 	"net/http"
+	"os"
+	"strconv"
 	"strings"
 	"time"
 
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/csvimport"
 	"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/buildinfo"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envflag"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	graphiteserver "github.com/VictoriaMetrics/VictoriaMetrics/lib/ingestserver/graphite"
@@ -24,6 +30,7 @@ import (
 	"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"
 )
@@ -32,12 +39,15 @@ 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 Influx line protocol data. Usually :8189 must be set. Doesn't work if empty")
+	influxListenAddr = flag.String("influxListenAddr", "", "TCP and UDP address to listen for Influx 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 . See also -promscrape.config.dryRun")
 )
 
 var (
@@ -48,12 +58,33 @@ var (
 )
 
 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()
+	cgroup.UpdateGOMAXPROCSToCPUQuota()
+
+	if *dryRun {
+		if err := flag.Set("promscrape.config.strictParse", "true"); err != nil {
+			logger.Panicf("BUG: cannot set promscrape.config.strictParse=true: %s", err)
+		}
+		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 Prometheus 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, influx.InsertHandlerForReader)
@@ -101,19 +132,24 @@ func main() {
 	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.RequestURI == "/" {
+		fmt.Fprintf(w, "vmagent - see docs at https://victoriametrics.github.io/vmagent.html")
+		return true
+	}
 	path := strings.Replace(r.URL.Path, "//", "/", -1)
 	switch path {
 	case "/api/v1/write":
 		prometheusWriteRequests.Inc()
 		if err := promremotewrite.InsertHandler(r); err != nil {
 			prometheusWriteErrors.Inc()
-			httpserver.Errorf(w, "error in %q: %s", r.URL.Path, err)
+			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
 			return true
 		}
 		w.WriteHeader(http.StatusNoContent)
@@ -122,7 +158,34 @@ func requestHandler(w http.ResponseWriter, r *http.Request) bool {
 		vmimportRequests.Inc()
 		if err := vmimport.InsertHandler(r); err != nil {
 			vmimportErrors.Inc()
-			httpserver.Errorf(w, "error in %q: %s", r.URL.Path, err)
+			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "/api/v1/import/csv":
+		csvimportRequests.Inc()
+		if err := csvimport.InsertHandler(r); err != nil {
+			csvimportErrors.Inc()
+			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "/api/v1/import/prometheus":
+		prometheusimportRequests.Inc()
+		if err := prometheusimport.InsertHandler(r); err != nil {
+			prometheusimportErrors.Inc()
+			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	case "/api/v1/import/native":
+		nativeimportRequests.Inc()
+		if err := native.InsertHandler(r); err != nil {
+			nativeimportErrors.Inc()
+			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
 			return true
 		}
 		w.WriteHeader(http.StatusNoContent)
@@ -131,7 +194,7 @@ func requestHandler(w http.ResponseWriter, r *http.Request) bool {
 		influxWriteRequests.Inc()
 		if err := influx.InsertHandlerForHTTP(r); err != nil {
 			influxWriteErrors.Inc()
-			httpserver.Errorf(w, "error in %q: %s", r.URL.Path, err)
+			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
 			return true
 		}
 		w.WriteHeader(http.StatusNoContent)
@@ -145,23 +208,59 @@ func requestHandler(w http.ResponseWriter, r *http.Request) bool {
 	case "/targets":
 		promscrapeTargetsRequests.Inc()
 		w.Header().Set("Content-Type", "text/plain")
-		promscrape.WriteHumanReadableTargetsStatus(w)
+		showOriginalLabels, _ := strconv.ParseBool(r.FormValue("show_original_labels"))
+		promscrape.WriteHumanReadableTargetsStatus(w, showOriginalLabels)
+		return true
+	case "/api/v1/targets":
+		promscrapeAPIV1TargetsRequests.Inc()
+		w.Header().Set("Content-Type", "application/json")
+		state := r.FormValue("state")
+		promscrape.WriteAPIV1Targets(w, state)
+		return true
+	case "/-/reload":
+		promscrapeConfigReloadRequests.Inc()
+		procutil.SelfSIGHUP()
+		w.WriteHeader(http.StatusOK)
 		return true
 	}
 	return false
 }
 
 var (
-	prometheusWriteRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/api/v1/write", protocol="prometheus"}`)
-	prometheusWriteErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/api/v1/write", protocol="prometheus"}`)
+	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="vm"}`)
-	vmimportErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/api/v1/import", protocol="vm"}`)
+	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="/write", protocol="influx"}`)
 	influxWriteErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/write", protocol="influx"}`)
 
 	influxQueryRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/query", protocol="influx"}`)
 
-	promscrapeTargetsRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/targets"}`)
+	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://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmagent/README.md .
+`
+
+	f := flag.CommandLine.Output()
+	fmt.Fprintf(f, "%s\n", s)
+	flag.PrintDefaults()
+}

app/vmagent/native/request_handler.go

@@ -0,0 +1,85 @@
+package native
+
+import (
+	"net/http"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
+	"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/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted  = metrics.NewCounter(`vmagent_rows_inserted_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(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(block, extraLabels)
+		})
+	})
+}
+
+func insertRows(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)
+	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.Push(&ctx.WriteRequest)
+	return nil
+}

app/vmagent/prometheusimport/request_handler.go

@@ -0,0 +1,76 @@
+package prometheusimport
+
+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/prometheus"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var (
+	rowsInserted  = metrics.NewCounter(`vmagent_rows_inserted_total{type="prometheus"}`)
+	rowsPerInsert = metrics.NewHistogram(`vmagent_rows_per_insert{type="prometheus"}`)
+)
+
+// InsertHandler processes `/api/v1/import/prometheus` request.
+func InsertHandler(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(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/promremotewrite/request_handler.go

@@ -35,6 +35,7 @@ func insertRows(timeseries []prompb.TimeSeries) error {
 	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]
@@ -55,7 +56,6 @@ func insertRows(timeseries []prompb.TimeSeries) error {
 			Labels:  labels[labelsLen:],
 			Samples: samples[samplesLen:],
 		})
-		rowsTotal += len(ts.Samples)
 	}
 	ctx.WriteRequest.Timeseries = tssDst
 	ctx.Labels = labels

app/vmagent/remotewrite/client.go

@@ -1,131 +1,122 @@
 package remotewrite
 
 import (
+	"bytes"
 	"crypto/tls"
-	"crypto/x509"
 	"encoding/base64"
 	"flag"
 	"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/netutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/persistentqueue"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promauth"
 	"github.com/VictoriaMetrics/metrics"
-	"github.com/valyala/fasthttp"
 )
 
 var (
 	sendTimeout = flag.Duration("remoteWrite.sendTimeout", time.Minute, "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 = 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")
+	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 = flag.String("remoteWrite.basicAuth.username", "", "Optional basic auth username to use for -remoteWrite.url")
-	basicAuthPassword = flag.String("remoteWrite.basicAuth.password", "", "Optional basic auth password to use for -remoteWrite.url")
-	bearerToken       = flag.String("remoteWrite.bearerToken", "", "Optional bearer auth token to use for -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")
+	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")
 )
 
 type client struct {
-	urlLabelValue  string
+	sanitizedURL   string
 	remoteWriteURL string
-	host           string
-	requestURI     string
 	authHeader     string
 	fq             *persistentqueue.FastQueue
-	hc             *fasthttp.HostClient
+	hc             *http.Client
 
 	requestDuration *metrics.Histogram
 	requestsOKCount *metrics.Counter
 	errorsCount     *metrics.Counter
+	packetsDropped  *metrics.Counter
 	retriesCount    *metrics.Counter
 
 	wg     sync.WaitGroup
 	stopCh chan struct{}
 }
 
-func newClient(remoteWriteURL, urlLabelValue string, fq *persistentqueue.FastQueue, concurrency int) *client {
+func newClient(argIdx int, remoteWriteURL, sanitizedURL string, fq *persistentqueue.FastQueue, concurrency int) *client {
+	tlsCfg, err := getTLSConfig(argIdx)
+	if err != nil {
+		logger.Panicf("FATAL: cannot initialize TLS config: %s", err)
+	}
+	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)
+	}
 	authHeader := ""
-	if len(*basicAuthUsername) > 0 || len(*basicAuthPassword) > 0 {
+	username := basicAuthUsername.GetOptionalArg(argIdx)
+	password := basicAuthPassword.GetOptionalArg(argIdx)
+	if len(username) > 0 || len(password) > 0 {
 		// See https://en.wikipedia.org/wiki/Basic_access_authentication
-		token := *basicAuthUsername + ":" + *basicAuthPassword
+		token := username + ":" + password
 		token64 := base64.StdEncoding.EncodeToString([]byte(token))
 		authHeader = "Basic " + token64
 	}
-	if len(*bearerToken) > 0 {
+	token := bearerToken.GetOptionalArg(argIdx)
+	if len(token) > 0 {
 		if authHeader != "" {
-			logger.Panicf("FATAL: `-remoteWrite.bearerToken`=%q cannot be set when `-remoteWrite.basicAuth.*` flags are set", *bearerToken)
+			logger.Fatalf("`-remoteWrite.bearerToken`=%q cannot be set when `-remoteWrite.basicAuth.*` flags are set", token)
 		}
-		authHeader = "Bearer " + *bearerToken
-	}
-
-	readTimeout := *sendTimeout
-	if readTimeout <= 0 {
-		readTimeout = time.Minute
-	}
-	var u fasthttp.URI
-	u.Update(remoteWriteURL)
-	scheme := string(u.Scheme())
-	switch scheme {
-	case "http", "https":
-	default:
-		logger.Panicf("FATAL: unsupported scheme in -remoteWrite.url=%q: %q. It must be http or https", remoteWriteURL, scheme)
-	}
-	host := string(u.Host())
-	if len(host) == 0 {
-		logger.Panicf("FATAL: invalid -remoteWrite.url=%q: host cannot be empty. Make sure the url looks like `http://host:port/path`", remoteWriteURL)
-	}
-	requestURI := string(u.RequestURI())
-	isTLS := scheme == "https"
-	var tlsCfg *tls.Config
-	if isTLS {
-		var err error
-		tlsCfg, err = getTLSConfig()
-		if err != nil {
-			logger.Panicf("FATAL: cannot initialize TLS config: %s", err)
-		}
-	}
-	if !strings.Contains(host, ":") {
-		if isTLS {
-			host += ":443"
-		} else {
-			host += ":80"
-		}
-	}
-	maxConns := 2 * concurrency
-	hc := &fasthttp.HostClient{
-		Addr:                host,
-		Name:                "vmagent",
-		Dial:                statDial,
-		DialDualStack:       netutil.TCP6Enabled(),
-		IsTLS:               isTLS,
-		TLSConfig:           tlsCfg,
-		MaxConns:            maxConns,
-		MaxIdleConnDuration: 10 * readTimeout,
-		ReadTimeout:         readTimeout,
-		WriteTimeout:        10 * time.Second,
-		MaxResponseBodySize: 1024 * 1024,
+		authHeader = "Bearer " + token
 	}
 	c := &client{
-		urlLabelValue:  urlLabelValue,
+		sanitizedURL:   sanitizedURL,
 		remoteWriteURL: remoteWriteURL,
-		host:           host,
-		requestURI:     requestURI,
 		authHeader:     authHeader,
 		fq:             fq,
-		hc:             hc,
-		stopCh:         make(chan struct{}),
+		hc: &http.Client{
+			Transport: tr,
+			Timeout:   *sendTimeout,
+		},
+		stopCh: make(chan struct{}),
 	}
-	c.requestDuration = metrics.GetOrCreateHistogram(fmt.Sprintf(`vmagent_remotewrite_duration_seconds{url=%q}`, c.urlLabelValue))
-	c.requestsOKCount = metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_requests_total{url=%q, status_code="2XX"}`, c.urlLabelValue))
-	c.errorsCount = metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_errors_total{url=%q}`, c.urlLabelValue))
-	c.retriesCount = metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_retries_count_total{url=%q}`, c.urlLabelValue))
+	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))
 	for i := 0; i < concurrency; i++ {
 		c.wg.Add(1)
 		go func() {
@@ -133,44 +124,32 @@ func newClient(remoteWriteURL, urlLabelValue string, fq *persistentqueue.FastQue
 			c.runWorker()
 		}()
 	}
-	logger.Infof("initialized client for -remoteWrite.url=%q", c.remoteWriteURL)
+	logger.Infof("initialized client for -remoteWrite.url=%q", c.sanitizedURL)
 	return c
 }
 
 func (c *client) MustStop() {
 	close(c.stopCh)
 	c.wg.Wait()
-	logger.Infof("stopped client for -remoteWrite.url=%q", c.remoteWriteURL)
+	logger.Infof("stopped client for -remoteWrite.url=%q", c.sanitizedURL)
 }
 
-func getTLSConfig() (*tls.Config, error) {
-	var tlsRootCA *x509.CertPool
-	var tlsCertificate *tls.Certificate
-	if *tlsCertFile != "" || *tlsKeyFile != "" {
-		cert, err := tls.LoadX509KeyPair(*tlsCertFile, *tlsKeyFile)
-		if err != nil {
-			return nil, fmt.Errorf("cannot load TLS certificate for -remoteWrite.tlsCertFile=%q and -remoteWrite.tlsKeyFile=%q: %s", *tlsCertFile, *tlsKeyFile, err)
-		}
-		tlsCertificate = &cert
+func getTLSConfig(argIdx int) (*tls.Config, error) {
+	c := &promauth.TLSConfig{
+		CAFile:             tlsCAFile.GetOptionalArg(argIdx),
+		CertFile:           tlsCertFile.GetOptionalArg(argIdx),
+		KeyFile:            tlsKeyFile.GetOptionalArg(argIdx),
+		ServerName:         tlsServerName.GetOptionalArg(argIdx),
+		InsecureSkipVerify: *tlsInsecureSkipVerify,
 	}
-	if *tlsCAFile != "" {
-		data, err := ioutil.ReadFile(*tlsCAFile)
-		if err != nil {
-			return nil, fmt.Errorf("cannot read -remoteWrite.tlsCAFile=%q: %s", *tlsCAFile, err)
-		}
-		tlsRootCA = x509.NewCertPool()
-		if !tlsRootCA.AppendCertsFromPEM(data) {
-			return nil, fmt.Errorf("cannot parse data -remoteWrite.tlsCAFile=%q", *tlsCAFile)
-		}
+	if c.CAFile == "" && c.CertFile == "" && c.KeyFile == "" && c.ServerName == "" && !c.InsecureSkipVerify {
+		return nil, nil
 	}
-	tlsCfg := &tls.Config{
-		RootCAs:            tlsRootCA,
-		ClientSessionCache: tls.NewLRUClientSessionCache(0),
+	cfg, err := promauth.NewConfig(".", nil, "", "", c)
+	if err != nil {
+		return nil, fmt.Errorf("cannot populate TLS config: %w", err)
 	}
-	if tlsCertificate != nil {
-		tlsCfg.Certificates = []tls.Certificate{*tlsCertificate}
-	}
-	tlsCfg.InsecureSkipVerify = *tlsInsecureSkipVerify
+	tlsCfg := cfg.NewTLSConfig()
 	return tlsCfg, nil
 }
 
@@ -199,7 +178,7 @@ func (c *client) runWorker() {
 				// The block has been sent successfully.
 			case <-time.After(graceDuration):
 				logger.Errorf("couldn't sent block with size %d bytes to %q in %.3f seconds during shutdown; dropping it",
-					len(block), c.remoteWriteURL, graceDuration.Seconds())
+					len(block), c.sanitizedURL, graceDuration.Seconds())
 			}
 			return
 		}
@@ -207,32 +186,25 @@ func (c *client) runWorker() {
 }
 
 func (c *client) sendBlock(block []byte) {
-	req := fasthttp.AcquireRequest()
-	req.SetRequestURI(c.requestURI)
-	req.SetHost(c.host)
-	req.Header.SetMethod("POST")
-	req.Header.Add("Content-Type", "application/x-protobuf")
-	req.Header.Add("Content-Encoding", "snappy")
+	retryDuration := time.Second
+	retriesCount := 0
+
+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 c.authHeader != "" {
 		req.Header.Set("Authorization", c.authHeader)
 	}
-	req.SetBody(block)
-
-	retryDuration := time.Second
-	resp := fasthttp.AcquireResponse()
-
-again:
-	select {
-	case <-c.stopCh:
-		fasthttp.ReleaseRequest(req)
-		fasthttp.ReleaseResponse(resp)
-		return
-	default:
-	}
 
 	startTime := time.Now()
-	// There is no need in calling DoTimeout, since the timeout is set in c.hc.ReadTimeout.
-	err := c.hc.Do(req, resp)
+	resp, err := c.hc.Do(req)
 	c.requestDuration.UpdateDuration(startTime)
 	if err != nil {
 		c.errorsCount.Inc()
@@ -241,27 +213,56 @@ again:
 			retryDuration = time.Minute
 		}
 		logger.Errorf("couldn't send a block with size %d bytes to %q: %s; re-sending the block in %.3f seconds",
-			len(block), c.remoteWriteURL, err, retryDuration.Seconds())
-		time.Sleep(retryDuration)
-		c.retriesCount.Inc()
-		goto again
-	}
-	statusCode := resp.StatusCode()
-	if statusCode/100 != 2 {
-		metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_requests_total{url=%q, status_code="%d"}`, c.urlLabelValue, statusCode)).Inc()
-		retryDuration *= 2
-		if retryDuration > time.Minute {
-			retryDuration = time.Minute
+			len(block), c.sanitizedURL, err, retryDuration.Seconds())
+		t := time.NewTimer(retryDuration)
+		select {
+		case <-c.stopCh:
+			t.Stop()
+			return
+		case <-t.C:
 		}
-		logger.Errorf("unexpected status code received after sending a block with size %d bytes to %q: %d; response body=%q; re-sending the block in %.3f seconds",
-			len(block), c.remoteWriteURL, statusCode, resp.Body(), retryDuration.Seconds())
-		time.Sleep(retryDuration)
 		c.retriesCount.Inc()
 		goto again
 	}
-	c.requestsOKCount.Inc()
+	statusCode := resp.StatusCode
+	if statusCode/100 == 2 {
+		_ = resp.Body.Close()
+		c.requestsOKCount.Inc()
+		return
+	}
+	metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_requests_total{url=%q, status_code="%d"}`, c.sanitizedURL, statusCode)).Inc()
+	if statusCode/100 == 4 {
+		// Just drop block on 4xx status code like Prometheus does.
+		// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/873
+		body, _ := ioutil.ReadAll(resp.Body)
+		_ = resp.Body.Close()
+		logger.Errorf("unexpected status code received when sending a block with size %d bytes to %q: #%d; dropping the block for 4XX status code like Prometheus does; "+
+			"response body=%q", len(block), c.sanitizedURL, statusCode, body)
+		c.packetsDropped.Inc()
+		return
+	}
 
