lib/promscrape: ignore proxies for Unix socket targets

Unix socket scrape targets inherit `http.DefaultTransport.Proxy` through
`httputil.NewTransport`. When proxy environment variables are
configured, HTTP requests over Unix sockets are altered as proxy
requests, while HTTPS scrapes send `CONNECT` to the Unix socket and fail
the TLS handshake.

Unix sockets are explicit local transport endpoints and cannot be
reached through HTTP proxies. Clear the transport proxy for targets
configured with `__unix_socket__`, matching the existing rejection of
`proxy_url` for these targets.
The bug was introduced with Unix socket scraping support in v1.148.0  at https://github.com/VictoriaMetrics/VictoriaMetrics/pull/11193

Related PR https://github.com/VictoriaMetrics/VictoriaMetrics/pull/11318

README.md

@@ -2,7 +2,6 @@
 
 [![Latest Release](https://img.shields.io/github/v/release/VictoriaMetrics/VictoriaMetrics?sort=semver&label=&filter=!*-victorialogs&logo=github&labelColor=gray&color=gray&link=https%3A%2F%2Fgithub.com%2FVictoriaMetrics%2FVictoriaMetrics%2Freleases%2Flatest)](https://github.com/VictoriaMetrics/VictoriaMetrics/releases)
 [![Docker Pulls](https://img.shields.io/docker/pulls/victoriametrics/victoria-metrics?label=&logo=docker&logoColor=white&labelColor=2496ED&color=2496ED&link=https%3A%2F%2Fhub.docker.com%2Fr%2Fvictoriametrics%2Fvictoria-metrics)](https://hub.docker.com/u/victoriametrics)
-[![Go Report](https://goreportcard.com/badge/github.com/VictoriaMetrics/VictoriaMetrics?link=https%3A%2F%2Fgoreportcard.com%2Freport%2Fgithub.com%2FVictoriaMetrics%2FVictoriaMetrics)](https://goreportcard.com/report/github.com/VictoriaMetrics/VictoriaMetrics)
 [![Build Status](https://github.com/VictoriaMetrics/VictoriaMetrics/actions/workflows/build.yml/badge.svg?branch=master&link=https%3A%2F%2Fgithub.com%2FVictoriaMetrics%2FVictoriaMetrics%2Factions)](https://github.com/VictoriaMetrics/VictoriaMetrics/actions/workflows/build.yml)
 [![License](https://img.shields.io/github/license/VictoriaMetrics/VictoriaMetrics?labelColor=green&label=&link=https%3A%2F%2Fgithub.com%2FVictoriaMetrics%2FVictoriaMetrics%2Fblob%2Fmaster%2FLICENSE)](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/LICENSE)
 [![Join Slack](https://img.shields.io/badge/Join%20Slack-4A154B?logo=slack)](https://slack.victoriametrics.com)

app/vmalert/datasource/client.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/netutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promauth"
@@ -267,7 +268,11 @@ func (c *Client) do(req *http.Request) (*http.Response, error) {
 	if resp.StatusCode != http.StatusOK {
 		body, _ := io.ReadAll(resp.Body)
 		_ = resp.Body.Close()
-		return nil, fmt.Errorf("unexpected response code %d for %s. Response body %s", resp.StatusCode, ru, body)
+		err = &httpserver.ErrorWithStatusCode{
+			StatusCode: resp.StatusCode,
+			Err:        fmt.Errorf("unexpected response code %d for %s. Response body %s", resp.StatusCode, ru, body),
+		}
+		return nil, err
 	}
 	return resp, nil
 }

app/vmalert/notifier/alert.go

@@ -31,6 +31,8 @@ type Alert struct {
 	State AlertState
 	// Expr contains expression that was executed to generate the Alert
 	Expr string
+	// Interval contains the evaluation interval of the Alert's group
+	Interval time.Duration
 	// ActiveAt defines the moment of time when Alert has become active
 	ActiveAt time.Time
 	// Start defines the moment of time when Alert has become firing
@@ -84,6 +86,7 @@ type AlertTplData struct {
 	Labels    map[string]string
 	Value     float64
 	Expr      string
+	Interval  time.Duration
 	AlertID   uint64
 	GroupID   uint64
 	ActiveAt  time.Time
@@ -96,6 +99,7 @@ var tplHeaders = []string{
 	"{{ $type := .Type }}",
 	"{{ $labels := .Labels }}",
 	"{{ $expr := .Expr }}",
+	"{{ $interval := .Interval }}",
 	"{{ $externalLabels := .ExternalLabels }}",
 	"{{ $externalURL := .ExternalURL }}",
 	"{{ $alertID := .AlertID }}",
@@ -115,6 +119,7 @@ func (a *Alert) ExecTemplate(q templates.QueryFn, labels, annotations map[string
 		Type:     a.Type,
 		Labels:   labels,
 		Expr:     a.Expr,
+		Interval: a.Interval,
 		AlertID:  a.ID,
 		GroupID:  a.GroupID,
 		ActiveAt: a.ActiveAt,

app/vmalert/notifier/alert_test.go

@@ -129,6 +129,17 @@ func TestAlertExecTemplate(t *testing.T) {
 		"exprEscapedHTML":   "vm_rows{"label"="bar"}<0",
 	})
 
+	// interval-template
+	f(&Alert{
+		Interval: 10 * time.Second,
+	}, map[string]string{
+		"interval":         "{{ .Interval }}",
+		"intervalVariable": "{{ $interval }}",
+	}, map[string]string{
+		"interval":         "10s",
+		"intervalVariable": "10s",
+	})
+
 	// query
 	f(&Alert{
 		Expr: `vm_rows{"label"="bar"}>0`,

app/vmalert/replay.go

@@ -25,11 +25,12 @@ var (
 	replayMaxDatapoints = flag.Int("replay.maxDatapointsPerQuery", 1e3,
 		"Max number of data points expected in one request. It affects the max time range for every '/query_range' request during the replay. The higher the value, the less requests will be made during replay.")
 	replayRuleRetryAttempts = flag.Int("replay.ruleRetryAttempts", 5,
-		"Defines how many retries to make before giving up on rule if request for it returns an error.")
+		"Defines how many retries to make before giving up on rule if request for it returns a retriable error.")
 	disableProgressBar = flag.Bool("replay.disableProgressBar", false, "Whether to disable rendering progress bars during the replay. "+
 		"Progress bar rendering might be verbose or break the logs parsing, so it is recommended to be disabled when not used in interactive mode.")
 	ruleEvaluationConcurrency = flag.Int("replay.ruleEvaluationConcurrency", 1, "The maximum number of concurrent '/query_range' requests when replay recording rule or alerting rule with for=0. "+
 		"Increasing this value when replaying for a long time, since each request is limited by -replay.maxDatapointsPerQuery.")
+	continueWithExecutionErr = flag.Bool("replay.continueWithExecutionErr", false, "Whether to continue replaying other rules if a rule execution fails with a 422 response code, which can happen due to an expression syntax error or a resource limit being hit.")
 )
 