-	// The block has been successfully sent to the remote storage.
-	fasthttp.ReleaseResponse(resp)
-	fasthttp.ReleaseRequest(req)
+	// 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 := time.NewTimer(retryDuration)
+	select {
+	case <-c.stopCh:
+		t.Stop()
+		return
+	case <-t.C:
+	}
+	c.retriesCount.Inc()
+	goto again
 }

app/vmagent/remotewrite/pendingseries.go

@@ -3,10 +3,12 @@ package remotewrite
 import (
 	"flag"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"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/metrics"
@@ -15,8 +17,9 @@ import (
 
 var (
 	flushInterval = flag.Duration("remoteWrite.flushInterval", time.Second, "Interval for flushing the data to remote storage. "+
-		"Higher value reduces network bandwidth usage at the cost of delayed push of scraped data to remote storage")
-	maxUnpackedBlockSize = flag.Int("remoteWrite.maxBlockSize", 32*1024*1024, "The maximum size in bytes of unpacked request to send to remote storage. "+
+		"Higher value reduces network bandwidth usage at the cost of delayed push of scraped data to remote storage. "+
+		"Minimum supported interval is 1 second")
+	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")
 )
 
@@ -55,6 +58,10 @@ func (ps *pendingSeries) Push(tss []prompbmarshal.TimeSeries) {
 }
 
 func (ps *pendingSeries) periodicFlusher() {
+	flushSeconds := int64(flushInterval.Seconds())
+	if flushSeconds <= 0 {
+		flushSeconds = 1
+	}
 	ticker := time.NewTicker(*flushInterval)
 	defer ticker.Stop()
 	mustStop := false
@@ -63,7 +70,7 @@ func (ps *pendingSeries) periodicFlusher() {
 		case <-ps.stopCh:
 			mustStop = true
 		case <-ticker.C:
-			if time.Since(ps.wr.lastFlushTime) < *flushInterval/2 {
+			if fasttime.UnixTimestamp()-atomic.LoadUint64(&ps.wr.lastFlushTime) < uint64(flushSeconds) {
 				continue
 			}
 		}
@@ -74,9 +81,11 @@ func (ps *pendingSeries) periodicFlusher() {
 }
 
 type writeRequest struct {
-	wr            prompbmarshal.WriteRequest
-	pushBlock     func(block []byte)
-	lastFlushTime time.Time
+	// Move lastFlushTime to the top of the struct in order to guarantee atomic access on 32-bit architectures.
+	lastFlushTime uint64
+
+	wr        prompbmarshal.WriteRequest
+	pushBlock func(block []byte)
 
 	tss []prompbmarshal.TimeSeries
 
@@ -108,7 +117,7 @@ func (wr *writeRequest) reset() {
 
 func (wr *writeRequest) flush() {
 	wr.wr.Timeseries = wr.tss
-	wr.lastFlushTime = time.Now()
+	atomic.StoreUint64(&wr.lastFlushTime, fasttime.UnixTimestamp())
 	pushWriteRequest(&wr.wr, wr.pushBlock)
 	wr.reset()
 }
@@ -117,9 +126,9 @@ func (wr *writeRequest) push(src []prompbmarshal.TimeSeries) {
 	tssDst := wr.tss
 	for i := range src {
 		tssDst = append(tssDst, prompbmarshal.TimeSeries{})
-		dst := &tssDst[len(tssDst)-1]
-		wr.copyTimeSeries(dst, &src[i])
-		if len(wr.tss) >= maxRowsPerBlock {
+		wr.copyTimeSeries(&tssDst[len(tssDst)-1], &src[i])
+		if len(wr.samples) >= maxRowsPerBlock {
+			wr.tss = tssDst
 			wr.flush()
 			tssDst = wr.tss
 		}
@@ -144,13 +153,8 @@ func (wr *writeRequest) copyTimeSeries(dst, src *prompbmarshal.TimeSeries) {
 	}
 	dst.Labels = labelsDst[labelsLen:]
 
-	samplesDst = append(samplesDst, prompbmarshal.Sample{})
-	dstSample := &samplesDst[len(samplesDst)-1]
-	if len(src.Samples) != 1 {
-		logger.Panicf("BUG: unexpected number of samples in time series; got %d; want 1", len(src.Samples))
-	}
-	*dstSample = src.Samples[0]
-	dst.Samples = samplesDst[len(samplesDst)-1:]
+	samplesDst = append(samplesDst, src.Samples...)
+	dst.Samples = samplesDst[len(samplesDst)-len(src.Samples):]
 
 	wr.samples = samplesDst
 	wr.labels = labelsDst
@@ -164,7 +168,7 @@ func pushWriteRequest(wr *prompbmarshal.WriteRequest, pushBlock func(block []byt
 	}
 	bb := writeRequestBufPool.Get()
 	bb.B = prompbmarshal.MarshalWriteRequest(bb.B[:0], wr)
-	if len(bb.B) <= *maxUnpackedBlockSize {
+	if len(bb.B) <= maxUnpackedBlockSize.N {
 		zb := snappyBufPool.Get()
 		zb.B = snappy.Encode(zb.B[:cap(zb.B)], bb.B)
 		writeRequestBufPool.Put(bb)

app/vmagent/remotewrite/relabel.go

@@ -2,6 +2,7 @@ package remotewrite
 
 import (
 	"flag"
+	"fmt"
 	"strings"
 	"sync"
 
@@ -15,36 +16,64 @@ 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 flags 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://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config for details")
+		"before sending them to -remoteWrite.url. See https://victoriametrics.github.io/vmagent.html#relabeling for details")
+	relabelConfigPaths = flagutil.NewArray("remoteWrite.urlRelabelConfig", "Optional path to relabel config for the corresponding -remoteWrite.url")
 )
 
 var labelsGlobal []prompbmarshal.Label
-var prcsGlobal []promrelabel.ParsedRelabelConfig
 
-// initRelabelGlobal must be called after parsing command-line flags.
-func initRelabelGlobal() {
-	// Init labelsGlobal
+// 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)
+		if err != nil {
+			return nil, fmt.Errorf("cannot load -remoteWrite.relabelConfig=%q: %w", *relabelConfigPathGlobal, err)
+		}
+		rcs.global = global
+	}
+	if len(*relabelConfigPaths) > len(*remoteWriteURLs) {
+		return nil, fmt.Errorf("too many -remoteWrite.urlRelabelConfig args: %d; it mustn't exceed the number of -remoteWrite.url args: %d",
+			len(*relabelConfigPaths), len(*remoteWriteURLs))
+	}
+	rcs.perURL = make([][]promrelabel.ParsedRelabelConfig, len(*remoteWriteURLs))
+	for i, path := range *relabelConfigPaths {
+		if len(path) == 0 {
+			// Skip empty relabel config.
+			continue
+		}
+		prc, err := promrelabel.LoadRelabelConfigs(path)
+		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.ParsedRelabelConfig
+	perURL [][]promrelabel.ParsedRelabelConfig
+}
+
+// initLabelsGlobal must be called after parsing command-line flags.
+func initLabelsGlobal() {
 	labelsGlobal = nil
 	for _, s := range *unparsedLabelsGlobal {
 		n := strings.IndexByte(s, '=')
 		if n < 0 {
-			logger.Panicf("FATAL: missing '=' in `-remoteWrite.label`. It must contain label in the form `name=value`; got %q", s)
+			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:],
 		})
 	}
-
-	// Init prcsGlobal
-	prcsGlobal = nil
-	if len(*relabelConfigPathGlobal) > 0 {
-		var err error
-		prcsGlobal, err = promrelabel.LoadRelabelConfigs(*relabelConfigPathGlobal)
-		if err != nil {
-			logger.Panicf("FATAL: cannot load relabel configs from -remoteWrite.relabelConfig=%q: %s", *relabelConfigPathGlobal, err)
-		}
-	}
 }
 
 func (rctx *relabelCtx) applyRelabeling(tss []prompbmarshal.TimeSeries, extraLabels []prompbmarshal.Label, prcs []promrelabel.ParsedRelabelConfig) []prompbmarshal.TimeSeries {

app/vmagent/remotewrite/remotewrite.go

@@ -3,15 +3,17 @@ package remotewrite
 import (
 	"flag"
 	"fmt"
+	"runtime"
+	"sync"
 	"sync/atomic"
 
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/decimal"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"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/metrics"
 	xxhash "github.com/cespare/xxhash/v2"
 )
@@ -20,20 +22,37 @@ 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 write data concurrently to multiple remote storage systems")
-	relabelConfigPaths = flagutil.NewArray("remoteWrite.urlRelabelConfig", "Optional path to relabel config for the corresponding -remoteWrite.url")
-	tmpDataPath        = flag.String("remoteWrite.tmpDataPath", "vmagent-remotewrite-data", "Path to directory where temporary data for remote write component is stored")
-	queues             = flag.Int("remoteWrite.queues", 1, "The number of concurrent queues to each -remoteWrite.url. Set more queues if a single queue "+
+	tmpDataPath = flag.String("remoteWrite.tmpDataPath", "vmagent-remotewrite-data", "Path to directory where temporary data for remote write component is stored")
+	queues      = flag.Int("remoteWrite.queues", 4, "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")
 	showRemoteWriteURL = flag.Bool("remoteWrite.showURL", false, "Whether to show -remoteWrite.url in the exported metrics. "+
-		"It is hidden by default, since it can contain sensistive auth info")
-	maxPendingBytesPerURL = flag.Int("remoteWrite.maxDiskUsagePerURL", 0, "The maximum file-based buffer size in bytes at -remoteWrite.tmpDataPath "+
+		"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 = flag.Int("remoteWrite.significantFigures", 0, "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 increasing on-disk compression level for the stored metrics")
 )
 
 var rwctxs []*remoteWriteCtx
 
+// 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 = runtime.GOMAXPROCS(-1) * 4
+
+// 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().
@@ -41,14 +60,20 @@ var rwctxs []*remoteWriteCtx
 // Stop must be called for graceful shutdown.
 func Init() {
 	if len(*remoteWriteURLs) == 0 {
-		logger.Panicf("FATAL: at least one `-remoteWrite.url` must be set")
+		logger.Fatalf("at least one `-remoteWrite.url` command-line flag must be set")
 	}
-
-	if !*showRemoteWriteURL {
-		// remoteWrite.url can contain authentication codes, so hide it at `/metrics` output.
-		httpserver.RegisterSecretFlag("remoteWrite.url")
+	if *queues > maxQueues {
+		*queues = maxQueues
 	}
-	initRelabelGlobal()
+	if *queues <= 0 {
+		*queues = 1
+	}
+	initLabelsGlobal()
+	rcs, err := loadRelabelConfigs()
+	if err != nil {
+		logger.Fatalf("cannot load relabel configs: %s", err)
+	}
+	allRelabelConfigs.Store(rcs)
 
 	maxInmemoryBlocks := memory.Allowed() / len(*remoteWriteURLs) / maxRowsPerBlock / 100
 	if maxInmemoryBlocks > 200 {
@@ -61,23 +86,47 @@ func Init() {
 		maxInmemoryBlocks = 2
 	}
 	for i, remoteWriteURL := range *remoteWriteURLs {
-		relabelConfigPath := ""
-		if i < len(*relabelConfigPaths) {
-			relabelConfigPath = (*relabelConfigPaths)[i]
-		}
-		urlLabelValue := fmt.Sprintf("secret-url-%d", i+1)
+		sanitizedURL := fmt.Sprintf("%d:secret-url", i+1)
 		if *showRemoteWriteURL {
-			urlLabelValue = remoteWriteURL
+			sanitizedURL = fmt.Sprintf("%d:%s", i+1, remoteWriteURL)
 		}
-		rwctx := newRemoteWriteCtx(remoteWriteURL, relabelConfigPath, maxInmemoryBlocks, urlLabelValue)
+		rwctx := newRemoteWriteCtx(i, remoteWriteURL, maxInmemoryBlocks, sanitizedURL)
 		rwctxs = append(rwctxs, rwctx)
 	}
+
+	// Start config reloader.
+	sighupCh := procutil.NewSighupChan()
+	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")
+		}
+	}()
 }
 
+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 rwctxs {
 		rwctx.MustStop()
 	}
@@ -86,19 +135,41 @@ func Stop() {
 
 // Push sends wr to remote storage systems set via `-remoteWrite.url`.
 //
-// Each timeseries in wr.Timeseries must contain one sample.
+// Note that wr may be modified by Push due to relabeling and rounding.
 func Push(wr *prompbmarshal.WriteRequest) {
+	if *significantFigures > 0 {
+		// Round values according to significantFigures
+		for i := range wr.Timeseries {
+			samples := wr.Timeseries[i].Samples
+			for j := range samples {
+				s := &samples[j]
+				s.Value = decimal.Round(s.Value, *significantFigures)
+			}
+		}
+	}
+
 	var rctx *relabelCtx
-	if len(prcsGlobal) > 0 {
+	rcs := allRelabelConfigs.Load().(*relabelConfigs)
+	prcsGlobal := rcs.global
+	if len(prcsGlobal) > 0 || len(labelsGlobal) > 0 {
 		rctx = getRelabelCtx()
 	}
 	tss := wr.Timeseries
 	for len(tss) > 0 {
-		// Process big tss in smaller blocks in order to reduce maxmimum memory usage
+		// Process big tss in smaller blocks in order to reduce the maximum memory usage
+		samplesCount := 0
+		i := 0
+		for i < len(tss) {
+			samplesCount += len(tss[i].Samples)
+			i++
+			if samplesCount > maxRowsPerBlock {
+				break
+			}
+		}
 		tssBlock := tss
-		if len(tssBlock) > maxRowsPerBlock {
-			tssBlock = tss[:maxRowsPerBlock]
-			tss = tss[maxRowsPerBlock:]
+		if i < len(tss) {
+			tssBlock = tss[:i]
+			tss = tss[i:]
 		} else {
 			tss = nil
 		}
@@ -122,45 +193,37 @@ func Push(wr *prompbmarshal.WriteRequest) {
 var globalRelabelMetricsDropped = metrics.NewCounter("vmagent_remotewrite_global_relabel_metrics_dropped_total")
 
 type remoteWriteCtx struct {
+	idx        int
 	fq         *persistentqueue.FastQueue
 	c          *client
-	prcs       []promrelabel.ParsedRelabelConfig
 	pss        []*pendingSeries
 	pssNextIdx uint64
 
 	relabelMetricsDropped *metrics.Counter
 }
 
-func newRemoteWriteCtx(remoteWriteURL, relabelConfigPath string, maxInmemoryBlocks int, urlLabelValue string) *remoteWriteCtx {
+func newRemoteWriteCtx(argIdx int, remoteWriteURL string, maxInmemoryBlocks int, sanitizedURL string) *remoteWriteCtx {
 	h := xxhash.Sum64([]byte(remoteWriteURL))
-	path := fmt.Sprintf("%s/persistent-queue/%016X", *tmpDataPath, h)
-	fq := persistentqueue.MustOpenFastQueue(path, remoteWriteURL, maxInmemoryBlocks, *maxPendingBytesPerURL)
-	_ = metrics.GetOrCreateGauge(fmt.Sprintf(`vmagent_remotewrite_pending_data_bytes{path=%q, url=%q}`, path, urlLabelValue), func() float64 {
+	path := fmt.Sprintf("%s/persistent-queue/%d_%016X", *tmpDataPath, argIdx+1, h)
+	fq := persistentqueue.MustOpenFastQueue(path, sanitizedURL, maxInmemoryBlocks, maxPendingBytesPerURL.N)
+	_ = metrics.GetOrCreateGauge(fmt.Sprintf(`vmagent_remotewrite_pending_data_bytes{path=%q, url=%q}`, path, sanitizedURL), func() float64 {
 		return float64(fq.GetPendingBytes())
 	})
-	_ = metrics.GetOrCreateGauge(fmt.Sprintf(`vmagent_remotewrite_pending_inmemory_blocks{path=%q, url=%q}`, path, urlLabelValue), func() float64 {
+	_ = metrics.GetOrCreateGauge(fmt.Sprintf(`vmagent_remotewrite_pending_inmemory_blocks{path=%q, url=%q}`, path, sanitizedURL), func() float64 {
 		return float64(fq.GetInmemoryQueueLen())
 	})
-	c := newClient(remoteWriteURL, urlLabelValue, fq, *queues)
-	var prcs []promrelabel.ParsedRelabelConfig
-	if len(relabelConfigPath) > 0 {
-		var err error
-		prcs, err = promrelabel.LoadRelabelConfigs(relabelConfigPath)
-		if err != nil {
-			logger.Panicf("FATAL: cannot load relabel configs from -remoteWrite.urlRelabelConfig=%q: %s", relabelConfigPath, err)
-		}
-	}
+	c := newClient(argIdx, remoteWriteURL, sanitizedURL, fq, *queues)
 	pss := make([]*pendingSeries, *queues)
 	for i := range pss {
 		pss[i] = newPendingSeries(fq.MustWriteBlock)
 	}
 	return &remoteWriteCtx{
-		fq:   fq,
-		c:    c,
-		prcs: prcs,
-		pss:  pss,
+		idx: argIdx,
+		fq:  fq,
+		c:   c,
+		pss: pss,
 