 func replay(groupsCfg []config.Group, qb datasource.QuerierBuilder, rw remotewrite.RWClient) (totalRows, droppedRows int, err error) {
@@ -73,7 +74,7 @@ func replay(groupsCfg []config.Group, qb datasource.QuerierBuilder, rw remotewri
 
 	for _, cfg := range groupsCfg {
 		ng := rule.NewGroup(cfg, qb, *evaluationInterval, labels)
-		totalRows += ng.Replay(tFrom, tTo, rw, *replayMaxDatapoints, *replayRuleRetryAttempts, *replayRulesDelay, *disableProgressBar, *ruleEvaluationConcurrency)
+		totalRows += ng.Replay(tFrom, tTo, rw, *replayMaxDatapoints, *replayRuleRetryAttempts, *replayRulesDelay, *disableProgressBar, *ruleEvaluationConcurrency, *continueWithExecutionErr)
 	}
 	logger.Infof("replay evaluation finished, generated %d samples", totalRows)
 	if err := rw.Close(); err != nil {

app/vmalert/replay_test.go

@@ -8,8 +8,10 @@ import (
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/config"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompb"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/promutil"
+	"github.com/VictoriaMetrics/metricsql"
 )
 
 type fakeReplayQuerier struct {
@@ -32,6 +34,14 @@ func (fc *fakeRWClient) Close() error {
 }
 
 func (fr *fakeReplayQuerier) QueryRange(_ context.Context, q string, from, to time.Time) (res datasource.Result, err error) {
+	_, err = metricsql.Parse(q)
+	if err != nil {
+		return res, &httpserver.ErrorWithStatusCode{
+			StatusCode: 422,
+			Err:        err,
+		}
+	}
+
 	key := fmt.Sprintf("%s+%s", from.Format("15:04:05"), to.Format("15:04:05"))
 	dps, ok := fr.registry[q]
 	if !ok {
@@ -275,4 +285,28 @@ func TestReplay(t *testing.T) {
 			},
 		},
 	}, 10)
+
+	// rule with wrong expression won't break the other rule with continueWithExecutionErr
+	continueWithExecutionErrOld := *continueWithExecutionErr
+	defer func() {
+		*continueWithExecutionErr = continueWithExecutionErrOld
+	}()
+	*continueWithExecutionErr = true
+	f("2021-01-01T12:00:00.000Z", "2021-01-01T12:02:30.000Z", 1, 1, time.Millisecond, []config.Group{
+		{Rules: []config.Rule{{Record: "foo", Expr: "sum(up)"}}},
+		{Rules: []config.Rule{{Record: "bar", Expr: "up ++"}}},
+	}, &fakeReplayQuerier{
+		registry: map[string]map[string][]datasource.Metric{
+			"sum(up)": {
+				"12:00:00+12:01:00": {
+					{
+						Timestamps: []int64{1, 2},
+						Values:     []float64{1, 2},
+					},
+				},
+				"12:01:00+12:02:00": {},
+				"12:02:00+12:02:30": {},
+			},
+		},
+	}, 2)
 }

app/vmalert/rule/alerting.go

@@ -530,6 +530,7 @@ func (ar *AlertingRule) exec(ctx context.Context, ts time.Time, limit int) ([]pr
 				ar.logDebugf(ts, a, "INACTIVE => PENDING")
 			}
 			a.Value = m.Values[0]
+			a.Interval = ar.EvalInterval
 			a.Annotations = annotations
 			a.KeepFiringSince = time.Time{}
 			continue
@@ -612,6 +613,7 @@ func (ar *AlertingRule) expandAnnotationTemplates(m datasource.Metric, qFn templ
 		Type:      ar.Type.String(),
 		Labels:    ls.origin,
 		Expr:      ar.Expr,
+		Interval:  ar.EvalInterval,
 		AlertID:   hash(ls.processed),
 		GroupID:   ar.GroupID,
 		ActiveAt:  activeAt,
@@ -673,6 +675,7 @@ func (ar *AlertingRule) newAlert(m datasource.Metric, start time.Time, labels, a
 		Name:        ar.Name,
 		Type:        ar.Type.String(),
 		Expr:        ar.Expr,
+		Interval:    ar.EvalInterval,
 		For:         ar.For,
 		ActiveAt:    start,
 		Value:       m.Values[0],

app/vmalert/rule/alerting_test.go

@@ -662,6 +662,7 @@ func TestAlertingRuleExecRange(t *testing.T) {
 			GroupID:     fakeGroup.GetID(),
 			Name:        "for-pending",
 			Type:        config.NewPrometheusType().String(),
+			Interval:    time.Second,
 			Labels:      map[string]string{"alertname": "for-pending"},
 			Annotations: map[string]string{},
 			State:       notifier.StatePending,
@@ -682,6 +683,7 @@ func TestAlertingRuleExecRange(t *testing.T) {
 			GroupID:     fakeGroup.GetID(),
 			Name:        "for-firing",
 			Type:        config.NewPrometheusType().String(),
+			Interval:    3 * time.Second,
 			Labels:      map[string]string{"alertname": "for-firing"},
 			Annotations: map[string]string{},
 			State:       notifier.StateFiring,
@@ -703,6 +705,7 @@ func TestAlertingRuleExecRange(t *testing.T) {
 			GroupID:     fakeGroup.GetID(),
 			Name:        "for-hold-pending",
 			Type:        config.NewPrometheusType().String(),
+			Interval:    time.Second,
 			Labels:      map[string]string{"alertname": "for-hold-pending"},
 			Annotations: map[string]string{},
 			State:       notifier.StatePending,
@@ -759,6 +762,7 @@ func TestAlertingRuleExecRange(t *testing.T) {
 			GroupID:     fakeGroup.GetID(),
 			Name:        "multi-series",
 			Type:        config.NewPrometheusType().String(),
+			Interval:    3 * time.Second,
 			Labels:      map[string]string{"alertname": "multi-series"},
 			Annotations: map[string]string{},
 			State:       notifier.StateFiring,
@@ -771,6 +775,7 @@ func TestAlertingRuleExecRange(t *testing.T) {
 			GroupID:     fakeGroup.GetID(),
 			Name:        "multi-series",
 			Type:        config.NewPrometheusType().String(),
+			Interval:    3 * time.Second,
 			Labels:      map[string]string{"alertname": "multi-series", "foo": "bar"},
 			Annotations: map[string]string{},
 			State:       notifier.StatePending,
@@ -1134,7 +1139,8 @@ func TestAlertingRule_Template(t *testing.T) {
 		fq.Add(metrics...)
 		fq.SetPartialResponse(isResponsePartial)
 