-		relabelMetricsDropped: metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_relabel_metrics_dropped_total{path=%q, url=%q}`, path, urlLabelValue)),
+		relabelMetricsDropped: metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_relabel_metrics_dropped_total{path=%q, url=%q}`, path, sanitizedURL)),
 	}
 }
 
@@ -168,10 +231,10 @@ func (rwctx *remoteWriteCtx) MustStop() {
 	for _, ps := range rwctx.pss {
 		ps.MustStop()
 	}
+	rwctx.idx = 0
 	rwctx.pss = nil
 	rwctx.fq.MustClose()
 	rwctx.fq = nil
-	rwctx.prcs = nil
 	rwctx.c.MustStop()
 	rwctx.c = nil
 
@@ -180,16 +243,34 @@ func (rwctx *remoteWriteCtx) MustStop() {
 
 func (rwctx *remoteWriteCtx) Push(tss []prompbmarshal.TimeSeries) {
 	var rctx *relabelCtx
-	if len(rwctx.prcs) > 0 {
+	var v *[]prompbmarshal.TimeSeries
+	rcs := allRelabelConfigs.Load().(*relabelConfigs)
+	prcs := rcs.perURL[rwctx.idx]
+	if len(prcs) > 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, rwctx.prcs)
+		tss = rctx.applyRelabeling(tss, nil, prcs)
 		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

@@ -1,15 +1,25 @@
 package remotewrite
 
 import (
+	"fmt"
 	"net"
+	"strings"
 	"sync/atomic"
 
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/netutil"
+	"github.com/VictoriaMetrics/fasthttp"
 	"github.com/VictoriaMetrics/metrics"
-	"github.com/valyala/fasthttp"
 )
 
-func statDial(addr string) (net.Conn, error) {
-	conn, err := fasthttp.Dial(addr)
+func statDial(network, addr string) (conn net.Conn, err error) {
+	if !strings.HasPrefix(network, "tcp") {
+		return nil, fmt.Errorf("unexpected network passed to statDial: %q; it must start from `tcp`", network)
+	}
+	if netutil.TCP6Enabled() {
+		conn, err = fasthttp.DialDualStack(addr)
+	} else {
+		conn, err = fasthttp.Dial(addr)
+	}
 	dialsTotal.Inc()
 	if err != nil {
 		dialErrors.Inc()

app/vmagent/vmimport/request_handler.go

@@ -6,7 +6,9 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
 	"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/writeconcurrencylimiter"
 	"github.com/VictoriaMetrics/metrics"
@@ -21,12 +23,18 @@ var (
 //
 // See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6
 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, insertRows)
+		return parser.ParseStream(req, func(rows []parser.Row) error {
+			return insertRows(rows, extraLabels)
+		})
 	})
 }
 
-func insertRows(rows []parser.Row) error {
+func insertRows(rows []parser.Row, extraLabels []prompbmarshal.Label) error {
 	ctx := common.GetPushCtx()
 	defer common.PutPushCtx(ctx)
 
@@ -36,6 +44,7 @@ func insertRows(rows []parser.Row) error {
 	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]
@@ -44,9 +53,12 @@ func insertRows(rows []parser.Row) error {
 				Value: bytesutil.ToUnsafeString(tag.Value),
 			})
 		}
+		labels = append(labels, extraLabels...)
 		values := r.Values
 		timestamps := r.Timestamps
-		_ = timestamps[len(values)-1]
+		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{
@@ -58,7 +70,6 @@ func insertRows(rows []parser.Row) error {
 			Labels:  labels[labelsLen:],
 			Samples: samples[samplesLen:],
 		})
-		rowsTotal += len(values)
 	}
 	ctx.WriteRequest.Timeseries = tssDst
 	ctx.Labels = labels

app/vmalert/Makefile

@@ -0,0 +1,90 @@
+# 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
+
+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
+
+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

app/vmalert/README.md

@@ -1,41 +1,379 @@
-## VM Alert
+## vmalert
 
-#### Abstract
-The application which accepts the alert rules, executes them on given source, sends(fires) an alert to(in) alert management system
+`vmalert` executes a list of 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.
 
-### Components
+### Features:
+* Integration with [VictoriaMetrics](https://github.com/VictoriaMetrics/VictoriaMetrics) TSDB;
+* VictoriaMetrics [MetricsQL](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/MetricsQL)
+ 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](https://github.com/VictoriaMetrics/VictoriaMetrics/tree/master/app/vmalert#alerts-state-on-restarts);
+* Lightweight without extra dependencies.
 
-#### Alert Config Reader
-It accepts yaml config as input parameter in Prometheus format, parses it into Go struct.
+### 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;
+* there is no `query` function support in templates yet;
+* `vmalert` has no UI, just an API for getting groups and rules statuses.
 
-#### Source Caller
-Create own watchdog for every alert group (goroutines), which executes alert query on given source and issues an alert if source returns non-empty result. 
-Source can be any service which supports PromQL (MetricsQL). 
+### QuickStart
 
-#### Alert Management System Provider
-Send positive alert to alert management system, provides interface for every concrete implementation.
-Should be ingratiated with Prometheus alertmanager. 
+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.
 
-open questions:
-- do we really need alert group or can just run every alert in own goroutine?
+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 - [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. This is optional.
 
-#### Web Server
-Expose metrics
+Then configure `vmalert` accordingly:
+```
+./bin/vmalert -rule=alert.rules \
+    -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 \  # PromQL 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
+    -evaluationInterval=3s                   # Default evaluation interval if not specified in rules group
+```
 
-open questions:
-- should the tool provide API or UI for managing alerting rules? Where to store config updated via the API or UI?
-- should the tool provide “alerting rules validation mode” for validating and debugging alerting rules? This mode is useful when creating and debugging alerting rules.
+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. 
 
-#### Requirements:
-- Stateless
-- Avoid external dependencies if possible
-- Reuse existing code from VictoriaMetrics repo
-- Makefile rules for common tasks – see Makefiles for other apps in the app/ dir 
-- Every package should be covered by tests 
-- Dockerfile
-- Graceful shutdown 
-- Helm template
-- Application uses command line flags for configuration
+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 `group` and every configuration file may contain arbitrary number of groups:
+```yaml
+groups:
+  [ - <rule_group> ]
+```
+
+#### Groups
+
+Each group has 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 = global.evaluation_interval ]
+
+# How many rules execute at once. Increasing concurrency may speed
+# up round execution speed. 
+[ concurrency: <integer> | default = 1 ]
+
+rules:
+  [ - <rule> ... ]
+```
+
+#### Rules
+
+There are two types of Rules:
+* [alerting](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/) - 
+Alerting rules allows to define alert conditions via [MetricsQL](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/MetricsQL)
+and to send notifications about firing alerts to [Alertmanager](https://github.com/prometheus/alertmanager).
+* [recording](https://prometheus.io/docs/prometheus/latest/configuration/recording_rules/) - 
+Recording rules allow you 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 following:
+```yaml
+# The name of the alert. Must be a valid metric name.
+alert: <string>
+
+# The MetricsQL expression to evaluate.
+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.
+[ 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> ]
+``` 
+
+##### 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>
+
+# The MetricsQL expression to evaluate.
+expr: <string>
+
+# Labels to add or overwrite before storing the result.
+labels:
+  [ <labelname>: <labelvalue> ]
+```
+
+For recording rules to work `-remoteWrite.url` must specified.
 
 
-<img alt="VM Alert" src="vmalert.png">
+#### Alerts state on restarts
+
+`vmalert` has no local storage, so alerts state is stored in the process memory. Hence, after reloading 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` or received state doesn't match current `vmalert` 
+rules configuration.
+
+
+#### WEB
+
+`vmalert` runs a web-server (`-httpListenAddr`) for serving metrics and alerts endpoints:
+* `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/<groupName>/<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.
+
+
+### Configuration
+
+The shortlist of configuration flags is the following:
+```
+  -datasource.basicAuth.password string
+    	Optional basic auth password for -datasource.url
+  -datasource.basicAuth.username string
+    	Optional basic auth username for -datasource.url
+  -datasource.lookback duration
+        Lookback defines how far to look into past when evaluating queries. For example, if 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 configured datasource.Consider to set this value equal to the value: groups_total * group.concurrency. Too low value may result into high number of sockets in TIME_WAIT state. (default 100)
+  -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
+    	Victoria Metrics or VMSelect url. Required parameter. E.g. http://127.0.0.1:8428
+  -enableTCP6
+    	Whether to enable IPv6 for listening and dialing. By default only IPv4 TCP 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
+  -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|pathEscape}}\"},{\"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 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
+  -http.connTimeout duration
+    	Incoming http connections are closed after the configured timeout. This may help spreading incoming load among a cluster of services behind load balancer. Note that the real timeout may be bigger by up to 10% as a protection from Thundering herd problem (default 2m0s)
+  -http.disableResponseCompression
+    	Disable compression of HTTP responses for saving 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 graceful shutdown of HTTP server. Highly loaded server may require increased value for 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 dealy the servier 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")
+  -loggerErrorsPerSecondLimit int
+    	Per-second limit on the number of ERROR messages. If more than the given number of errors are emitted per second, then the remaining errors are suppressed. Zero value disables the rate limit (default 10)
+  -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")
+  -memory.allowedBytes value
+    	Allowed size of system memory VictoriaMetrics caches may occupy. This option overrides -memory.allowedPercent if set to non-zero value. Too low value may increase cache miss rate, which usually results in higher CPU and disk IO usage. Too high value may evict too much data from OS page cache, which will result in higher disk IO usage
+    	Supports the following optional suffixes for 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 value may increase cache miss rate, which usually results in higher CPU and disk IO usage. Too high 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 -datasource.url
+    	Supports array of values separated by comma or specified via multiple flags.
+  -notifier.basicAuth.username array
+    	Optional basic auth username for -datasource.url
+    	Supports 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 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 array of values separated by comma or specified via multiple flags.
+  -notifier.tlsInsecureSkipVerify
+    	Whether to skip tls verification when connecting to -notifier.url
+  -notifier.tlsKeyFile array
+    	Optional path to client-side TLS certificate key to use when connecting to -notifier.url
+    	Supports 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 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 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.username string
+    	Optional basic auth username for -remoteRead.url
+  -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 Victoria Metrics 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.username string
+    	Optional basic auth username for -remoteWrite.url
+  -remoteWrite.concurrency int
+    	Defines number of writers for concurrent writing into remote querier (default 1)
+  -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 Victoria Metrics or VMInsert where to persist alerts state and recording rules results in form of timeseries. E.g. http://127.0.0.1:8428
+  -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 array of values separated by comma or specified via multiple flags.
+  -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, since RSA certs are slow
+  -tlsKeyFile string
+    	Path to file with TLS key. Used only if -tls is set
+  -version
+    	Show VictoriaMetrics version
+```
+
+Pass `-help` to `vmalert` in order to see the full list of supported 
+command-line flags with their descriptions.
+
+To reload configuration without `vmalert` restart send SIGHUP signal
+or send GET request to `/-/reload` endpoint.
+
+### 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 1.13.
+2. Run `make vmalert` from the root folder of the repository.
+   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.
+   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 1.13.
+2. Run `make vmalert-arm` or `make vmalert-arm64` from the root folder of the repository.
+   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.
+   It builds `vmalert-arm-prod` or `vmalert-arm64-prod` binary respectively and puts it into the `bin` folder.

app/vmalert/alerting.go

@@ -0,0 +1,445 @@
+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 {
+	RuleID      uint64
+	Name        string
+	Expr        string
+	For         time.Duration
+	Labels      map[string]string
+	Annotations map[string]string
+	GroupID     uint64
+	GroupName   string
+
+	// 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
+
+	metrics *alertingRuleMetrics
+}
+
+type alertingRuleMetrics struct {
+	errors  *gauge
+	pending *gauge
+	active  *gauge
+}
+
+func newAlertingRule(group *Group, cfg config.Rule) *AlertingRule {
+	ar := &AlertingRule{
+		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,
+		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.Lock()
+			defer ar.mu.Unlock()
+			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.Lock()
+			defer ar.mu.Unlock()
+			var num int
+			for _, a := range ar.alerts {
+				if a.State == notifier.StateFiring {
+					num++
+				}
+			}
+			return float64(num)
+		})
+	ar.metrics.errors = getOrCreateGauge(fmt.Sprintf(`vmalert_alerts_error{%s}`, labels),
+		func() float64 {
+			ar.mu.Lock()
+			defer ar.mu.Unlock()
+			if ar.lastExecError == nil {
+				return 0
+			}
+			return 1
+		})
+	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)
+}
+
+// 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
+}
+
+// Exec executes AlertingRule expression via the given Querier.
+// Based on the Querier results AlertingRule maintains notifier.Alerts
+func (ar *AlertingRule) Exec(ctx context.Context, q datasource.Querier, series bool) ([]prompbmarshal.TimeSeries, error) {
+	qMetrics, err := q.Query(ctx, ar.Expr)
+	ar.mu.Lock()
+	defer ar.mu.Unlock()
+
+	ar.lastExecError = err
+	ar.lastExecTime = time.Now()
+	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)
+		}
+	}
+
+	updated := make(map[uint64]struct{})
+	// update list of active alerts
+	for _, m := range qMetrics {
+		h := hash(m)
+		updated[h] = struct{}{}
+		if a, ok := ar.alerts[h]; ok {
+			if a.Value != m.Value {
+				// update Value field with latest value
+				a.Value = m.Value
+				// and re-exec template since Value can be used
+				// in templates
+				err = ar.template(a)
+				if err != nil {
+					return nil, err
+				}
+			}
+			continue
+		}
+		a, err := ar.newAlert(m, ar.lastExecTime)
+		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()
+		}
+	}
+	if series {
+		return ar.toTimeSeries(ar.lastExecTime), nil
+	}
+	return nil, nil
+}
+
+func (ar *AlertingRule) toTimeSeries(timestamp time.Time) []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
+	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) (*notifier.Alert, error) {
+	a := &notifier.Alert{
+		GroupID: ar.GroupID,
+		Name:    ar.Name,
+		Labels:  map[string]string{},
+		Value:   m.Value,
+		Start:   start,
+		Expr:    ar.Expr,
+	}
+	// label defined here to make override possible by
+	// time series labels.
+	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
+	}
+	return a, ar.template(a)
+}
+
+func (ar *AlertingRule) template(a *notifier.Alert) error {
+	// 1. template rule labels with data labels
+	rLabels, err := a.ExecTemplate(ar.Labels)
+	if err != nil {
+		return err
+	}
+
+	// 2. merge data labels and rule labels
+	// metric labels may be overridden by
+	// rule labels
+	for k, v := range rLabels {
+		a.Labels[k] = v
+	}
+
+	// 3. template merged labels
+	a.Labels, err = a.ExecTemplate(a.Labels)
+	if err != nil {
+		return err
+	}
+
+	a.Annotations, err = a.ExecTemplate(ar.Annotations)
+	return 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),
+		Name:        ar.Name,
+		Expression:  ar.Expr,
+		For:         ar.For.String(),
+		LastError:   lastErr,
+		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),
+
+		Name:        a.Name,
+		Expression:  ar.Expr,
+		Labels:      a.Labels,
+		Annotations: a.Annotations,
+		State:       a.State.String(),
+		ActiveAt:    a.Start,
+		Value:       strconv.FormatFloat(a.Value, 'e', -1, 64),
+	}
+}
+
+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 time.Time) []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 time.Time) 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(1, labels, timestamp)
+}
+
+// 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 time.Time) 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(a.Start.Unix()), labels, timestamp)
+}
+
+// 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")
+	}
+
+	// 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 {
+				continue
+			}
+			if l.Name == alertGroupNameLabel {
+				continue
+			}
+			// drop all overridden labels
+			if _, ok := ar.Labels[l.Name]; ok {
+				continue
+			}
+			m.Labels = append(m.Labels, l)
+		}
+
+		a, err := ar.newAlert(m, time.Unix(int64(m.Value), 0))
+		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 +1,456 @@
+package main
+
+import (
+	"context"
+	"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(1, map[string]string{
+					"__name__":      alertMetricName,
+					alertStateLabel: notifier.StateFiring.String(),
+					alertNameLabel:  "instant",
+				}, timestamp),
+			},
+		},
+		{
+			newTestAlertingRule("instant extra labels", 0),
+			&notifier.Alert{State: notifier.StateFiring, Labels: map[string]string{
+				"job":      "foo",
+				"instance": "bar",
+			}},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries(1, map[string]string{
+					"__name__":      alertMetricName,
+					alertStateLabel: notifier.StateFiring.String(),
+					alertNameLabel:  "instant extra labels",
+					"job":           "foo",
+					"instance":      "bar",
+				}, timestamp),
+			},
+		},
+		{
+			newTestAlertingRule("instant labels override", 0),
+			&notifier.Alert{State: notifier.StateFiring, Labels: map[string]string{
+				alertStateLabel: "foo",
+				"__name__":      "bar",
+			}},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries(1, map[string]string{
+					"__name__":      alertMetricName,
+					alertStateLabel: notifier.StateFiring.String(),
+					alertNameLabel:  "instant labels override",
+				}, timestamp),
+			},
+		},
+		{
+			newTestAlertingRule("for", time.Second),
+			&notifier.Alert{State: notifier.StateFiring, Start: timestamp.Add(time.Second)},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries(1, map[string]string{
+					"__name__":      alertMetricName,
+					alertStateLabel: notifier.StateFiring.String(),
+					alertNameLabel:  "for",
+				}, timestamp),
+				newTimeSeries(float64(timestamp.Add(time.Second).Unix()), map[string]string{
+					"__name__":     alertForStateMetricName,
+					alertNameLabel: "for",
+				}, timestamp),
+			},
+		},
+		{
+			newTestAlertingRule("for pending", 10*time.Second),
+			&notifier.Alert{State: notifier.StatePending, Start: timestamp.Add(time.Second)},
+			[]prompbmarshal.TimeSeries{
+				newTimeSeries(1, map[string]string{
+					"__name__":      alertMetricName,
+					alertStateLabel: notifier.StatePending.String(),
+					alertNameLabel:  "for pending",
+				}, timestamp),
+				newTimeSeries(float64(timestamp.Add(time.Second).Unix()), map[string]string{
+					"__name__":     alertForStateMetricName,
+					alertNameLabel: "for pending",
+				}, timestamp),
+			},
+		},
+	}
+	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)
+			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{}},
+			},
+			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("duplicate", 0),
+			[][]datasource.Metric{
+				{
+					// metrics with the same labelset should result in one alert
+					metricWithLabels(t, "name", "foo", "type", "bar"),
+					metricWithLabels(t, "type", "bar", "name", "foo"),
+				},
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t, "name", "foo", "type", "bar")): {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.GroupID = fakeGroup.ID()
+			for _, step := range tc.steps {
+				fq.reset()
+				fq.add(step...)
+				if _, err := tc.rule.Exec(context.TODO(), fq, false); 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_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",
+					// following pair supposed to be dropped
+					"source", "vm",
+				),
+			},
+			map[uint64]*notifier.Alert{
+				hash(metricWithLabels(t,
+					"foo", "bar",
+					"namespace", "baz",
+				)): {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()
+			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 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}
+}