-		if _, err := rule.exec(context.TODO(), time.Now(), 0); err != nil {
+		ts := time.Unix(3600, 0)
+		if _, err := rule.exec(context.TODO(), ts, 0); err != nil {
 			t.Fatalf("unexpected error: %s", err)
 		}
 		for hash, expAlert := range alertsExpected {
@@ -1152,12 +1158,14 @@ func TestAlertingRule_Template(t *testing.T) {
 	}
 
 	f(&AlertingRule{
-		Name: "common",
+		Name:         "common",
+		EvalInterval: time.Hour,
 		Labels: map[string]string{
 			"region": "east",
 		},
 		Annotations: map[string]string{
-			"summary": `{{ $labels.alertname }}: Too high connection number for "{{ $labels.instance }}"`,
+			"summary":   `{{ $labels.alertname }}: Too high connection number for "{{ $labels.instance }}"`,
+			"dashboard": `&from={{ ($activeAt.Add (parseDurationTime (printf "-%s" .Interval))).UnixMilli }}&to={{ $activeAt.UnixMilli }}`,
 		},
 		alerts: make(map[uint64]*notifier.Alert),
 	}, []datasource.Metric{
@@ -1166,7 +1174,8 @@ func TestAlertingRule_Template(t *testing.T) {
 	}, false, map[uint64]*notifier.Alert{
 		hash(map[string]string{alertNameLabel: "common", "region": "east", "instance": "foo"}): {
 			Annotations: map[string]string{
-				"summary": `common: Too high connection number for "foo"`,
+				"summary":   `common: Too high connection number for "foo"`,
+				"dashboard": "&from=0&to=3600000",
 			},
 			Labels: map[string]string{
 				alertNameLabel: "common",
@@ -1176,7 +1185,8 @@ func TestAlertingRule_Template(t *testing.T) {
 		},
 		hash(map[string]string{alertNameLabel: "common", "region": "east", "instance": "bar"}): {
 			Annotations: map[string]string{
-				"summary": `common: Too high connection number for "bar"`,
+				"summary":   `common: Too high connection number for "bar"`,
+				"dashboard": "&from=0&to=3600000",
 			},
 			Labels: map[string]string{
 				alertNameLabel: "common",
@@ -1388,7 +1398,7 @@ func TestAlertingRule_ToLabels(t *testing.T) {
 		"alertname":     "ConfigurationReloadFailure",
 		"alertgroup":    "vmalert",
 		"pod":           "vmalert-0",
-		"invalid_label": `error evaluating template: template: :1:298: executing "" at <.Values.mustRuntimeFail>: can't evaluate field Values in type notifier.tplData`,
+		"invalid_label": `error evaluating template: template: :1:326: executing "" at <.Values.mustRuntimeFail>: can't evaluate field Values in type notifier.tplData`,
 	}
 
 	expectedProcessedLabels := map[string]string{
@@ -1398,7 +1408,7 @@ func TestAlertingRule_ToLabels(t *testing.T) {
 		"exported_alertname": "ConfigurationReloadFailure",
 		"group":              "vmalert",
 		"alertgroup":         "vmalert",
-		"invalid_label":      `error evaluating template: template: :1:298: executing "" at <.Values.mustRuntimeFail>: can't evaluate field Values in type notifier.tplData`,
+		"invalid_label":      `error evaluating template: template: :1:326: executing "" at <.Values.mustRuntimeFail>: can't evaluate field Values in type notifier.tplData`,
 	}
 
 	ls, err := ar.toLabels(metric, nil)

app/vmalert/rule/group.go

@@ -548,7 +548,7 @@ func (g *Group) infof(format string, args ...any) {
 }
 
 // Replay performs group replay
-func (g *Group) Replay(start, end time.Time, rw remotewrite.RWClient, maxDataPoint, replayRuleRetryAttempts int, replayDelay time.Duration, disableProgressBar bool, ruleEvaluationConcurrency int) int {
+func (g *Group) Replay(start, end time.Time, rw remotewrite.RWClient, maxDataPoint, replayRuleRetryAttempts int, replayDelay time.Duration, disableProgressBar bool, ruleEvaluationConcurrency int, continueWithExecutionErr bool) int {
 	var total int
 	step := g.Interval * time.Duration(maxDataPoint)
 	ri := rangeIterator{start: start, end: end, step: step}
@@ -576,7 +576,7 @@ func (g *Group) Replay(start, end time.Time, rw remotewrite.RWClient, maxDataPoi
 			if !disableProgressBar {
 				bar = pb.StartNew(iterations)
 			}
-			total += replayRuleRange(rule, ri, bar, rw, replayRuleRetryAttempts, ruleEvaluationConcurrency)
+			total += replayRuleRange(rule, ri, bar, rw, replayRuleRetryAttempts, ruleEvaluationConcurrency, continueWithExecutionErr)
 			if bar != nil {
 				bar.Finish()
 			}
@@ -598,7 +598,7 @@ func (g *Group) Replay(start, end time.Time, rw remotewrite.RWClient, maxDataPoi
 		rule := g.Rules[i]
 		sem <- struct{}{}
 		wg.Go(func() {
-			res <- replayRuleRange(rule, ri, bar, rw, replayRuleRetryAttempts, ruleEvaluationConcurrency)
+			res <- replayRuleRange(rule, ri, bar, rw, replayRuleRetryAttempts, ruleEvaluationConcurrency, continueWithExecutionErr)
 			<-sem
 		})
 	}
@@ -618,7 +618,7 @@ func (g *Group) Replay(start, end time.Time, rw remotewrite.RWClient, maxDataPoi
 	return total
 }
 
-func replayRuleRange(r Rule, ri rangeIterator, bar *pb.ProgressBar, rw remotewrite.RWClient, replayRuleRetryAttempts, ruleEvaluationConcurrency int) int {
+func replayRuleRange(r Rule, ri rangeIterator, bar *pb.ProgressBar, rw remotewrite.RWClient, replayRuleRetryAttempts, ruleEvaluationConcurrency int, continueWithExecutionErr bool) int {
 	fmt.Printf("> Rule %q (ID: %d)\n", r, r.ID())
 	// alerting rule with for>0 can't be replayed concurrently, since the status change might depend on the previous evaluation
 	// see https://github.com/VictoriaMetrics/VictoriaMetrics/commit/abcb21aa5ee918ba9a4e9cde495dba06e1e9564c
@@ -633,7 +633,7 @@ func replayRuleRange(r Rule, ri rangeIterator, bar *pb.ProgressBar, rw remotewri
 		start := ri.s
 		end := ri.e
 		wg.Go(func() {
-			n, err := replayRule(r, start, end, rw, replayRuleRetryAttempts)
+			n, err := replayRule(r, start, end, rw, replayRuleRetryAttempts, continueWithExecutionErr)
 			if err != nil {
 				logger.Fatalf("rule %q: %s", r, err)
 			}

app/vmalert/rule/rule.go

@@ -4,12 +4,14 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"net/http"
 	"sync"
 	"time"
 
 	"github.com/VictoriaMetrics/metrics"
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/remotewrite"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompb"
 )
@@ -118,7 +120,7 @@ func (s *ruleState) add(e StateEntry) {
 	s.entries[s.cur] = e
 }
 
-func replayRule(r Rule, start, end time.Time, rw remotewrite.RWClient, replayRuleRetryAttempts int) (int, error) {
+func replayRule(r Rule, start, end time.Time, rw remotewrite.RWClient, replayRuleRetryAttempts int, continueWithExecutionErr bool) (int, error) {
 	var err error
 	var tss []prompb.TimeSeries
 	for i := range replayRuleRetryAttempts {
@@ -126,6 +128,21 @@ func replayRule(r Rule, start, end time.Time, rw remotewrite.RWClient, replayRul
 		if err == nil {
 			break
 		}
+		// retry request if possible to tolerate temporary network or datasource unavailability issues
+		var esc *httpserver.ErrorWithStatusCode
+		if errors.As(err, &esc) {
+			statusCode := esc.StatusCode
+			// if the status code is 422, it means that the query was executed but failed due to an expression syntax error or a the resource limit being hit,
+			// continue replaying but skip the problematic execution if continueWithExecutionErr is true, otherwise, return the error without retry.
+			if statusCode == http.StatusUnprocessableEntity {
+				if continueWithExecutionErr {
+					logger.Errorf("rule %q: %s", r, err)
+					return 0, nil
+				} else {
+					return 0, err
+				}
+			}
+		}
 		logger.Errorf("attempt %d to execute rule %q failed: %s", i+1, r, err)
 		time.Sleep(time.Second)
 	}

app/vmctl/remoteread/remoteread.go

@@ -8,12 +8,14 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"strconv"
 	"strings"
 	"time"
 
 	"github.com/gogo/protobuf/proto"
 	"github.com/golang/snappy"
 	"github.com/prometheus/prometheus/config"
+	"github.com/prometheus/prometheus/model/histogram"
 	"github.com/prometheus/prometheus/prompb"
 	"github.com/prometheus/prometheus/storage/remote"
 	"github.com/prometheus/prometheus/tsdb/chunkenc"
@@ -234,9 +236,29 @@ func processResponse(body io.ReadCloser, callback StreamCallback) error {
 	// shouldn't be accounted as an error.
 	for _, res := range readResp.Results {
 		for _, ts := range res.Timeseries {
-			vmTs := convertSamples(ts.Samples, ts.Labels)
-			if err := callback(vmTs); err != nil {
-				return err
+			// A series contains either float samples or native histogram samples.
+			// Both fields are processed independently, since a series may switch
+			// from float to native histogram representation at some point in time,
+			// so the requested time range may contain samples of both types.
+			if len(ts.Samples) > 0 {
+				vmTs := convertSamples(ts.Samples, ts.Labels)
+				if err := callback(vmTs); err != nil {
+					return err
+				}
+			}
+			if len(ts.Histograms) > 0 {
+				hSamples := make([]histogramSample, 0, len(ts.Histograms))
+				for _, h := range ts.Histograms {
+					hSamples = append(hSamples, histogramSample{
+						timestamp: h.Timestamp,
+						fh:        h.ToFloatHistogram(),
+					})
+				}
+				for _, vmTs := range convertHistograms(hSamples, ts.Labels) {
+					if err := callback(vmTs); err != nil {
+						return err
+					}
+				}
 			}
 		}
 	}
@@ -263,17 +285,45 @@ func processStreamResponse(body io.ReadCloser, callback StreamCallback) error {
 
 		for _, series := range res.ChunkedSeries {
 			samples := make([]prompb.Sample, 0)
+			var hSamples []histogramSample
 			for _, chunk := range series.Chunks {
-				s, err := parseSamples(chunk.Data)
-				if err != nil {
-					return err
+				switch chunk.Type {
+				case prompb.Chunk_XOR, prompb.Chunk_UNKNOWN:
+					// In proto3 the `type` field may be left unset (UNKNOWN) for XOR chunks.
+					// Prometheus remote.proto: "REQUIREMENT: when using proto3, this field
+					// MUST be set when using anything else than XOR". Senders before native
+					// histograms support (Prometheus < 2.40) do not set this field at all,
+					// so UNKNOWN chunks must be parsed as XOR ones.
+					s, err := parseSamples(chunk.Data)
+					if err != nil {
+						return err
+					}
+					samples = append(samples, s...)
+				case prompb.Chunk_HISTOGRAM, prompb.Chunk_FLOAT_HISTOGRAM:
+					hs, err := parseHistograms(chunk.Type, chunk.Data)
+					if err != nil {
+						return err
+					}
+					hSamples = append(hSamples, hs...)
+				default:
+					return fmt.Errorf("unsupported chunk encoding %q", chunk.Type)
 				}
-				samples = append(samples, s...)
 			}
 