app/vmalert/config/config.go

@@ -0,0 +1,271 @@
+package config
+
+import (
+	"crypto/md5"
+	"fmt"
+	"hash/fnv"
+	"io/ioutil"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+
+	"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"
+	"github.com/VictoriaMetrics/metricsql"
+	"gopkg.in/yaml.v2"
+)
+
+// Group contains list of Rules grouped into
+// entity with one name and evaluation interval
+type Group struct {
+	File        string
+	Name        string        `yaml:"name"`
+	Interval    time.Duration `yaml:"interval,omitempty"`
+	Rules       []Rule        `yaml:"rules"`
+	Concurrency int           `yaml:"concurrency"`
+	// 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)
+	}
+	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 {
+			if _, err := metricsql.Parse(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
+	Record      string            `yaml:"record,omitempty"`
+	Alert       string            `yaml:"alert,omitempty"`
+	Expr        string            `yaml:"expr"`
+	For         PromDuration      `yaml:"for,omitempty"`
+	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"`
+}
+
+// PromDuration is Prometheus duration.
+type PromDuration struct {
+	milliseconds int64
+}
+
+// NewPromDuration returns PromDuration for given d.
+func NewPromDuration(d time.Duration) PromDuration {
+	return PromDuration{
+		milliseconds: d.Milliseconds(),
+	}
+}
+
+// UnmarshalYAML implements yaml.Unmarshaler interface.
+func (pd *PromDuration) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var s string
+	if err := unmarshal(&s); err != nil {
+		return err
+	}
+	ms, err := metricsql.DurationValue(s, 0)
+	if err != nil {
+		return err
+	}
+	pd.milliseconds = ms
+	return nil
+}
+
+// Duration returns duration for pd.
+func (pd *PromDuration) Duration() time.Duration {
+	return time.Duration(pd.milliseconds) * time.Millisecond
+}
+
+// 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))
+	}
+	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 +1,356 @@
+package config
+
+import (
+	"net/url"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+	"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 \"value\" 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",
+		},
+	}
+	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": "{{ value|query }}",
+						},
+					},
+				},
+			},
+			expErr:              "error parsing annotation",
+			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: "",
+		},
+	}
+	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: 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) {
+	data := `
+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)
+`
+	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")
+	}
+	newData := `
+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)
+`
+	var ng Group
+	if err := yaml.Unmarshal([]byte(newData), &g); err != nil {
+		t.Fatalf("failed to unmarshal: %s", err)
+	}
+	if g.Checksum == ng.Checksum {
+		t.Fatalf("expected to get different checksums")
+	}
+}

app/vmalert/config/parser.go

@@ -1,32 +0,0 @@
-package config
-
-import "time"
-
-// Annotations basic annotation for alert rule
-type Annotations struct {
-	Summary     string
-	Description string
-}
-
-// Alert basic alert entity rule
-type Alert struct {
-	Name        string
-	Expr        string
-	For         time.Duration
-	Labels      map[string]string
-	Annotations Annotations
-
-	Start time.Time
-	End   time.Time
-}
-
-// Group grouping array of alert
-type Group struct {
-	Name  string
-	Rules []Alert
-}
-
-// Parse parses config from given file
-func Parse(filepath string) ([]Group, error) {
-	return []Group{}, nil
-}

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 +1,11 @@
+groups:
+  - name: duplicatedGroupDiffFiles
+    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: "{{ value|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/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-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 +1,35 @@
+groups:
+  - name: TestGroup
+    interval: 2s
+    concurrency: 2
+    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: ExampleAlertAlwaysFiring
+        expr: sum by(job)
+          (up == 1)
+      - 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/datasource/datasource.go

@@ -2,13 +2,23 @@ package datasource
 
 import "context"
 
-// Metrics the data returns from storage
-type Metrics struct{}
-
-// VMStorage represents vmstorage entity with ability to read and write metrics
-type VMStorage struct{}
-
-//Query basic query to the datasource
-func (s *VMStorage) Query(ctx context.Context, query string) ([]Metrics, error) {
-	return nil, nil
+// Querier interface wraps Query method which
+// executes given query and returns list of Metrics
+// as result
+type Querier interface {
+	Query(ctx context.Context, query string) ([]Metric, error)
+}
+
+// Metric is the basic entity which should be return by datasource
+// It represents single data point with full list of labels
+type Metric struct {
+	Labels    []Label
+	Timestamp int64
+	Value     float64
+}
+
+// Label represents metric's label
+type Label struct {
+	Name  string
+	Value string
 }

app/vmalert/datasource/init.go

@@ -0,0 +1,43 @@
+package datasource
+
+import (
+	"flag"
+	"fmt"
+	"net/http"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+)
+
+var (
+	addr = flag.String("datasource.url", "", "Victoria Metrics or VMSelect url. Required parameter."+
+		" E.g. http://127.0.0.1:8428")
+	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")
+
+	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 to look into past when evaluating queries. "+
+		"For example, if datasource.lookback=5m then param \"time\" with value now()-5m will be added to every query.")
+	maxIdleConnections = flag.Int("datasource.maxIdleConnections", 100, "Defines the number of idle (keep-alive connections) to configured datasource."+
+		"Consider to set this value equal to the value: groups_total * group.concurrency. Too low value may result into high number of sockets in TIME_WAIT state.")
+)
+
+// Init creates a Querier from provided flag values.
+func Init() (Querier, 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.MaxIdleConns = *maxIdleConnections
+	c := &http.Client{Transport: tr}
+	return NewVMStorage(*addr, *basicAuthUsername, *basicAuthPassword, *lookBack, c), nil
+}

app/vmalert/datasource/vm.go

@@ -0,0 +1,112 @@
+package datasource
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type response struct {
+	Status string `json:"status"`
+	Data   struct {
+		ResultType string `json:"resultType"`
+		Result     []struct {
+			Labels map[string]string `json:"metric"`
+			TV     [2]interface{}    `json:"value"`
+		} `json:"result"`
+	} `json:"data"`
+	ErrorType string `json:"errorType"`
+	Error     string `json:"error"`
+}
+
+func (r response) metrics() ([]Metric, error) {
+	var ms []Metric
+	var m Metric
+	var f float64
+	var err error
+	for i, res := range r.Data.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)
+		}
+		m.Labels = nil
+		for k, v := range r.Data.Result[i].Labels {
+			m.Labels = append(m.Labels, Label{Name: k, Value: v})
+		}
+		m.Timestamp = int64(res.TV[0].(float64))
+		m.Value = f
+		ms = append(ms, m)
+	}
+	return ms, nil
+}
+
+// VMStorage represents vmstorage entity with ability to read and write metrics
+type VMStorage struct {
+	c             *http.Client
+	queryURL      string
+	basicAuthUser string
+	basicAuthPass string
+	lookBack      time.Duration
+}
+
+const queryPath = "/api/v1/query?query="
+
+// NewVMStorage is a constructor for VMStorage
+func NewVMStorage(baseURL, basicAuthUser, basicAuthPass string, lookBack time.Duration, c *http.Client) *VMStorage {
+	return &VMStorage{
+		c:             c,
+		basicAuthUser: basicAuthUser,
+		basicAuthPass: basicAuthPass,
+		queryURL:      strings.TrimSuffix(baseURL, "/") + queryPath,
+		lookBack:      lookBack,
+	}
+}
+
+// Query reads metrics from datasource by given query
+func (s *VMStorage) Query(ctx context.Context, query string) ([]Metric, error) {
+	const (
+		statusSuccess, statusError, rtVector = "success", "error", "vector"
+	)
+	q := s.queryURL + url.QueryEscape(query)
+	if s.lookBack > 0 {
+		lookBack := time.Now().Add(-s.lookBack)
+		q += fmt.Sprintf("&time=%d", lookBack.Unix())
+	}
+	req, err := http.NewRequest("POST", q, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	if s.basicAuthPass != "" {
+		req.SetBasicAuth(s.basicAuthUser, s.basicAuthPass)
+	}
+	resp, err := s.c.Do(req.WithContext(ctx))
+	if err != nil {
+		return nil, fmt.Errorf("error getting response from %s: %w", req.URL, err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+	if resp.StatusCode != http.StatusOK {
+		body, _ := ioutil.ReadAll(resp.Body)
+		return nil, fmt.Errorf("datasource returns unexpected response code %d for %s. Response body %s", resp.StatusCode, req.URL, body)
+	}
+	r := &response{}
+	if err := json.NewDecoder(resp.Body).Decode(r); err != nil {
+		return nil, fmt.Errorf("error parsing 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)
+	}
+	if r.Data.ResultType != rtVector {
+		return nil, fmt.Errorf("unknown result type:%s. Expected vector", r.Data.ResultType)
+	}
+	return r.metrics()
+}

app/vmalert/datasource/vm_test.go

@@ -0,0 +1,101 @@
+package datasource
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"testing"
+	"time"
+)
+
+var (
+	ctx           = context.Background()
+	basicAuthName = "foo"
+	basicAuthPass = "bar"
+	query         = "vm_rows"
+)
+
+func TestVMSelectQuery(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", 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"]}]}}`))
+		}
+	})
+
+	srv := httptest.NewServer(mux)
+	defer srv.Close()
+	am := NewVMStorage(srv.URL, basicAuthName, basicAuthPass, time.Minute, srv.Client())
+	if _, err := am.Query(ctx, query); err == nil {
+		t.Fatalf("expected connection error got nil")
+	}
+	if _, err := am.Query(ctx, query); err == nil {
+		t.Fatalf("expected invalid response status error got nil")
+	}
+	if _, err := am.Query(ctx, query); err == nil {
+		t.Fatalf("expected response body error got nil")
+	}
+	if _, err := am.Query(ctx, query); err == nil {
+		t.Fatalf("expected error status got nil")
+	}
+	if _, err := am.Query(ctx, query); err == nil {
+		t.Fatalf("expected unknown status got nil")
+	}
+	if _, err := am.Query(ctx, query); err == nil {
+		t.Fatalf("expected non-vector resultType error  got nil")
+	}
+	m, err := am.Query(ctx, query)
+	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__"}},
+		Timestamp: 1583786142,
+		Value:     13763,
+	}
+	if m[0].Timestamp != expected.Timestamp &&
+		m[0].Value != expected.Value &&
+		m[0].Labels[0].Value != expected.Labels[0].Value &&
+		m[0].Labels[0].Name != expected.Labels[0].Name {
+		t.Fatalf("unexpected metric %+v want %+v", m[0], expected)
+	}
+}

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 +1,357 @@
+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
+	Interval    time.Duration
+	Concurrency int
+	Checksum    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
+}
+
+func newGroup(cfg config.Group, defaultInterval time.Duration, labels map[string]string) *Group {
+	g := &Group{
+		Name:        cfg.Name,
+		File:        cfg.File,
+		Interval:    cfg.Interval,
+		Concurrency: cfg.Concurrency,
+		Checksum:    cfg.Checksum,
+		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 {
+		// override rule labels with external labels
+		for k, v := range labels {
+			if prevV, ok := r.Labels[k]; ok {
+				logger.Infof("label %q=%q for rule %q.%q overwritten with external label %q=%q",
+					k, prevV, g.Name, r.Name(), k, v)
+			}
+			if r.Labels == nil {
+				r.Labels = map[string]string{}
+			}
+			r.Labels[k] = v
+		}
+		rules[i] = g.newRule(r)
+	}
+	g.Rules = rules
+	return g
+}
+
+func (g *Group) newRule(rule config.Rule) Rule {
+	if rule.Alert != "" {
+		return newAlertingRule(g, rule)
+	}
+	return newRecordingRule(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))
+	return hash.Sum64()
+}
+
+// Restore restores alerts state for group rules
+func (g *Group) Restore(ctx context.Context, q datasource.Querier, lookback time.Duration, labels map[string]string) error {
+	for _, rule := range g.Rules {
+		rr, ok := rule.(*AlertingRule)
+		if !ok {
+			continue
+		}
+		if rr.For < 1 {
+			continue
+		}
+		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)
+	}
+	g.Concurrency = newGroup.Concurrency
+	g.Checksum = newGroup.Checksum
+	g.Rules = newRules
+	return nil
+}
+
+var (
+	alertsFired      = metrics.NewCounter(`vmalert_alerts_fired_total`)
+	alertsSent       = metrics.NewCounter(`vmalert_alerts_sent_total`)
+	alertsSendErrors = metrics.NewCounter(`vmalert_alerts_send_errors_total`)
+)
+
+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, querier datasource.Querier, 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{querier, nts, rw}
+	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()
+
+			errs := e.execConcurrently(ctx, g.Rules, g.Concurrency, g.Interval)
+			for err := range errs {
+				if err != nil {
+					logger.Errorf("group %q: %s", g.Name, err)
+				}
+			}
+
+			g.metrics.iterationDuration.UpdateDuration(iterationStart)
+		}
+	}
+}
+
+type executor struct {
+	querier   datasource.Querier
+	notifiers []notifier.Notifier
+	rw        *remotewrite.Client
+}
+
+func (e *executor) execConcurrently(ctx context.Context, rules []Rule, concurrency int, interval time.Duration) chan error {
+	res := make(chan error, len(rules))
+	var returnSeries bool
+	if e.rw != nil {
+		returnSeries = true
+	}
+
+	if concurrency == 1 {
+		// fast path
+		for _, rule := range rules {
+			res <- e.exec(ctx, rule, returnSeries, interval)
+		}
+		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, returnSeries, interval)
+				<-sem
+				wg.Done()
+			}(rule)
+		}
+		wg.Wait()
+		close(res)
+	}()
+	return res
+}
+
+var (
+	execTotal    = metrics.NewCounter(`vmalert_execution_total`)
+	execErrors   = metrics.NewCounter(`vmalert_execution_errors_total`)
+	execDuration = metrics.NewSummary(`vmalert_execution_duration_seconds`)
+
+	remoteWriteErrors = metrics.NewCounter(`vmalert_remotewrite_errors_total`)
+)
+
+func (e *executor) exec(ctx context.Context, rule Rule, returnSeries bool, interval time.Duration) error {
+	execTotal.Inc()
+	execStart := time.Now()
+	defer func() {
+		execDuration.UpdateDuration(execStart)
+	}()
+
+	tss, err := rule.Exec(ctx, e.querier, returnSeries)
+	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:
+			// set End to execStart + 3 intervals
+			// so notifier can resolve it automatically if `vmalert`
+			// won't be able to send resolve for some reason
+			a.End = time.Now().Add(3 * interval)
+			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
+	}
+
+	alertsSent.Add(len(alerts))
+	errGr := new(utils.ErrGroup)
+	for _, nt := range e.notifiers {
+		if err := nt.Send(ctx, alerts); err != nil {
+			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 +1,213 @@
+package main
+
+import (
+	"context"
+	"sort"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+)
+
+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:   config.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:   config.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"},
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			g := &Group{Name: "test"}
+			for _, r := range tc.currentRules {
+				r.ID = config.HashRule(r)
+				g.Rules = append(g.Rules, g.newRule(r))
+			}
+
+			ng := &Group{Name: "test"}
+			for _, r := range tc.newRules {
+				r.ID = config.HashRule(r)
+				ng.Rules = append(ng.Rules, ng.newRule(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
+	g := newGroup(groups[0], evalInterval, map[string]string{"cluster": "east-1"})
+	g.Concurrency = 2
+
+	fn := &fakeNotifier{}
+	fs := &fakeQuerier{}
+
+	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())
+	if err != nil {
+		t.Fatalf("faield to create alert: %s", err)
+	}
+	alert1.State = notifier.StateFiring
+	alert1.ID = hash(m1)
+
+	alert2, err := r.newAlert(m2, time.Now())
+	if err != nil {
+		t.Fatalf("faield to create alert: %s", err)
+	}
+	alert2.State = notifier.StateFiring
+	alert2.ID = hash(m2)
+
+	finished := make(chan struct{})
+	fs.add(m1)
+	fs.add(m2)
+	go func() {
+		g.start(context.Background(), fs, []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
+}

app/vmalert/helpers_test.go

@@ -0,0 +1,232 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"sort"
+	"sync"
+	"testing"
+
+	"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) 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 (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 {
+	t.Helper()
+	m := metricWithLabels(t, labels...)
+	m.Value = value
+	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{}
+	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)
+	}
+	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

@@ -1,60 +1,226 @@
 package main
 
 import (
+	"context"
 	"flag"
-	"net/http"
+	"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/cgroup"
 	"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 (
-	configPath     = flag.String("config", "config.yaml", "Path to alert configuration file")
-	httpListenAddr = flag.String("httpListenAddr", ":8880", "Address to listen for http connections")
+	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.`)
+
+	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")
+	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|pathEscape}}\"},{\"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.")
+
+	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()
+	cgroup.UpdateGOMAXPROCSToCPUQuota()
 
-	logger.Infof("reading alert rules configuration file from %s", *configPath)
-	alertGroups, err := config.Parse(*configPath)
+	if *dryRun {
+		u, _ := url.Parse("https://victoriametrics.com/")
+		notifier.InitTemplateFunc(u)
+		groups, err := config.Parse(*rulePath, true, true)
+		if err != nil {
+			logger.Fatalf(err.Error())
+		}
+		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
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	manager, err := newManager(ctx)
 	if err != nil {
-		logger.Fatalf("Cannot parse configuration file %s", err)
+		logger.Fatalf("failed to init: %s", err)
 	}
-	w := &watchdog{storage: &datasource.VMStorage{}}
-	for id := range alertGroups {
-		go func(group config.Group) {
-			w.run(group)
-		}(alertGroups[id])
+	if err := manager.start(ctx, *rulePath, *validateTemplates, *validateExpressions); err != nil {
+		logger.Fatalf("failed to start: %s", err)
 	}
+
 	go func() {
-		httpserver.Serve(*httpListenAddr, func(w http.ResponseWriter, r *http.Request) bool {
-			panic("not implemented")
-		})
+		// init reload metrics with positive values to improve alerting conditions
+		configSuccess.Set(1)
+		configTimestamp.Set(fasttime.UnixTimestamp())
+		sigHup := procutil.NewSighupChan()
+		for {
+			<-sigHup
+			configReloads.Inc()
+			logger.Infof("SIGHUP received. Going to reload rules %q ...", *rulePath)
+			if err := manager.update(ctx, *rulePath, *validateTemplates, *validateExpressions, 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)
+		}
 	}()
+
+	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)
 	}
-	w.stop()
+	cancel()
+	manager.close()
 }
 
-type watchdog struct {
-	storage *datasource.VMStorage
+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()
+	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),
+		querier:   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 {
+		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 (w *watchdog) run(a config.Group) {
-
+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 (w *watchdog) stop() {
-	panic("not implemented")
+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(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://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmalert/README.md .
+`
+
+	f := flag.CommandLine.Output()
+	fmt.Fprintf(f, "%s\n", s)
+	flag.PrintDefaults()
 }

app/vmalert/main_test.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"fmt"
+	"net/url"
+	"os"
+	"testing"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+)
+
+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))
+	}
+}

app/vmalert/manager.go

@@ -0,0 +1,158 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"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 {
+	querier   datasource.Querier
+	notifiers []notifier.Notifier
+
+	rw *remotewrite.Client
+	rr datasource.Querier
+
+	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, path []string, validateTpl, validateExpr bool) error {
+	return m.update(ctx, path, validateTpl, validateExpr, 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) {
+	if restore && m.rr != nil {
+		err := group.Restore(ctx, m.rr, *remoteReadLookBack, m.labels)
+		if err != nil {
+			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.querier, m.notifiers, m.rw)
+		m.wg.Done()
+	}()
+	m.groups[id] = group
+}
+
+func (m *manager) update(ctx context.Context, path []string, validateTpl, validateExpr, restore bool) error {
+	logger.Infof("reading rules configuration file from %q", strings.Join(path, ";"))
+	groupsCfg, err := config.Parse(path, validateTpl, validateExpr)
+	if err != nil {
+		return fmt.Errorf("cannot parse configuration file: %w", err)
+	}
+
+	groupsRegistry := make(map[uint64]*Group)
+	for _, cfg := range groupsCfg {
+		ng := newGroup(cfg, *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 {
+		m.startGroup(ctx, ng, restore)
+	}
+	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,
+		File:        g.File,
+		Interval:    g.Interval.String(),
+		Concurrency: g.Concurrency,
+	}
+	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 +1,230 @@
+package main
+
+import (
+	"context"
+	"math/rand"
+	"net/url"
+	"os"
+	"sync"
+	"testing"
+	"time"
+
+	"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)}
+	path := []string{"foo/bar"}
+	err := m.update(context.Background(), path, true, true, false)
+	if 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),
+		querier:   &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",
+	}
+	*evaluationInterval = time.Millisecond
+	if err := m.start(context.Background(), []string{paths[0]}, true, true); 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))
+				path := []string{paths[rnd]}
+				_ = m.update(context.Background(), path, true, true, 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)",
+		}
+	)
+
+	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",
+					Interval: defaultEvalInterval,
+					Rules: []Rule{
+						&AlertingRule{
+							Name:   "VMRows",
+							Expr:   "vm_rows > 0",
+							For:    5 * time.Minute,
+							Labels: map[string]string{"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",
+					Rules:    []Rule{VMRows},
+					Interval: defaultEvalInterval,
+				},
+				{
+					File:     "config/testdata/rules0-good.rules",
+					Interval: defaultEvalInterval,
+					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",
+					Interval: defaultEvalInterval,
+					Rules:    []Rule{VMRows},
+				},
+				{
+					File:     "config/testdata/rules0-good.rules",
+					Interval: defaultEvalInterval,
+					Name:     "TestGroup", 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",
+					Interval: defaultEvalInterval,
+					Rules:    []Rule{VMRows},
+				},
+				{
+					File:     "config/testdata/rules0-good.rules",
+					Interval: defaultEvalInterval,
+					Name:     "TestGroup", Rules: []Rule{
+						Conns,
+						ExampleAlertAlwaysFiring,
+					},
+				},
+			},
+		},
+	}
+	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), querier: &fakeQuerier{}}
+			path := []string{tc.initPath}
+			if err := m.update(ctx, path, true, true, false); err != nil {
+				t.Fatalf("failed to complete initial rules update: %s", err)
+			}
+
+			path = []string{tc.updatePath}
+			_ = m.update(ctx, path, true, true, 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()
+		})
+	}
+}

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/notifier/alert.go

@@ -0,0 +1,109 @@
+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     uint64
+	Name        string
+	Labels      map[string]string
+	Annotations map[string]string
+	State       AlertState
+
+	Expr  string
+	Start time.Time
+	End   time.Time
+	Value float64
+	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"
+}
+
+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 give
+// map of annotations.
+func (a *Alert) ExecTemplate(annotations map[string]string) (map[string]string, error) {
+	tplData := alertTplData{Value: a.Value, Labels: a.Labels, Expr: a.Expr}
+	return templateAnnotations(annotations, tplHeader, tplData)
+}
+
+// ValidateTemplates validate annotations for possible template error, uses empty data for template population
+func ValidateTemplates(annotations map[string]string) error {
+	_, err := templateAnnotations(annotations, tplHeader, alertTplData{
+		Labels: map[string]string{},
+		Value:  0,
+	})
+	return err
+}
+
+func templateAnnotations(annotations map[string]string, header string, data alertTplData) (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 {
+		r[key] = text
+		buf.Reset()
+		builder.Reset()
+		builder.Grow(len(header) + len(text))
+		builder.WriteString(header)
+		builder.WriteString(text)
+		if err := templateAnnotation(&buf, builder.String(), data); err != nil {
+			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) error {
+	tpl, err := template.New("").Funcs(tmplFunc).Option("missingkey=zero").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 +1,82 @@
+package notifier
+
+import (
+	"testing"
+)
+
+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",
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			tpl, err := tc.alert.ExecTemplate(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 +1,68 @@
+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 {
+	alertURL      string
+	basicAuthUser string
+	basicAuthPass string
+	argFunc       AlertURLGenerator
+	client        *http.Client
+}
+
+// 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")
+	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 {
+	addr := strings.TrimSuffix(alertManagerURL, "/") + alertManagerPath
+	return &AlertManager{
+		alertURL:      addr,
+		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

@@ -1,22 +1,31 @@
-package provider
+package notifier
 
 import (
+	"context"
 	"encoding/json"
 	"net/http"
 	"net/http/httptest"
+	"strconv"
 	"testing"
 	"time"
-
-	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
 )
 
 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(alertsPath, func(w http.ResponseWriter, r *http.Request) {
+	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)
@@ -42,36 +51,38 @@ func TestAlertManager_Send(t *testing.T) {
 			if len(a) != 1 {
 				t.Errorf("expected 1 alert in array got %d", len(a))
 			}
-			if a[0].GeneratorURL != "alert0" {
-				t.Errorf("exptected alert0 as generatorURL got %s", a[0].GeneratorURL)
+			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("exptected alert0 as alert name got %s", a[0].Labels["alertname"])
+				t.Errorf("expected alert0 as alert name got %s", a[0].Labels["alertname"])
 			}
 			if a[0].StartsAt.IsZero() {
-				t.Errorf("exptected non-zero start time")
+				t.Errorf("expected non-zero start time")
 			}
 			if a[0].EndAt.IsZero() {
-				t.Errorf("exptected non-zero end time")
+				t.Errorf("expected non-zero end time")
 			}
 		}
 	})
 	srv := httptest.NewServer(mux)
 	defer srv.Close()
-	am := NewAlertManager(srv.URL, func(name string) string {
-		return name
+	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(&config.Alert{}); err == nil {
+	if err := am.Send(context.Background(), []Alert{{}, {}}); err == nil {
 		t.Error("expected connection error got nil")
 	}
-	if err := am.Send(&config.Alert{}); err == nil {
+	if err := am.Send(context.Background(), []Alert{}); err == nil {
 		t.Error("expected wrong http code error got nil")
 	}
-	if err := am.Send(&config.Alert{
-		Name:  "alert0",
-		Start: time.Now().UTC(),
-		End:   time.Now().UTC(),
-	}); err != 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 {

app/vmalert/notifier/init.go

@@ -0,0 +1,46 @@
+package notifier
+
+import (
+	"flag"
+	"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 -datasource.url")
+	basicAuthPassword = flagutil.NewArray("notifier.basicAuth.password", "Optional basic auth password for -datasource.url")
+
+	tlsInsecureSkipVerify = flag.Bool("notifier.tlsInsecureSkipVerify", false, "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)
+		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 +1,8 @@
+package notifier
+
+import "context"
+
+// Notifier is common interface for alert manager provider
+type Notifier interface {
+	Send(ctx context.Context, alerts []Alert) error
+}

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 +1,180 @@
+// 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 (
+	"fmt"
+	html_template "html/template"
+	"math"
+	"net/url"
+	"regexp"
+	"strings"
+	text_template "text/template"
+	"time"
+)
+
+var tmplFunc text_template.FuncMap
+
+// InitTemplateFunc returns template helper functions
+func InitTemplateFunc(externalURL *url.URL) {
+	tmplFunc = text_template.FuncMap{
+		"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
+		},
+		"reReplaceAll": func(pattern, repl, text string) string {
+			re := regexp.MustCompile(pattern)
+			return re.ReplaceAllString(text, repl)
+		},
+		"safeHtml": func(text string) html_template.HTML {
+			return html_template.HTML(text)
+		},
+		"match":   regexp.MatchString,
+		"title":   strings.Title,
+		"toUpper": strings.ToUpper,
+		"toLower": strings.ToLower,
+		"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": 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": 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": func(v float64) string {
+			return fmt.Sprintf("%.4g%%", v*100)
+		},
+		"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)
+		},
+		"pathPrefix": func() string {
+			return externalURL.Path
+		},
+		"externalURL": func() string {
+			return externalURL.String()
+		},
+		"pathEscape": func(u string) string {
+			return url.PathEscape(u)
+		},
+		"queryEscape": func(q string) string {
+			return url.QueryEscape(q)
+		},
+		"quotesEscape": func(q string) string {
+			return strings.Replace(q, `"`, `\"`, -1)
+		},
+	}
+}
+
+// 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/provider/alert_manager_request.qtpl

@@ -1,26 +0,0 @@
-{% import (
-    "time"
-	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
-) %}
-{% stripspace %}
-
-{% func amRequest(alert *config.Alert, generatorURL string) %}
-{
-	"startsAt":{%q= alert.Start.Format(time.RFC3339Nano) %},
-	"generatorURL": {%q= generatorURL %},
-    {% 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": {
-        "summary": {%q= alert.Annotations.Summary %},
-        "description": {%q= alert.Annotations.Description %}
-    }
-}
-{% endfunc %}
-{% endstripspace %}

app/vmalert/provider/alert_manager_request.qtpl.go

@@ -1,101 +0,0 @@
-// Code generated by qtc from "alert_manager_request.qtpl". DO NOT EDIT.
-// See https://github.com/valyala/quicktemplate for details.
-
-//line app/vmalert/provider/alert_manager_request.qtpl:1
-package provider
-
-//line app/vmalert/provider/alert_manager_request.qtpl:1
-import (
-	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
-	"time"
-)
-
-//line app/vmalert/provider/alert_manager_request.qtpl:7
-import (
-	qtio422016 "io"
-
-	qt422016 "github.com/valyala/quicktemplate"
-)
-
-//line app/vmalert/provider/alert_manager_request.qtpl:7
-var (
-	_ = qtio422016.Copy
-	_ = qt422016.AcquireByteBuffer
-)
-
-//line app/vmalert/provider/alert_manager_request.qtpl:7
-func streamamRequest(qw422016 *qt422016.Writer, alert *config.Alert, generatorURL string) {
-//line app/vmalert/provider/alert_manager_request.qtpl:7
-	qw422016.N().S(`{"startsAt":`)
-//line app/vmalert/provider/alert_manager_request.qtpl:9
-	qw422016.N().Q(alert.Start.Format(time.RFC3339Nano))
-//line app/vmalert/provider/alert_manager_request.qtpl:9
-	qw422016.N().S(`,"generatorURL":`)
-//line app/vmalert/provider/alert_manager_request.qtpl:10
-	qw422016.N().Q(generatorURL)
-//line app/vmalert/provider/alert_manager_request.qtpl:10
-	qw422016.N().S(`,`)
-//line app/vmalert/provider/alert_manager_request.qtpl:11
-	if !alert.End.IsZero() {
-//line app/vmalert/provider/alert_manager_request.qtpl:11
-		qw422016.N().S(`"endsAt":`)
-//line app/vmalert/provider/alert_manager_request.qtpl:12
-		qw422016.N().Q(alert.End.Format(time.RFC3339Nano))
-//line app/vmalert/provider/alert_manager_request.qtpl:12
-		qw422016.N().S(`,`)
-//line app/vmalert/provider/alert_manager_request.qtpl:13
-	}
-//line app/vmalert/provider/alert_manager_request.qtpl:13
-	qw422016.N().S(`"labels": {"alertname":`)
-//line app/vmalert/provider/alert_manager_request.qtpl:15
-	qw422016.N().Q(alert.Name)
-//line app/vmalert/provider/alert_manager_request.qtpl:16
-	for k, v := range alert.Labels {
-//line app/vmalert/provider/alert_manager_request.qtpl:16
-		qw422016.N().S(`,`)
-//line app/vmalert/provider/alert_manager_request.qtpl:17
-		qw422016.N().Q(k)
-//line app/vmalert/provider/alert_manager_request.qtpl:17
-		qw422016.N().S(`:`)
-//line app/vmalert/provider/alert_manager_request.qtpl:17
-		qw422016.N().Q(v)
-//line app/vmalert/provider/alert_manager_request.qtpl:18
-	}
-//line app/vmalert/provider/alert_manager_request.qtpl:18
-	qw422016.N().S(`},"annotations": {"summary":`)
-//line app/vmalert/provider/alert_manager_request.qtpl:21
-	qw422016.N().Q(alert.Annotations.Summary)
-//line app/vmalert/provider/alert_manager_request.qtpl:21
-	qw422016.N().S(`,"description":`)
-//line app/vmalert/provider/alert_manager_request.qtpl:22
-	qw422016.N().Q(alert.Annotations.Description)
-//line app/vmalert/provider/alert_manager_request.qtpl:22
-	qw422016.N().S(`}}`)
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-}
-
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-func writeamRequest(qq422016 qtio422016.Writer, alert *config.Alert, generatorURL string) {
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-	qw422016 := qt422016.AcquireWriter(qq422016)
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-	streamamRequest(qw422016, alert, generatorURL)
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-	qt422016.ReleaseWriter(qw422016)
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-}
-
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-func amRequest(alert *config.Alert, generatorURL string) string {
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-	qb422016 := qt422016.AcquireByteBuffer()
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-	writeamRequest(qb422016, alert, generatorURL)
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-	qs422016 := string(qb422016.B)
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-	qt422016.ReleaseByteBuffer(qb422016)
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-	return qs422016
-//line app/vmalert/provider/alert_manager_request.qtpl:25
-}