-			ts := convertSamples(samples, series.Labels)
-			if err := callback(ts); err != nil {
-				return err
+			// A series contains either XOR chunks or native histogram chunks.
+			// Both are processed independently, since a series may switch
+			// from float to native histogram representation at some point in time,
+			// so the requested time range may contain chunks of both types.
+			if len(samples) > 0 {
+				ts := convertSamples(samples, series.Labels)
+				if err := callback(ts); err != nil {
+					return err
+				}
+			}
+			for _, ts := range convertHistograms(hSamples, series.Labels) {
+				if err := callback(ts); err != nil {
+					return err
+				}
 			}
 		}
 	}
@@ -312,6 +362,151 @@ func parseSamples(chunk []byte) ([]prompb.Sample, error) {
 	return samples, it.Err()
 }
 
+// histogramSample represents a single native histogram sample.
+type histogramSample struct {
+	timestamp int64
+	fh        *histogram.FloatHistogram
+}
+
+func parseHistograms(encoding prompb.Chunk_Encoding, chunk []byte) ([]histogramSample, error) {
+	var enc chunkenc.Encoding
+	switch encoding {
+	case prompb.Chunk_HISTOGRAM:
+		enc = chunkenc.EncHistogram
+	case prompb.Chunk_FLOAT_HISTOGRAM:
+		enc = chunkenc.EncFloatHistogram
+	default:
+		return nil, fmt.Errorf("unsupported histogram chunk encoding %q", encoding)
+	}
+	c, err := chunkenc.FromData(enc, chunk)
+	if err != nil {
+		return nil, fmt.Errorf("error read chunk: %w", err)
+	}
+
+	var hSamples []histogramSample
+	it := c.Iterator(nil)
+	for {
+		typ := it.Next()
+		if typ == chunkenc.ValNone {
+			break
+		}
+		switch typ {
+		case chunkenc.ValHistogram:
+			ts, h := it.AtHistogram(nil)
+			hSamples = append(hSamples, histogramSample{
+				timestamp: ts,
+				fh:        h.ToFloat(nil),
+			})
+		case chunkenc.ValFloatHistogram:
+			ts, fh := it.AtFloatHistogram(nil)
+			hSamples = append(hSamples, histogramSample{
+				timestamp: ts,
+				fh:        fh,
+			})
+		default:
+			// Skip unsupported values
+			continue
+		}
+	}
+	if err := it.Err(); err != nil {
+		return nil, fmt.Errorf("error iterate over chunks: %w", err)
+	}
+
+	return hSamples, nil
+}
+
+// convertHistograms converts native histogram samples into VictoriaMetrics histogram
+// time series in the same way as VictoriaMetrics converts native histograms
+// received via Prometheus remote write protocol: every native histogram sample
+// is converted into `<name>_count` and `<name>_sum` series plus a set of
+// `<name>_bucket` series with `vmrange` labels containing non-cumulative bucket counts.
+// The only difference is that for native histograms with custom buckets (NHCB)
+// bucket bounds are taken from the custom values, while the remote write protocol
+// parser ignores custom values and estimates the bounds with the exponential formula.
+// See https://prometheus.io/docs/specs/native_histograms/#data-model
+func convertHistograms(hSamples []histogramSample, labels []prompb.Label) []*vm.TimeSeries {
+	if len(hSamples) == 0 {
+		return nil
+	}
+
+	labelPairs := make([]vm.LabelPair, 0, len(labels))
+	nameValue := ""
+	for _, label := range labels {
+		if label.Name == "__name__" {
+			nameValue = label.Value
+			continue
+		}
+		labelPairs = append(labelPairs, vm.LabelPair{Name: label.Name, Value: label.Value})
+	}
+	// the metric has no name, skip it in the same way as VictoriaMetrics does
+	// when it receives a native histogram without the metric name via remote write protocol.
+	if nameValue == "" {
+		return nil
+	}
+
+	countSeries := &vm.TimeSeries{
+		Name:       nameValue + "_count",
+		LabelPairs: labelPairs,
+	}
+	sumSeries := &vm.TimeSeries{
+		Name:       nameValue + "_sum",
+		LabelPairs: labelPairs,
+	}
+	bucketSeries := make(map[string]*vm.TimeSeries)
+	// vmranges preserves the order of bucketSeries creation
+	// in order to get deterministic results.
+	var vmranges []string
+
+	for _, hs := range hSamples {
+		fh := hs.fh
+		countSeries.Timestamps = append(countSeries.Timestamps, hs.timestamp)
+		countSeries.Values = append(countSeries.Values, fh.Count)
+		sumSeries.Timestamps = append(sumSeries.Timestamps, hs.timestamp)
+		sumSeries.Values = append(sumSeries.Values, fh.Sum)
+
+		it := fh.AllBucketIterator()
+		for it.Next() {
+			b := it.At()
+			if b.Count <= 0 {
+				continue
+			}
+			vmrange := formatVmrange(b.Lower, b.Upper)
+			s := bucketSeries[vmrange]
+			if s == nil {
+				bucketLabelPairs := make([]vm.LabelPair, len(labelPairs), len(labelPairs)+1)
+				copy(bucketLabelPairs, labelPairs)
+				bucketLabelPairs = append(bucketLabelPairs, vm.LabelPair{Name: "vmrange", Value: vmrange})
+				s = &vm.TimeSeries{
+					Name:       nameValue + "_bucket",
+					LabelPairs: bucketLabelPairs,
+				}
+				bucketSeries[vmrange] = s
+				vmranges = append(vmranges, vmrange)
+			}
+			s.Timestamps = append(s.Timestamps, hs.timestamp)
+			s.Values = append(s.Values, b.Count)
+		}
+	}
+
+	tss := make([]*vm.TimeSeries, 0, 2+len(vmranges))
+	tss = append(tss, countSeries, sumSeries)
+	for _, vmrange := range vmranges {
+		tss = append(tss, bucketSeries[vmrange])
+	}
+	return tss
+}
+
+// formatVmrange formats the given bucket bounds into `vmrange` label value
+// in the same way as VictoriaMetrics does for native histograms
+// received via Prometheus remote write protocol.
+func formatVmrange(lower, upper float64) string {
+	b := make([]byte, 0, 24)
+	b = strconv.AppendFloat(b, lower, 'e', 3, 64)
+	b = append(b, "..."...)
+	b = strconv.AppendFloat(b, upper, 'e', 3, 64)
+	return string(b)
+}
+
 type keyValue struct {
 	key   string
 	value string

app/vmctl/remoteread/remoteread_test.go

@@ -0,0 +1,334 @@
+package remoteread
+
+import (
+	"bytes"
+	"io"
+	"reflect"
+	"testing"
+
+	"github.com/gogo/protobuf/proto"
+	"github.com/golang/snappy"
+	"github.com/prometheus/prometheus/model/histogram"
+	"github.com/prometheus/prometheus/prompb"
+	"github.com/prometheus/prometheus/storage/remote"
+	"github.com/prometheus/prometheus/tsdb/chunkenc"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmctl/vm"
+)
+
+func testHistogram(mul int64) *histogram.Histogram {
+	return &histogram.Histogram{
+		Schema:          0,
+		Count:           uint64(10 * mul),
+		Sum:             25.5 * float64(mul),
+		ZeroThreshold:   0.001,
+		ZeroCount:       uint64(2 * mul),
+		PositiveSpans:   []histogram.Span{{Offset: 0, Length: 2}},
+		PositiveBuckets: []int64{1 * mul, 2 * mul},
+		NegativeSpans:   []histogram.Span{{Offset: 0, Length: 1}},
+		NegativeBuckets: []int64{4 * mul},
+	}
+}
+
+func TestConvertHistograms(t *testing.T) {
+	f := func(hSamples []histogramSample, labels []prompb.Label, expected []*vm.TimeSeries) {
+		t.Helper()
+
+		tss := convertHistograms(hSamples, labels)
+		if !reflect.DeepEqual(tss, expected) {
+			t.Fatalf("unexpected result\ngot:\n%v\nwant:\n%v", tss, expected)
+		}
+	}
+
+	// series without samples
+	f(nil, []prompb.Label{{Name: "__name__", Value: "foo"}}, nil)
+
+	// series without the metric name must be skipped
+	f([]histogramSample{
+		{timestamp: 1000, fh: testHistogram(1).ToFloat(nil)},
+	}, []prompb.Label{{Name: "job", Value: "bar"}}, nil)
+
+	// native histogram must be converted to _count, _sum and _bucket series
+	// in the same way as VictoriaMetrics does for Prometheus remote write protocol
+	labels := []prompb.Label{
+		{Name: "__name__", Value: "request_duration_seconds"},
+		{Name: "job", Value: "bar"},
+	}
+	jobLabel := []vm.LabelPair{{Name: "job", Value: "bar"}}
+	bucketLabels := func(vmrange string) []vm.LabelPair {
+		return []vm.LabelPair{
+			{Name: "job", Value: "bar"},
+			{Name: "vmrange", Value: vmrange},
+		}
+	}
+	f([]histogramSample{
+		{timestamp: 1000, fh: testHistogram(1).ToFloat(nil)},
+		{timestamp: 2000, fh: testHistogram(2).ToFloat(nil)},
+	}, labels, []*vm.TimeSeries{
+		{
+			Name:       "request_duration_seconds_count",
+			LabelPairs: jobLabel,
+			Timestamps: []int64{1000, 2000},
+			Values:     []float64{10, 20},
+		},
+		{
+			Name:       "request_duration_seconds_sum",
+			LabelPairs: jobLabel,
+			Timestamps: []int64{1000, 2000},
+			Values:     []float64{25.5, 51},
+		},
+		{
+			Name:       "request_duration_seconds_bucket",
+			LabelPairs: bucketLabels("-1.000e+00...-5.000e-01"),
+			Timestamps: []int64{1000, 2000},
+			Values:     []float64{4, 8},
+		},
+		{
+			Name:       "request_duration_seconds_bucket",
+			LabelPairs: bucketLabels("-1.000e-03...1.000e-03"),
+			Timestamps: []int64{1000, 2000},
+			Values:     []float64{2, 4},
+		},
+		{
+			Name:       "request_duration_seconds_bucket",
+			LabelPairs: bucketLabels("5.000e-01...1.000e+00"),
+			Timestamps: []int64{1000, 2000},
+			Values:     []float64{1, 2},
+		},
+		{
+			Name:       "request_duration_seconds_bucket",
+			LabelPairs: bucketLabels("1.000e+00...2.000e+00"),
+			Timestamps: []int64{1000, 2000},
+			Values:     []float64{3, 6},
+		},
+	})
+}
+
+func TestParseHistograms(t *testing.T) {
+	c := chunkenc.NewHistogramChunk()
+	app, err := c.Appender()
+	if err != nil {
+		t.Fatalf("cannot create chunk appender: %s", err)
+	}
+	if _, _, _, err := app.AppendHistogram(nil, 0, 1000, testHistogram(1), true); err != nil {
+		t.Fatalf("cannot append histogram: %s", err)
+	}
+	if _, _, _, err := app.AppendHistogram(nil, 0, 2000, testHistogram(2), true); err != nil {
+		t.Fatalf("cannot append histogram: %s", err)
+	}
+
+	hSamples, err := parseHistograms(prompb.Chunk_HISTOGRAM, c.Bytes())
+	if err != nil {
+		t.Fatalf("cannot parse histogram chunk: %s", err)
+	}
+	if len(hSamples) != 2 {
+		t.Fatalf("unexpected number of histogram samples; got %d; want 2", len(hSamples))
+	}
+	for i, expected := range []struct {
+		timestamp int64
+		count     float64
+		sum       float64
+	}{
+		{timestamp: 1000, count: 10, sum: 25.5},
+		{timestamp: 2000, count: 20, sum: 51},
+	} {
+		if hSamples[i].timestamp != expected.timestamp {
+			t.Fatalf("unexpected timestamp; got %d; want %d", hSamples[i].timestamp, expected.timestamp)
+		}
+		if hSamples[i].fh.Count != expected.count {
+			t.Fatalf("unexpected count; got %f; want %f", hSamples[i].fh.Count, expected.count)
+		}
+		if hSamples[i].fh.Sum != expected.sum {
+			t.Fatalf("unexpected sum; got %f; want %f", hSamples[i].fh.Sum, expected.sum)
+		}
+	}
+
+	// unsupported chunk encoding must return error
+	if _, err := parseHistograms(prompb.Chunk_XOR, c.Bytes()); err == nil {
+		t.Fatalf("expecting non-nil error for unsupported chunk encoding")
+	}
+}
+
+func TestProcessResponse(t *testing.T) {
+	readResp := &prompb.ReadResponse{
+		Results: []*prompb.QueryResult{
+			{
+				Timeseries: []*prompb.TimeSeries{
+					{
+						Labels: []prompb.Label{
+							{Name: "__name__", Value: "cpu_usage"},
+							{Name: "job", Value: "bar"},
+						},
+						Samples: []prompb.Sample{
+							{Timestamp: 1000, Value: 1.5},
+						},
+					},
+					{