app/vmalert/provider/alertmanager.go

@@ -1,66 +0,0 @@
-package provider
-
-import (
-	"bytes"
-	"fmt"
-	"io"
-	"net/http"
-	"strings"
-	"sync"
-
-	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
-)
-
-const alertsPath = "/api/v2/alerts"
-
-var pool = sync.Pool{New: func() interface{} {
-	return &bytes.Buffer{}
-}}
-
-// AlertManager represents integration provider with Prometheus alert manager
-type AlertManager struct {
-	alertURL string
-	argFunc  AlertURLGenerator
-	client   *http.Client
-}
-
-// AlertURLGenerator returns URL to single alert by given name
-type AlertURLGenerator func(name string) string
-
-// NewAlertManager is a constructor for AlertManager
-func NewAlertManager(alertManagerURL string, fn AlertURLGenerator, c *http.Client) *AlertManager {
-	return &AlertManager{
-		alertURL: strings.TrimSuffix(alertManagerURL, "/") + alertsPath,
-		argFunc:  fn,
-		client:   c,
-	}
-}
-
-const (
-	jsonArrayOpen  byte = 91 // [
-	jsonArrayClose byte = 93 // ]
-)
-
-// Send an alert or resolve message
-func (am *AlertManager) Send(alert *config.Alert) error {
-	b := pool.Get().(*bytes.Buffer)
-	b.Reset()
-	defer pool.Put(b)
-	b.WriteByte(jsonArrayOpen)
-	writeamRequest(b, alert, am.argFunc(alert.Name))
-	b.WriteByte(jsonArrayClose)
-	resp, err := am.client.Post(am.alertURL, "application/json", b)
-	if err != nil {
-		return err
-	}
-	defer func() { _ = resp.Body.Close() }()
-	if resp.StatusCode != http.StatusOK {
-		b.Reset()
-		if _, err := io.Copy(b, resp.Body); err != nil {
-			logger.Errorf("unable to copy error response body to buffer %s", err)
-		}
-		return fmt.Errorf("invalid response from alertmanager %s", b)
-	}
-	return nil
-}

app/vmalert/provider/common.go

@@ -1,8 +0,0 @@
-package provider
-
-import "github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
-
-// AlertProvider is common interface for alert manager provider
-type AlertProvider interface {
-	Send(rule config.Alert) error
-}

app/vmalert/recording.go

@@ -0,0 +1,173 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"hash/fnv"
+	"sort"
+	"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 {
+	RuleID  uint64
+	Name    string
+	Expr    string
+	Labels  map[string]string
+	GroupID uint64
+
+	// 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
+
+	metrics *recordingRuleMetrics
+}
+
+type recordingRuleMetrics struct {
+	errors *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(group *Group, cfg config.Rule) *RecordingRule {
+	rr := &RecordingRule{
+		RuleID:  cfg.ID,
+		Name:    cfg.Record,
+		Expr:    cfg.Expr,
+		Labels:  cfg.Labels,
+		GroupID: group.ID(),
+		metrics: &recordingRuleMetrics{},
+	}
+	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.Lock()
+			defer rr.mu.Unlock()
+			if rr.lastExecError == nil {
+				return 0
+			}
+			return 1
+		})
+	return rr
+}
+
+// Close unregisters rule metrics
+func (rr *RecordingRule) Close() {
+	metrics.UnregisterMetric(rr.metrics.errors.name)
+}
+
+var errDuplicate = errors.New("result contains metrics with the same labelset after applying rule labels")
+
+// Exec executes RecordingRule expression via the given Querier.
+func (rr *RecordingRule) Exec(ctx context.Context, q datasource.Querier, series bool) ([]prompbmarshal.TimeSeries, error) {
+	if !series {
+		return nil, nil
+	}
+
+	qMetrics, err := q.Query(ctx, rr.Expr)
+
+	rr.mu.Lock()
+	defer rr.mu.Unlock()
+
+	rr.lastExecTime = time.Now()
+	rr.lastExecError = err
+	if err != nil {
+		return nil, fmt.Errorf("failed to execute query %q: %w", rr.Expr, err)
+	}
+
+	duplicates := make(map[uint64]prompbmarshal.TimeSeries, len(qMetrics))
+	var tss []prompbmarshal.TimeSeries
+	for _, r := range qMetrics {
+		ts := rr.toTimeSeries(r, rr.lastExecTime)
+		h := hashTimeSeries(ts)
+		if _, ok := duplicates[h]; ok {
+			rr.lastExecError = errDuplicate
+			return nil, errDuplicate
+		}
+		duplicates[h] = ts
+		tss = append(tss, ts)
+	}
+	return tss, nil
+}
+
+func hashTimeSeries(ts prompbmarshal.TimeSeries) uint64 {
+	hash := fnv.New64a()
+	labels := ts.Labels
+	sort.Slice(labels, func(i, j int) bool {
+		return labels[i].Name < labels[j].Name
+	})
+	for _, l := range labels {
+		hash.Write([]byte(l.Name))
+		hash.Write([]byte(l.Value))
+		hash.Write([]byte("\xff"))
+	}
+	return hash.Sum64()
+}
+
+func (rr *RecordingRule) toTimeSeries(m datasource.Metric, timestamp time.Time) 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.Value, labels, timestamp)
+}
+
+// UpdateWith copies all significant fields.
+// alerts state isn't copied since
+// it should be updated in next 2 Execs
+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
+	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,
+		Expression: rr.Expr,
+		LastError:  lastErr,
+		LastExec:   rr.lastExecTime,
+		Labels:     rr.Labels,
+	}
+}

app/vmalert/recording_test.go

@@ -0,0 +1,121 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+)
+
+func TestRecoridngRule_ToTimeSeries(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(10, map[string]string{
+					"__name__": "foo",
+				}, timestamp),
+			},
+		},
+		{
+			&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(1, map[string]string{
+					"__name__": "foobarbaz",
+					"job":      "foo",
+				}, timestamp),
+				newTimeSeries(2, map[string]string{
+					"__name__": "foobarbaz",
+					"job":      "bar",
+				}, timestamp),
+				newTimeSeries(3, map[string]string{
+					"__name__": "foobarbaz",
+					"job":      "baz",
+				}, timestamp),
+			},
+		},
+		{
+			&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(2, map[string]string{
+					"__name__": "job:foo",
+					"job":      "foo",
+					"source":   "test",
+				}, timestamp),
+				newTimeSeries(1, map[string]string{
+					"__name__": "job:foo",
+					"job":      "bar",
+					"source":   "test",
+				}, timestamp),
+			},
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.rule.Name, func(t *testing.T) {
+			fq := &fakeQuerier{}
+			fq.add(tc.metrics...)
+			tss, err := tc.rule.Exec(context.TODO(), fq, true)
+			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_ToTimeSeriesNegative(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))
+
+	_, err := rr.Exec(context.TODO(), fq, true)
+	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(), fq, true)
+	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 +1,39 @@
+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 Victoria Metrics 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")
+	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.Querier, 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)
+	}
+	c := &http.Client{Transport: tr}
+	return datasource.NewVMStorage(*addr, *basicAuthUsername, *basicAuthPassword, 0, c), nil
+}

app/vmalert/remotewrite/init.go

@@ -0,0 +1,54 @@
+package remotewrite
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/utils"
+)
+
+var (
+	addr = flag.String("remoteWrite.url", "", "Optional URL to Victoria Metrics or VMInsert where to persist alerts state"+
+		" and recording rules results in form of timeseries. E.g. http://127.0.0.1:8428")
+	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")
+
+	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")
+)
+
+// 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)
+	}
+
+	return NewClient(ctx, Config{
+		Addr:          *addr,
+		Concurrency:   *concurrency,
+		MaxQueueSize:  *maxQueueSize,
+		MaxBatchSize:  *maxBatchSize,
+		FlushInterval: *flushInterval,
+		BasicAuthUser: *basicAuthUsername,
+		BasicAuthPass: *basicAuthPassword,
+		Transport:     t,
+	})
+}

app/vmalert/remotewrite/remotewrite.go

@@ -0,0 +1,246 @@
+package remotewrite
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+	"github.com/VictoriaMetrics/metrics"
+	"github.com/golang/snappy"
+)
+
+// Client is an asynchronous HTTP client for writing
+// timeseries via remote write protocol.
+type Client struct {
+	addr           string
+	c              *http.Client
+	input          chan prompbmarshal.TimeSeries
+	baUser, baPass string
+	flushInterval  time.Duration
+	maxBatchSize   int
+	maxQueueSize   int
+
+	wg     sync.WaitGroup
+	doneCh chan struct{}
+}
+
+// Config is config for remote write.
+type Config struct {
+	// Addr of remote storage
+	Addr string
+
+	BasicAuthUser string
+	BasicAuthPass string
+
+	// 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
+}
+
+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()
+	}
+	c := &Client{
+		c: &http.Client{
+			Timeout:   cfg.WriteTimeout,
+			Transport: cfg.Transport,
+		},
+		addr:          strings.TrimSuffix(cfg.Addr, "/") + writePath,
+		baUser:        cfg.BasicAuthUser,
+		baPass:        cfg.BasicAuthPass,
+		flushInterval: cfg.FlushInterval,
+		maxBatchSize:  cfg.MaxBatchSize,
+		maxQueueSize:  cfg.MaxQueueSize,
+		doneCh:        make(chan struct{}),
+		input:         make(chan prompbmarshal.TimeSeries, cfg.MaxQueueSize),
+	}
+	cc := defaultConcurrency
+	if cfg.Concurrency > 0 {
+		cc = cfg.Concurrency
+	}
+	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`)
+)
+
+// 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)
+
+	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.baPass != "" {
+		req.SetBasicAuth(c.baUser, c.baPass)
+	}
+	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 {
+		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/rule.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"context"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+)
+
+// Rule represents alerting or recording rule
+// that has unique ID, can be Executed and
+// updated with other Rule.
+type Rule interface {
+	// Returns unique ID that may be used for
+	// identifying this Rule among others.
+	ID() uint64
+	// Exec executes the rule with given context
+	// and Querier. If returnSeries is true, Exec
+	// may return TimeSeries as result of execution
+	Exec(ctx context.Context, q datasource.Querier, returnSeries bool) ([]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()
+}

app/vmalert/utils.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"sort"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+)
+
+func newTimeSeries(value float64, labels map[string]string, timestamp time.Time) prompbmarshal.TimeSeries {
+	ts := prompbmarshal.TimeSeries{}
+	ts.Samples = append(ts.Samples, prompbmarshal.Sample{
+		Value:     value,
+		Timestamp: timestamp.UnixNano() / 1e6,
+	})
+	keys := make([]string, 0, len(labels))
+	for k := range labels {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	for _, key := range keys {
+		ts.Labels = append(ts.Labels, prompbmarshal.Label{
+			Name:  key,
+			Value: labels[key],
+		})
+	}
+	return ts
+}

app/vmalert/utils/err_group.go

@@ -0,0 +1,43 @@
+package utils
+
+import (
+	"fmt"
+	"strings"
+)
+
+// ErrGroup accumulates multiple errors
+// and produces single error message.
+type ErrGroup struct {
+	errs []error
+}
+
+// Add adds a new error to group.
+// Isn't thread-safe.
+func (eg *ErrGroup) Add(err error) {
+	eg.errs = append(eg.errs, err)
+}
+
+// Err checks if group contains at least
+// one error.
+func (eg *ErrGroup) Err() error {
+	if eg == nil || len(eg.errs) == 0 {
+		return nil
+	}
+	return eg
+}
+
+// Error satisfies Error interface
+func (eg *ErrGroup) Error() string {
+	if len(eg.errs) == 0 {
+		return ""
+	}
+	var b strings.Builder
+	fmt.Fprintf(&b, "errors(%d): ", len(eg.errs))
+	for i, err := range eg.errs {
+		b.WriteString(err.Error())
+		if i != len(eg.errs)-1 {
+			b.WriteString("\n")
+		}
+	}
+	return b.String()
+}

app/vmalert/utils/err_group_test.go

@@ -0,0 +1,38 @@
+package utils
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestErrGroup(t *testing.T) {
+	testCases := []struct {
+		errs []error
+		exp  string
+	}{
+		{nil, ""},
+		{[]error{errors.New("timeout")}, "errors(1): timeout"},
+		{
+			[]error{errors.New("timeout"), errors.New("deadline")},
+			"errors(2): timeout\ndeadline",
+		},
+	}
+	for _, tc := range testCases {
+		eg := new(ErrGroup)
+		for _, err := range tc.errs {
+			eg.Add(err)
+		}
+		if len(tc.errs) == 0 {
+			if eg.Err() != nil {
+				t.Fatalf("expected to get nil error")
+			}
+			continue
+		}
+		if eg.Err() == nil {
+			t.Fatalf("expected to get non-nil error")
+		}
+		if eg.Error() != tc.exp {
+			t.Fatalf("expected to have: \n%q\ngot:\n%q", tc.exp, eg.Error())
+		}
+	}
+}

app/vmalert/utils/tls.go

@@ -0,0 +1,58 @@
+package utils
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"strings"
+)
+
+// Transport creates http.Transport object based on provided URL.
+// Returns Transport with TLS configuration if URL contains `https` prefix
+func Transport(URL, certFile, keyFile, CAFile, serverName string, insecureSkipVerify bool) (*http.Transport, error) {
+	t := http.DefaultTransport.(*http.Transport).Clone()
+	if !strings.HasPrefix(URL, "https") {
+		return t, nil
+	}
+	tlsCfg, err := TLSConfig(certFile, keyFile, CAFile, serverName, insecureSkipVerify)
+	if err != nil {
+		return nil, err
+	}
+	t.TLSClientConfig = tlsCfg
+	return t, nil
+}
+
+// TLSConfig creates tls.Config object from provided arguments
+func TLSConfig(certFile, keyFile, CAFile, serverName string, insecureSkipVerify bool) (*tls.Config, error) {
+	var certs []tls.Certificate
+	if certFile != "" {
+		cert, err := tls.LoadX509KeyPair(certFile, keyFile)
+		if err != nil {
+			return nil, fmt.Errorf("cannot load TLS certificate from `cert_file`=%q, `key_file`=%q: %w", certFile, keyFile, err)
+		}
+
+		certs = []tls.Certificate{cert}
+	}
+
+	var rootCAs *x509.CertPool
+	if CAFile != "" {
+		pem, err := ioutil.ReadFile(CAFile)
+		if err != nil {
+			return nil, fmt.Errorf("cannot read `ca_file` %q: %w", CAFile, err)
+		}
+
+		rootCAs = x509.NewCertPool()
+		if !rootCAs.AppendCertsFromPEM(pem) {
+			return nil, fmt.Errorf("cannot parse data from `ca_file` %q", CAFile)
+		}
+	}
+
+	return &tls.Config{
+		Certificates:       certs,
+		InsecureSkipVerify: insecureSkipVerify,
+		RootCAs:            rootCAs,
+		ServerName:         serverName,
+	}, nil
+}

app/vmalert/utils/tls_test.go

@@ -0,0 +1,52 @@
+package utils
+
+import "testing"
+
+func TestTLSConfig(t *testing.T) {
+	var certFile, keyFile, CAFile, serverName string
+	var insecureSkipVerify bool
+	serverName = "test"
+	insecureSkipVerify = true
+	tlsCfg, err := TLSConfig(certFile, keyFile, CAFile, serverName, insecureSkipVerify)
+	if err != nil {
+		t.Errorf("unexpected error %s", err)
+	}
+	if tlsCfg == nil {
+		t.Errorf("expected tlsConfig to be set, got nil")
+	}
+	if tlsCfg.ServerName != serverName {
+		t.Errorf("unexpected ServerName, want %s, got %s", serverName, tlsCfg.ServerName)
+	}
+	if tlsCfg.InsecureSkipVerify != insecureSkipVerify {
+		t.Errorf("unexpected InsecureSkipVerify, want %v, got %v", insecureSkipVerify, tlsCfg.InsecureSkipVerify)
+	}
+	certFile = "/path/to/nonexisting/cert/file"
+	_, err = TLSConfig(certFile, keyFile, CAFile, serverName, insecureSkipVerify)
+	if err == nil {
+		t.Errorf("expected keypair error, got nil")
+	}
+	certFile = ""
+	CAFile = "/path/to/nonexisting/cert/file"
+	_, err = TLSConfig(certFile, keyFile, CAFile, serverName, insecureSkipVerify)
+	if err == nil {
+		t.Errorf("expected read error, got nil")
+	}
+}
+
+func TestTransport(t *testing.T) {
+	var certFile, keyFile, CAFile, serverName string
+	var insecureSkipVerify bool
+	URL := "http://victoriametrics.com"
+	_, err := Transport(URL, certFile, keyFile, CAFile, serverName, insecureSkipVerify)
+	if err != nil {
+		t.Errorf("unexpected error %s", err)
+	}
+	URL = "https://victoriametrics.com"
+	tr, err := Transport(URL, certFile, keyFile, CAFile, serverName, insecureSkipVerify)
+	if err != nil {
+		t.Errorf("unexpected error %s", err)
+	}
+	if tr.TLSClientConfig == nil {
+		t.Errorf("expected TLSClientConfig to be set, got nil")
+	}
+}

app/vmalert/web.go

@@ -0,0 +1,185 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"sort"
+	"strconv"
+	"strings"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
+)
+
+type requestHandler struct {
+	m *manager
+}
+
+var pathList = [][]string{
+	{"/api/v1/groups", "list all loaded groups and rules"},
+	{"/api/v1/alerts", "list all active alerts"},
+	{"/api/v1/groupID/alertID/status", "get alert status by ID"},
+	// /metrics is served by httpserver by default
+	{"/metrics", "list of application metrics"},
+	{"/-/reload", "reload configuration"},
+}
+
+func (rh *requestHandler) handler(w http.ResponseWriter, r *http.Request) bool {
+	switch r.URL.Path {
+	case "/":
+		for _, path := range pathList {
+			p, doc := path[0], path[1]
+			fmt.Fprintf(w, "<a href='%s'>%q</a> - %s<br/>", p, p, doc)
+		}
+		return true
+	case "/api/v1/groups":
+		data, err := rh.listGroups()
+		if err != nil {
+			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
+			return true
+		}
+		w.Header().Set("Content-Type", "application/json")
+		w.Write(data)
+		return true
+	case "/api/v1/alerts":
+		data, err := rh.listAlerts()
+		if err != nil {
+			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
+			return true
+		}
+		w.Header().Set("Content-Type", "application/json")
+		w.Write(data)
+		return true
+	case "/-/reload":
+		logger.Infof("api config reload was called, sending sighup")
+		procutil.SelfSIGHUP()
+		w.WriteHeader(http.StatusOK)
+		return true
+	default:
+		if !strings.HasSuffix(r.URL.Path, "/status") {
+			return false
+		}
+		// /api/v1/<groupName>/<alertID>/status
+		data, err := rh.alert(r.URL.Path)
+		if err != nil {
+			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
+			return true
+		}
+		w.Header().Set("Content-Type", "application/json")
+		w.Write(data)
+		return true
+	}
+}
+
+type listGroupsResponse struct {
+	Data struct {
+		Groups []APIGroup `json:"groups"`
+	} `json:"data"`
+	Status string `json:"status"`
+}
+
+func (rh *requestHandler) listGroups() ([]byte, error) {
+	rh.m.groupsMu.RLock()
+	defer rh.m.groupsMu.RUnlock()
+
+	lr := listGroupsResponse{Status: "success"}
+	for _, g := range rh.m.groups {
+		lr.Data.Groups = append(lr.Data.Groups, g.toAPI())
+	}
+
+	// sort list of alerts for deterministic output
+	sort.Slice(lr.Data.Groups, func(i, j int) bool {
+		return lr.Data.Groups[i].Name < lr.Data.Groups[j].Name
+	})
+
+	b, err := json.Marshal(lr)
+	if err != nil {
+		return nil, &httpserver.ErrorWithStatusCode{
+			Err:        fmt.Errorf(`error encoding list of active alerts: %w`, err),
+			StatusCode: http.StatusInternalServerError,
+		}
+	}
+	return b, nil
+}
+
+type listAlertsResponse struct {
+	Data struct {
+		Alerts []*APIAlert `json:"alerts"`
+	} `json:"data"`
+	Status string `json:"status"`
+}
+
+func (rh *requestHandler) listAlerts() ([]byte, error) {
+	rh.m.groupsMu.RLock()
+	defer rh.m.groupsMu.RUnlock()
+
+	lr := listAlertsResponse{Status: "success"}
+	for _, g := range rh.m.groups {
+		for _, r := range g.Rules {
+			a, ok := r.(*AlertingRule)
+			if !ok {
+				continue
+			}
+			lr.Data.Alerts = append(lr.Data.Alerts, a.AlertsAPI()...)
+		}
+	}
+
+	// sort list of alerts for deterministic output
+	sort.Slice(lr.Data.Alerts, func(i, j int) bool {
+		return lr.Data.Alerts[i].ID < lr.Data.Alerts[j].ID
+	})
+
+	b, err := json.Marshal(lr)
+	if err != nil {
+		return nil, &httpserver.ErrorWithStatusCode{
+			Err:        fmt.Errorf(`error encoding list of active alerts: %w`, err),
+			StatusCode: http.StatusInternalServerError,
+		}
+	}
+	return b, nil
+}
+
+func (rh *requestHandler) alert(path string) ([]byte, error) {
+	rh.m.groupsMu.RLock()
+	defer rh.m.groupsMu.RUnlock()
+
+	parts := strings.SplitN(strings.TrimPrefix(path, "/api/v1/"), "/", 3)
+	if len(parts) != 3 {
+		return nil, &httpserver.ErrorWithStatusCode{
+			Err:        fmt.Errorf(`path %q cointains /status suffix but doesn't match pattern "/group/alert/status"`, path),
+			StatusCode: http.StatusBadRequest,
+		}
+	}
+
+	groupID, err := uint64FromPath(parts[0])
+	if err != nil {
+		return nil, badRequest(fmt.Errorf(`cannot parse groupID: %w`, err))
+	}
+	alertID, err := uint64FromPath(parts[1])
+	if err != nil {
+		return nil, badRequest(fmt.Errorf(`cannot parse alertID: %w`, err))
+	}
+	resp, err := rh.m.AlertAPI(groupID, alertID)
+	if err != nil {
+		return nil, errResponse(err, http.StatusNotFound)
+	}
+	return json.Marshal(resp)
+}
+
+func uint64FromPath(path string) (uint64, error) {
+	s := strings.TrimRight(path, "/")
+	return strconv.ParseUint(s, 10, 0)
+}
+
+func badRequest(err error) *httpserver.ErrorWithStatusCode {
+	return errResponse(err, http.StatusBadRequest)
+}
+
+func errResponse(err error, sc int) *httpserver.ErrorWithStatusCode {
+	return &httpserver.ErrorWithStatusCode{
+		Err:        err,
+		StatusCode: sc,
+	}
+}

app/vmalert/web_test.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"reflect"
+	"testing"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
+)
+
+func TestHandler(t *testing.T) {
+	ar := &AlertingRule{
+		Name: "alert",
+		alerts: map[uint64]*notifier.Alert{
+			0: {},
+		},
+	}
+	g := &Group{
+		Name:  "group",
+		Rules: []Rule{ar},
+	}
+	m := &manager{groups: make(map[uint64]*Group)}
+	m.groups[0] = g
+	rh := &requestHandler{m: m}
+
+	getResp := func(url string, to interface{}, code int) {
+		t.Helper()
+		resp, err := http.Get(url)
+		if err != nil {
+			t.Errorf("unexpected err %s", err)
+		}
+		if code != resp.StatusCode {
+			t.Errorf("unexpected status code %d want %d", resp.StatusCode, code)
+		}
+		defer func() {
+			if err := resp.Body.Close(); err != nil {
+				t.Errorf("err closing body %s", err)
+			}
+		}()
+		if to != nil {
+			if err = json.NewDecoder(resp.Body).Decode(to); err != nil {
+				t.Errorf("unexpected err %s", err)
+			}
+		}
+	}
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { rh.handler(w, r) }))
+	defer ts.Close()
+	t.Run("/api/v1/alerts", func(t *testing.T) {
+		lr := listAlertsResponse{}
+		getResp(ts.URL+"/api/v1/alerts", &lr, 200)
+		if length := len(lr.Data.Alerts); length != 1 {
+			t.Errorf("expected 1 alert got %d", length)
+		}
+	})
+	t.Run("/api/v1/groups", func(t *testing.T) {
+		lr := listGroupsResponse{}
+		getResp(ts.URL+"/api/v1/groups", &lr, 200)
+		if length := len(lr.Data.Groups); length != 1 {
+			t.Errorf("expected 1 group got %d", length)
+		}
+	})
+	t.Run("/api/v1/0/0/status", func(t *testing.T) {
+		alert := &APIAlert{}
+		getResp(ts.URL+"/api/v1/0/0/status", alert, 200)
+		expAlert := ar.newAlertAPI(*ar.alerts[0])
+		if !reflect.DeepEqual(alert, expAlert) {
+			t.Errorf("expected %v is equal to %v", alert, expAlert)
+		}
+	})
+	t.Run("/api/v1/0/1/status", func(t *testing.T) {
+		getResp(ts.URL+"/api/v1/0/1/status", nil, 404)
+	})
+	t.Run("/api/v1/1/0/status", func(t *testing.T) {
+		getResp(ts.URL+"/api/v1/1/0/status", nil, 404)
+	})
+	t.Run("/", func(t *testing.T) {
+		getResp(ts.URL, nil, 200)
+	})
+}

app/vmalert/web_types.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"time"
+)
+
+// APIAlert represents an notifier.AlertingRule state
+// for WEB view
+type APIAlert struct {
+	ID          string            `json:"id"`
+	Name        string            `json:"name"`
+	GroupID     string            `json:"group_id"`
+	Expression  string            `json:"expression"`
+	State       string            `json:"state"`
+	Value       string            `json:"value"`
+	Labels      map[string]string `json:"labels"`
+	Annotations map[string]string `json:"annotations"`
+	ActiveAt    time.Time         `json:"activeAt"`
+}
+
+// APIGroup represents Group for WEB view
+type APIGroup struct {
+	Name           string             `json:"name"`
+	ID             string             `json:"id"`
+	File           string             `json:"file"`
+	Interval       string             `json:"interval"`
+	Concurrency    int                `json:"concurrency"`
+	AlertingRules  []APIAlertingRule  `json:"alerting_rules"`
+	RecordingRules []APIRecordingRule `json:"recording_rules"`
+}
+
+// APIAlertingRule represents AlertingRule for WEB view
+type APIAlertingRule struct {
+	ID          string            `json:"id"`
+	Name        string            `json:"name"`
+	GroupID     string            `json:"group_id"`
+	Expression  string            `json:"expression"`
+	For         string            `json:"for"`
+	LastError   string            `json:"last_error"`
+	LastExec    time.Time         `json:"last_exec"`
+	Labels      map[string]string `json:"labels"`
+	Annotations map[string]string `json:"annotations"`
+}
+
+// APIRecordingRule represents RecordingRule for WEB view
+type APIRecordingRule struct {
+	ID         string            `json:"id"`
+	Name       string            `json:"name"`
+	GroupID    string            `json:"group_id"`
+	Expression string            `json:"expression"`
+	LastError  string            `json:"last_error"`
+	LastExec   time.Time         `json:"last_exec"`
+	Labels     map[string]string `json:"labels"`
+}

app/vmauth/Makefile

@@ -0,0 +1,79 @@
+# All these commands must run from repository root.
+
+vmauth:
+	APP_NAME=vmauth $(MAKE) app-local
+
+vmauth-race:
+	APP_NAME=vmauth RACE=-race $(MAKE) app-local
+
+vmauth-prod:
+	APP_NAME=vmauth $(MAKE) app-via-docker
+
+vmauth-pure-prod:
+	APP_NAME=vmauth $(MAKE) app-via-docker-pure
+
+vmauth-amd64-prod:
+	APP_NAME=vmauth $(MAKE) app-via-docker-amd64
+
+vmauth-arm-prod:
+	APP_NAME=vmauth $(MAKE) app-via-docker-arm
+
+vmauth-arm64-prod:
+	APP_NAME=vmauth $(MAKE) app-via-docker-arm64
+
+vmauth-ppc64le-prod:
+	APP_NAME=vmauth $(MAKE) app-via-docker-ppc64le
+
+vmauth-386-prod:
+	APP_NAME=vmauth $(MAKE) app-via-docker-386
+
+package-vmauth:
+	APP_NAME=vmauth $(MAKE) package-via-docker
+
+package-vmauth-pure:
+	APP_NAME=vmauth $(MAKE) package-via-docker-pure
+
+package-vmauth-amd64:
+	APP_NAME=vmauth $(MAKE) package-via-docker-amd64
+
+package-vmauth-arm:
+	APP_NAME=vmauth $(MAKE) package-via-docker-arm
+
+package-vmauth-arm64:
+	APP_NAME=vmauth $(MAKE) package-via-docker-arm64
+
+package-vmauth-ppc64le:
+	APP_NAME=vmauth $(MAKE) package-via-docker-ppc64le
+
+package-vmauth-386:
+	APP_NAME=vmauth $(MAKE) package-via-docker-386
+
+publish-vmauth:
+	APP_NAME=vmauth $(MAKE) publish-via-docker
+
+run-vmauth:
+	APP_NAME=vmauth \
+	DOCKER_OPTS='-v $(shell pwd)/app/vmauth/:/app/vmauth' \
+	ARGS='-auth.config=app/vmauth/example_config.yml' \
+	$(MAKE) run-via-docker
+
+vmauth-amd64:
+	CGO_ENABLED=1 GOARCH=amd64 $(MAKE) vmauth-local-with-goarch
+
+vmauth-arm:
+	CGO_ENABLED=0 GOARCH=arm $(MAKE) vmauth-local-with-goarch
+
+vmauth-arm64:
+	CGO_ENABLED=0 GOARCH=arm64 $(MAKE) vmauth-local-with-goarch
+
+vmauth-ppc64le:
+	CGO_ENABLED=0 GOARCH=ppc64le $(MAKE) vmauth-local-with-goarch
+
+vmauth-386:
+	CGO_ENABLED=0 GOARCH=386 $(MAKE) vmauth-local-with-goarch
+
+vmauth-local-with-goarch:
+	APP_NAME=vmauth $(MAKE) app-local-with-goarch
+
+vmauth-pure:
+	APP_NAME=vmauth $(MAKE) app-local-pure