+						Labels: []prompb.Label{
+							{Name: "__name__", Value: "request_duration_seconds"},
+							{Name: "job", Value: "bar"},
+						},
+						Histograms: []prompb.Histogram{
+							prompb.FromIntHistogram(1000, testHistogram(1)),
+						},
+					},
+				},
+			},
+		},
+	}
+	data, err := proto.Marshal(readResp)
+	if err != nil {
+		t.Fatalf("cannot marshal ReadResponse: %s", err)
+	}
+	compressed := snappy.Encode(nil, data)
+
+	var tss []*vm.TimeSeries
+	err = processResponse(io.NopCloser(bytes.NewReader(compressed)), func(ts *vm.TimeSeries) error {
+		tss = append(tss, ts)
+		return nil
+	})
+	if err != nil {
+		t.Fatalf("cannot process response: %s", err)
+	}
+
+	// 1 float series + _count + _sum + 4 buckets
+	if len(tss) != 7 {
+		t.Fatalf("unexpected number of time series; got %d; want 7", len(tss))
+	}
+	if tss[0].Name != "cpu_usage" || !reflect.DeepEqual(tss[0].Values, []float64{1.5}) {
+		t.Fatalf("unexpected float series: %v", tss[0])
+	}
+	if tss[1].Name != "request_duration_seconds_count" || !reflect.DeepEqual(tss[1].Values, []float64{10}) {
+		t.Fatalf("unexpected _count series: %v", tss[1])
+	}
+	if tss[2].Name != "request_duration_seconds_sum" || !reflect.DeepEqual(tss[2].Values, []float64{25.5}) {
+		t.Fatalf("unexpected _sum series: %v", tss[2])
+	}
+	for _, ts := range tss[3:] {
+		if ts.Name != "request_duration_seconds_bucket" {
+			t.Fatalf("unexpected bucket series name %q", ts.Name)
+		}
+	}
+}
+
+type nopFlusher struct{}
+
+func (nopFlusher) Flush() {}
+
+func TestProcessStreamResponse(t *testing.T) {
+	// build a histogram chunk
+	hc := chunkenc.NewHistogramChunk()
+	hApp, err := hc.Appender()
+	if err != nil {
+		t.Fatalf("cannot create histogram chunk appender: %s", err)
+	}
+	if _, _, _, err := hApp.AppendHistogram(nil, 0, 1000, testHistogram(1), true); err != nil {
+		t.Fatalf("cannot append histogram: %s", err)
+	}
+
+	// build a float chunk
+	xc := chunkenc.NewXORChunk()
+	xApp, err := xc.Appender()
+	if err != nil {
+		t.Fatalf("cannot create xor chunk appender: %s", err)
+	}
+	xApp.Append(0, 1000, 1.5)
+
+	res := &prompb.ChunkedReadResponse{
+		ChunkedSeries: []*prompb.ChunkedSeries{
+			{
+				Labels: []prompb.Label{
+					{Name: "__name__", Value: "request_duration_seconds"},
+					{Name: "job", Value: "bar"},
+				},
+				Chunks: []prompb.Chunk{
+					{Type: prompb.Chunk_HISTOGRAM, Data: hc.Bytes()},
+				},
+			},
+			{
+				Labels: []prompb.Label{
+					{Name: "__name__", Value: "cpu_usage"},
+				},
+				Chunks: []prompb.Chunk{
+					{Type: prompb.Chunk_XOR, Data: xc.Bytes()},
+				},
+			},
+			{
+				Labels: []prompb.Label{
+					{Name: "__name__", Value: "memory_usage"},
+				},
+				Chunks: []prompb.Chunk{
+					// the `type` field may be unset for XOR chunks,
+					// such chunks must be parsed as XOR ones
+					{Type: prompb.Chunk_UNKNOWN, Data: xc.Bytes()},
+				},
+			},
+		},
+	}
+	data, err := proto.Marshal(res)
+	if err != nil {
+		t.Fatalf("cannot marshal ChunkedReadResponse: %s", err)
+	}
+	var buf bytes.Buffer
+	cw := remote.NewChunkedWriter(&buf, nopFlusher{})
+	if _, err := cw.Write(data); err != nil {
+		t.Fatalf("cannot write chunked response: %s", err)
+	}
+
+	var tss []*vm.TimeSeries
+	err = processStreamResponse(io.NopCloser(&buf), func(ts *vm.TimeSeries) error {
+		tss = append(tss, ts)
+		return nil
+	})
+	if err != nil {
+		t.Fatalf("cannot process stream response: %s", err)
+	}
+
+	// _count + _sum + 4 buckets + 1 float series + 1 float series from UNKNOWN chunk
+	if len(tss) != 8 {
+		t.Fatalf("unexpected number of time series; got %d; want 8", len(tss))
+	}
+	if tss[0].Name != "request_duration_seconds_count" || !reflect.DeepEqual(tss[0].Values, []float64{10}) {
+		t.Fatalf("unexpected _count series: %v", tss[0])
+	}
+	if tss[1].Name != "request_duration_seconds_sum" || !reflect.DeepEqual(tss[1].Values, []float64{25.5}) {
+		t.Fatalf("unexpected _sum series: %v", tss[1])
+	}
+	for _, ts := range tss[2:6] {
+		if ts.Name != "request_duration_seconds_bucket" {
+			t.Fatalf("unexpected bucket series name %q", ts.Name)
+		}
+	}
+	if tss[6].Name != "cpu_usage" || !reflect.DeepEqual(tss[6].Values, []float64{1.5}) {
+		t.Fatalf("unexpected float series: %v", tss[6])
+	}
+	if tss[7].Name != "memory_usage" || !reflect.DeepEqual(tss[7].Values, []float64{1.5}) {
+		t.Fatalf("unexpected float series from UNKNOWN chunk: %v", tss[7])
+	}
+}
+
+func TestParseFloatHistograms(t *testing.T) {
+	c := chunkenc.NewFloatHistogramChunk()
+	app, err := c.Appender()
+	if err != nil {
+		t.Fatalf("cannot create chunk appender: %s", err)
+	}
+	fh := testHistogram(1).ToFloat(nil)
+	if _, _, _, err := app.AppendFloatHistogram(nil, 0, 1000, fh, true); err != nil {
+		t.Fatalf("cannot append float histogram: %s", err)
+	}
+
+	hSamples, err := parseHistograms(prompb.Chunk_FLOAT_HISTOGRAM, c.Bytes())
+	if err != nil {
+		t.Fatalf("cannot parse float histogram chunk: %s", err)
+	}
+	if len(hSamples) != 1 {
+		t.Fatalf("unexpected number of histogram samples; got %d; want 1", len(hSamples))
+	}
+	if hSamples[0].timestamp != 1000 {
+		t.Fatalf("unexpected timestamp; got %d; want 1000", hSamples[0].timestamp)
+	}
+	if hSamples[0].fh.Count != 10 {
+		t.Fatalf("unexpected count; got %f; want 10", hSamples[0].fh.Count)
+	}
+}