app/vmauth/README.md

@@ -0,0 +1,207 @@
+## vmauth
+
+`vmauth` is a simple auth proxy and router for [VictoriaMetrics](https://github.com/VictoriaMetrics/VictoriaMetrics).
+It reads username and password from [Basic Auth headers](https://en.wikipedia.org/wiki/Basic_access_authentication),
+matches them against configs pointed by `-auth.config` command-line flag and proxies incoming HTTP requests to the configured per-user `url_prefix` on successful match.
+
+
+### Quick start
+
+Just download `vmutils-*` archive from [releases page](https://github.com/VictoriaMetrics/VictoriaMetrics/releases), unpack it
+and pass the following flag to `vmauth` binary in order to start authorizing and routing requests:
+
+```
+/path/to/vmauth -auth.config=/path/to/auth/config.yml
+```
+
+After that `vmauth` starts accepting HTTP requests on port `8427` and routing them according to the provided [-auth.config](#auth-config).
+The port can be modified via `-httpListenAddr` command-line flag.
+
+The auth config can be reloaded by passing `SIGHUP` signal to `vmauth`.
+
+Docker images for `vmauth` are available [here](https://hub.docker.com/r/victoriametrics/vmauth/tags).
+
+Pass `-help` to `vmauth` in order to see all the supported command-line flags with their descriptions.
+
+Feel free [contacting us](mailto:info@victoriametrics.com) if you need customized auth proxy for VictoriaMetrics with the support of LDAP, SSO, RBAC, SAML, accounting, limits, etc.
+
+
+### Auth config
+
+Auth config is represented in the following simple `yml` format:
+
+```yml
+
+# Arbitrary number of usernames may be put here.
+# Usernames must be unique.
+
+users:
+
+  # The user for querying local single-node VictoriaMetrics.
+  # All the requests to http://vmauth:8427 with the given Basic Auth (username:password)
+  # will be routed to http://localhost:8428 .
+  # For example, http://vmauth:8427/api/v1/query is routed to http://localhost:8428/api/v1/query
+- username: "local-single-node"
+  password: "***"
+  url_prefix: "http://localhost:8428"
+
+  # The user for querying account 123 in VictoriaMetrics cluster
+  # See https://github.com/VictoriaMetrics/VictoriaMetrics/blob/cluster/README.md#url-format
+  # All the requests to http://vmauth:8427 with the given Basic Auth (username:password)
+  # will be routed to http://vmselect:8481/select/123/prometheus .
+  # For example, http://vmauth:8427/api/v1/query is routed to http://vmselect:8481/select/123/prometheus/api/v1/select
+- username: "cluster-select-account-123"
+  password: "***"
+  url_prefix: "http://vmselect:8481/select/123/prometheus"
+
+  # The user for inserting Prometheus data into VictoriaMetrics cluster under account 42
+  # See https://github.com/VictoriaMetrics/VictoriaMetrics/blob/cluster/README.md#url-format
+  # All the reuqests to http://vmauth:8427 with the given Basic Auth (username:password)
+  # will be routed to http://vminsert:8480/insert/42/prometheus .
+  # For example, http://vmauth:8427/api/v1/write is routed to http://vminsert:8480/insert/42/prometheus/api/v1/write
+- username: "cluster-insert-account-42"
+  password: "***"
+  url_prefix: "http://vminsert:8480/insert/42/prometheus"
+```
+
+The config may contain `%{ENV_VAR}` placeholders, which are substituted by the corresponding `ENV_VAR` environment variable values.
+This may be useful for passing secrets to the config.
+
+
+### Security
+
+Do not transfer Basic Auth headers in plaintext over untrusted networks. Enable https. This can be done by passing the following `-tls*` command-line flags to `vmauth`:
+
+```
+  -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, since RSA certs are slow
+  -tlsKeyFile string
+    	Path to file with TLS key. Used only if -tls is set
+```
+
+Alternatively, [https termination proxy](https://en.wikipedia.org/wiki/TLS_termination_proxy) may be put in front of `vmauth`.
+
+
+### Monitoring
+
+`vmauth` exports various metrics in Prometheus exposition format at `http://vmauth-host:8427/metrics` page. It is recommended setting up regular scraping of this page
+either via [vmagent](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmagent/README.md) or via Prometheus, so the exported metrics could be analyzed later.
+
+
+### How to build from sources
+
+It is recommended using [binary releases](https://github.com/VictoriaMetrics/VictoriaMetrics/releases) - `vmauth` is located in `vmutils-*` archives there.
+
+
+#### Development build
+
+1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.13.
+2. Run `make vmauth` from the root folder of the repository.
+   It builds `vmauth` binary and puts it into the `bin` folder.
+
+#### Production build
+
+1. [Install docker](https://docs.docker.com/install/).
+2. Run `make vmauth-prod` from the root folder of the repository.
+   It builds `vmauth-prod` binary and puts it into the `bin` folder.
+
+#### Building docker images
+
+Run `make package-vmauth`. It builds `victoriametrics/vmauth:<PKG_TAG>` docker image locally.
+`<PKG_TAG>` is auto-generated image tag, which depends on source code in the repository.
+The `<PKG_TAG>` may be manually set via `PKG_TAG=foobar make package-vmauth`.
+
+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-vmauth
+```
+
+
+### Profiling
+
+`vmauth` provides handlers for collecting the following [Go profiles](https://blog.golang.org/profiling-go-programs):
+
+* Memory profile. It can be collected with the following command:
+
+```bash
+curl -s http://<vmauth-host>:8427/debug/pprof/heap > mem.pprof
+```
+
+* CPU profile. It can be collected with the following command:
+
+```bash
+curl -s http://<vmauth-host>:8427/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
+
+Pass `-help` command-line arg to `vmauth` in order to see all the configuration options:
+
+```
+./vmauth -help
+
+vmauth authenticates and authorizes incoming requests and proxies them to VictoriaMetrics.
+
+See the docs at https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmauth/README.md .
+
+  -auth.config string
+    	Path to auth config. See https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmauth/README.md for details on the format of this auth config
+  -enableTCP6
+    	Whether to enable IPv6 for listening and dialing. By default only IPv4 TCP 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
+  -envflag.prefix string
+    	Prefix for environment variables if -envflag.enable is set
+  -http.connTimeout duration
+    	Incoming http connections are closed after the configured timeout. This may help spreading incoming load among a cluster of services behind load balancer. Note that the real timeout may be bigger by up to 10% as a protection from Thundering herd problem (default 2m0s)
+  -http.disableResponseCompression
+    	Disable compression of HTTP responses for saving 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 graceful shutdown of HTTP server. Highly loaded server may require increased value for 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 dealy the servier 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 (default ":8427")
+  -loggerErrorsPerSecondLimit int
+    	Per-second limit on the number of ERROR messages. If more than the given number of errors are emitted per second, then the remaining errors are suppressed. Zero value disables the rate limit (default 10)
+  -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")
+  -memory.allowedBytes value
+    	Allowed size of system memory VictoriaMetrics caches may occupy. This option overrides -memory.allowedPercent if set to non-zero value. Too low value may increase cache miss rate, which usually results in higher CPU and disk IO usage. Too high value may evict too much data from OS page cache, which will result in higher disk IO usage
+    	Supports the following optional suffixes for 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 value may increase cache miss rate, which usually results in higher CPU and disk IO usage. Too high 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
+  -pprofAuthKey string
+    	Auth key for /debug/pprof. It overrides httpAuth settings
+  -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, since RSA certs are slow
+  -tlsKeyFile string
+    	Path to file with TLS key. Used only if -tls is set
+  -version
+    	Show VictoriaMetrics version
+```

app/vmauth/auth_config.go

@@ -0,0 +1,131 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"net/url"
+	"strings"
+	"sync"
+	"sync/atomic"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envtemplate"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
+	"github.com/VictoriaMetrics/metrics"
+	"gopkg.in/yaml.v2"
+)
+
+var (
+	authConfigPath = flag.String("auth.config", "", "Path to auth config. See https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmauth/README.md "+
+		"for details on the format of this auth config")
+)
+
+// AuthConfig represents auth config.
+type AuthConfig struct {
+	Users []UserInfo `yaml:"users"`
+}
+
+// UserInfo is user information read from authConfigPath
+type UserInfo struct {
+	Username  string `yaml:"username"`
+	Password  string `yaml:"password"`
+	URLPrefix string `yaml:"url_prefix"`
+
+	requests *metrics.Counter
+}
+
+func initAuthConfig() {
+	if len(*authConfigPath) == 0 {
+		logger.Fatalf("missing required `-auth.config` command-line flag")
+	}
+	m, err := readAuthConfig(*authConfigPath)
+	if err != nil {
+		logger.Fatalf("cannot load auth config from `-auth.config=%s`: %s", *authConfigPath, err)
+	}
+	authConfig.Store(m)
+	stopCh = make(chan struct{})
+	authConfigWG.Add(1)
+	go func() {
+		defer authConfigWG.Done()
+		authConfigReloader()
+	}()
+}
+
+func stopAuthConfig() {
+	close(stopCh)
+	authConfigWG.Wait()
+}
+
+func authConfigReloader() {
+	sighupCh := procutil.NewSighupChan()
+	for {
+		select {
+		case <-stopCh:
+			return
+		case <-sighupCh:
+			logger.Infof("SIGHUP received; loading -auth.config=%q", *authConfigPath)
+			m, err := readAuthConfig(*authConfigPath)
+			if err != nil {
+				logger.Errorf("failed to load -auth.config=%q; using the last successfully loaded config; error: %s", *authConfigPath, err)
+				continue
+			}
+			authConfig.Store(m)
+			logger.Infof("Successfully reloaded -auth.config=%q", *authConfigPath)
+		}
+	}
+}
+
+var authConfig atomic.Value
+var authConfigWG sync.WaitGroup
+var stopCh chan struct{}
+
+func readAuthConfig(path string) (map[string]*UserInfo, error) {
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("cannot read %q: %w", path, err)
+	}
+	m, err := parseAuthConfig(data)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse %q: %w", path, err)
+	}
+	logger.Infof("Loaded information about %d users from %q", len(m), path)
+	return m, nil
+}
+
+func parseAuthConfig(data []byte) (map[string]*UserInfo, error) {
+	data = envtemplate.Replace(data)
+	var ac AuthConfig
+	if err := yaml.UnmarshalStrict(data, &ac); err != nil {
+		return nil, fmt.Errorf("cannot unmarshal AuthConfig data: %w", err)
+	}
+	uis := ac.Users
+	if len(uis) == 0 {
+		return nil, fmt.Errorf("`users` section cannot be empty in AuthConfig")
+	}
+	m := make(map[string]*UserInfo, len(uis))
+	for i := range uis {
+		ui := &uis[i]
+		if m[ui.Username] != nil {
+			return nil, fmt.Errorf("duplicate username found; username: %q", ui.Username)
+		}
+		urlPrefix := ui.URLPrefix
+		// Remove trailing '/' from urlPrefix
+		for strings.HasSuffix(urlPrefix, "/") {
+			urlPrefix = urlPrefix[:len(urlPrefix)-1]
+		}
+		// Validate urlPrefix
+		target, err := url.Parse(urlPrefix)
+		if err != nil {
+			return nil, fmt.Errorf("invalid `url_prefix: %q`: %w", urlPrefix, err)
+		}
+		if target.Scheme != "http" && target.Scheme != "https" {
+			return nil, fmt.Errorf("unsupported scheme for `url_prefix: %q`: %q; must be `http` or `https`", urlPrefix, target.Scheme)
+		}
+
+		ui.URLPrefix = urlPrefix
+		ui.requests = metrics.GetOrCreateCounter(fmt.Sprintf(`vmauth_user_requests_total{username=%q}`, ui.Username))
+		m[ui.Username] = ui
+	}
+	return m, nil
+}

app/vmauth/auth_config_test.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestParseAuthConfigFailure(t *testing.T) {
+	f := func(s string) {
+		t.Helper()
+		_, err := parseAuthConfig([]byte(s))
+		if err == nil {
+			t.Fatalf("expecting non-nil error")
+		}
+	}
+
+	// Empty config
+	f(``)
+
+	// Invalid entry
+	f(`foobar`)
+	f(`foobar: baz`)
+
+	// Empty users
+	f(`users: []`)
+
+	// Missing url_prefix
+	f(`
+users:
+- username: foo
+`)
+
+	// Invalid url_prefix
+	f(`
+users:
+- username: foo
+  url_prefix: bar
+`)
+	f(`
+users:
+- username: foo
+  url_prefix: ftp://bar
+`)
+	f(`
+users:
+- username: foo
+  url_prefix: //bar
+`)
+
+	// Duplicate users
+	f(`
+users:
+- username: foo
+  url_prefix: http://foo.bar
+- username: bar
+  url_prefix: http://xxx.yyy
+- username: foo
+  url_prefix: https://sss.sss
+`)
+}
+
+func TestParseAuthConfigSuccess(t *testing.T) {
+	f := func(s string, expectedAuthConfig map[string]*UserInfo) {
+		t.Helper()
+		m, err := parseAuthConfig([]byte(s))
+		if err != nil {
+			t.Fatalf("unexpected error: %s", err)
+		}
+		removeMetrics(m)
+		if !reflect.DeepEqual(m, expectedAuthConfig) {
+			t.Fatalf("unexpected auth config\ngot\n%v\nwant\n%v", m, expectedAuthConfig)
+		}
+	}
+
+	// Single user
+	f(`
+users:
+- username: foo
+  password: bar
+  url_prefix: http://aaa:343/bbb
+`, map[string]*UserInfo{
+		"foo": {
+			Username:  "foo",
+			Password:  "bar",
+			URLPrefix: "http://aaa:343/bbb",
+		},
+	})
+
+	// Multiple users
+	f(`
+users:
+- username: foo
+  url_prefix: http://foo
+- username: bar
+  url_prefix: https://bar/x///
+`, map[string]*UserInfo{
+		"foo": {
+			Username:  "foo",
+			URLPrefix: "http://foo",
+		},
+		"bar": {
+			Username:  "bar",
+			URLPrefix: "https://bar/x",
+		},
+	})
+}
+
+func removeMetrics(m map[string]*UserInfo) {
+	for _, info := range m {
+		info.requests = nil
+	}
+}

app/vmauth/deployment/Dockerfile

@@ -0,0 +1,8 @@
+ARG base_image
+FROM $base_image
+
+EXPOSE 8427
+
+ENTRYPOINT ["/vmauth-prod"]
+ARG src_binary
+COPY $src_binary ./vmauth-prod

app/vmauth/example_config.yml

@@ -0,0 +1,31 @@
+# Arbitrary number of usernames may be put here.
+# Usernames must be unique.
+
+users:
+
+  # The user for querying local single-node VictoriaMetrics.
+  # All the requests to http://vmauth:8427 with the given Basic Auth (username:password)
+  # will be routed to http://localhost:8428 .
+  # For example, http://vmauth:8427/api/v1/query is routed to http://localhost:8428/api/v1/query
+- username: "local-single-node"
+  password: "***"
+  url_prefix: "http://localhost:8428"
+
+  # The user for querying account 123 in VictoriaMetrics cluster
+  # See https://github.com/VictoriaMetrics/VictoriaMetrics/blob/cluster/README.md#url-format
+  # All the requests to http://vmauth:8427 with the given Basic Auth (username:password)
+  # will be routed to http://vmselect:8481/select/123/prometheus .
+  # For example, http://vmauth:8427/api/v1/query is routed to http://vmselect:8481/select/123/prometheus/api/v1/select
+- username: "cluster-select-account-123"
+  password: "***"
+  url_prefix: "http://vmselect:8481/select/123/prometheus"
+
+  # The user for inserting Prometheus data into VictoriaMetrics cluster under account 42
+  # See https://github.com/VictoriaMetrics/VictoriaMetrics/blob/cluster/README.md#url-format
+  # All the reuqests to http://vmauth:8427 with the given Basic Auth (username:password)
+  # will be routed to http://vminsert:8480/insert/42/prometheus .
+  # For example, http://vmauth:8427/api/v1/write is routed to http://vminsert:8480/insert/42/prometheus/api/v1/write
+- username: "cluster-insert-account-42"
+  password: "***"
+  url_prefix: "http://vminsert:8480/insert/42/prometheus"
+

app/vmauth/main.go

@@ -0,0 +1,107 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"os"
+	"time"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/buildinfo"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envflag"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
+)
+
+var (
+	httpListenAddr = flag.String("httpListenAddr", ":8427", "TCP address to listen for http connections")
+)
+
+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()
+	cgroup.UpdateGOMAXPROCSToCPUQuota()
+	logger.Infof("starting vmauth at %q...", *httpListenAddr)
+	startTime := time.Now()
+	initAuthConfig()
+	go httpserver.Serve(*httpListenAddr, requestHandler)
+	logger.Infof("started vmauth in %.3f seconds", time.Since(startTime).Seconds())
+
+	sig := procutil.WaitForSigterm()
+	logger.Infof("received signal %s", sig)
+
+	startTime = time.Now()
+	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())
+	stopAuthConfig()
+	logger.Infof("successfully stopped vmauth in %.3f seconds", time.Since(startTime).Seconds())
+}
+
+func requestHandler(w http.ResponseWriter, r *http.Request) bool {
+	username, password, ok := r.BasicAuth()
+	if !ok {
+		w.Header().Set("WWW-Authenticate", `Basic realm="Restricted"`)
+		http.Error(w, "missing `Authorization: Basic *` header", http.StatusUnauthorized)
+		return true
+	}
+	ac := authConfig.Load().(map[string]*UserInfo)
+	info := ac[username]
+	if info == nil || info.Password != password {
+		httpserver.Errorf(w, r, "cannot find the provided username %q or password in config", username)
+		return true
+	}
+	info.requests.Inc()
+
+	targetURL := createTargetURL(info.URLPrefix, r.URL)
+	if _, err := url.Parse(targetURL); err != nil {
+		httpserver.Errorf(w, r, "invalid targetURL=%q: %s", targetURL, err)
+		return true
+	}
+	r.Header.Set("vm-target-url", targetURL)
+	reverseProxy.ServeHTTP(w, r)
+	return true
+}
+
+var reverseProxy = &httputil.ReverseProxy{
+	Director: func(r *http.Request) {
+		targetURL := r.Header.Get("vm-target-url")
+		target, err := url.Parse(targetURL)
+		if err != nil {
+			logger.Panicf("BUG: unexpected error when parsing targetURL=%q: %s", targetURL, err)
+		}
+		r.URL = target
+	},
+	Transport: func() *http.Transport {
+		tr := http.DefaultTransport.(*http.Transport).Clone()
+		// Automatic compression must be disabled in order to fix https://github.com/VictoriaMetrics/VictoriaMetrics/issues/535
+		tr.DisableCompression = true
+		// Disable HTTP/2.0, since VictoriaMetrics components don't support HTTP/2.0 (because there is no sense in this).
+		tr.ForceAttemptHTTP2 = false
+		return tr
+	}(),
+	FlushInterval: time.Second,
+	ErrorLog:      logger.StdErrorLogger(),
+}
+
+func usage() {
+	const s = `
+vmauth authenticates and authorizes incoming requests and proxies them to VictoriaMetrics.
+
+See the docs at https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmauth/README.md .
+`
+
+	f := flag.CommandLine.Output()
+	fmt.Fprintf(f, "%s\n", s)
+	flag.PrintDefaults()
+}

app/vmauth/target_url.go

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"net/url"
+	"path"
+	"strings"
+)
+
+func createTargetURL(prefix string, u *url.URL) string {
+	// Prevent from attacks with using `..` in r.URL.Path
+	u.Path = path.Clean(u.Path)
+	if !strings.HasPrefix(u.Path, "/") {
+		u.Path = "/" + u.Path
+	}
+	return prefix + u.RequestURI()
+}