apptest/tests/prometheus_mock_storage.go

@@ -59,7 +59,7 @@ func (ms *PrometheusMockStorage) Read(_ context.Context, query *prompb.Query, so
 		}
 
 		if !notMatch {
-			q.Timeseries = append(q.Timeseries, &prompb.TimeSeries{Labels: s.Labels, Samples: s.Samples})
+			q.Timeseries = append(q.Timeseries, &prompb.TimeSeries{Labels: s.Labels, Samples: s.Samples, Histograms: s.Histograms})
 		}
 	}
 

apptest/tests/remote_read_server.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/gogo/protobuf/proto"
 	"github.com/golang/snappy"
+	"github.com/prometheus/prometheus/model/histogram"
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/prompb"
 	"github.com/prometheus/prometheus/storage/remote"
@@ -86,10 +87,17 @@ func (rrs *RemoteReadServer) getReadHandler(t *testing.T) http.Handler {
 						samples = append(samples, sample)
 					}
 				}
+				var histograms []prompb.Histogram
+				for _, h := range s.Histograms {
+					if h.Timestamp >= startTs && h.Timestamp < endTs {
+						histograms = append(histograms, h)
+					}
+				}
 				var series prompb.TimeSeries
-				if len(samples) > 0 {
+				if len(samples) > 0 || len(histograms) > 0 {
 					series.Labels = s.Labels
 					series.Samples = samples
+					series.Histograms = histograms
 				}
 				ts[i] = &series
 			}
@@ -317,6 +325,37 @@ func generateRemoteReadSamples(idx int, startTime, endTime, numOfSamples int64)
 	return samples
 }
 
+// GenerateRemoteReadHistogramSeries generates a remote read series
+// with native histogram samples within the given time range.
+func GenerateRemoteReadHistogramSeries(start, end, numOfSamples int64) []*prompb.TimeSeries {
+	timeSeries := &prompb.TimeSeries{
+		Labels: []prompb.Label{
+			{Name: labels.MetricName, Value: "vm_histogram_metric"},
+			{Name: "job", Value: "0"},
+		},
+	}
+
+	delta := (end - start) / numOfSamples
+	mul := int64(0)
+	for t := start; t != end; t += delta {
+		mul++
+		h := &histogram.Histogram{
+			Schema:          0,
+			Count:           uint64(10 * mul),
+			Sum:             25.5 * float64(mul),
+			ZeroThreshold:   0.001,
+			ZeroCount:       uint64(2 * mul),
+			PositiveSpans:   []histogram.Span{{Offset: 0, Length: 2}},
+			PositiveBuckets: []int64{mul, 2 * mul},
+			NegativeSpans:   []histogram.Span{{Offset: 0, Length: 1}},
+			NegativeBuckets: []int64{4 * mul},
+		}
+		timeSeries.Histograms = append(timeSeries.Histograms, prompb.FromIntHistogram(t*1000, h))
+	}
+
+	return []*prompb.TimeSeries{timeSeries}
+}
+
 func labelsToLabelsProto(ls labels.Labels) []prompb.Label {
 	result := make([]prompb.Label, 0, ls.Len())
 	ls.Range(func(l labels.Label) {

apptest/tests/vmctl_remote_read_mogration_test.go

@@ -75,6 +75,118 @@ func TestClusterVmctlRemoteReadProtocol(t *testing.T) {
 	testRemoteReadProtocol(tc, clusterDst, newRemoteReadServer, vmctlFlags)
 }
 
+func TestSingleVmctlRemoteReadNativeHistograms(t *testing.T) {
+	fs.MustRemoveDir(t.Name())
+
+	tc := apptest.NewTestCase(t)
+	defer tc.Stop()
+
+	vmsingleDst := tc.MustStartDefaultVmsingle()
+	vmAddr := fmt.Sprintf("http://%s/", vmsingleDst.HTTPAddr())
+	vmctlFlags := []string{
+		`remote-read`,
+		`--remote-read-filter-time-start=2025-06-11T15:31:10Z`,
+		`--remote-read-filter-time-end=2025-06-11T15:31:20Z`,
+		`--remote-read-step-interval=minute`,
+		`--vm-addr=` + vmAddr,
+		`--disable-progress-bar=true`,
+	}
+
+	testRemoteReadNativeHistograms(tc, vmsingleDst, NewRemoteReadServer, vmctlFlags)
+}
+
+func TestSingleVmctlRemoteReadStreamNativeHistograms(t *testing.T) {
+	fs.MustRemoveDir(t.Name())
+
+	tc := apptest.NewTestCase(t)
+	defer tc.Stop()
+
+	vmsingleDst := tc.MustStartDefaultVmsingle()
+	vmAddr := fmt.Sprintf("http://%s/", vmsingleDst.HTTPAddr())
+	vmctlFlags := []string{
+		`remote-read`,
+		`--remote-read-filter-time-start=2025-06-11T15:31:10Z`,
+		`--remote-read-filter-time-end=2025-06-11T15:31:20Z`,
+		`--remote-read-step-interval=minute`,
+		`--vm-addr=` + vmAddr,
+		`--remote-read-use-stream=true`,
+		`--disable-progress-bar=true`,
+	}
+
+	testRemoteReadNativeHistograms(tc, vmsingleDst, NewRemoteReadStreamServer, vmctlFlags)
+}
+
+// testRemoteReadNativeHistograms verifies that native histograms are migrated
+// as _count, _sum and _bucket series with vmrange labels in the same way
+// as VictoriaMetrics converts native histograms received via Prometheus remote write protocol.
+func testRemoteReadNativeHistograms(tc *apptest.TestCase, sut apptest.PrometheusWriteQuerier, newRemoteReadServer func(t *testing.T, series []*prompb.TimeSeries) *RemoteReadServer, vmctlFlags []string) {
+	t := tc.T()
+	t.Helper()
+
+	series := GenerateRemoteReadHistogramSeries(1749655870, 1749655880, 2)
+
+	rrs := newRemoteReadServer(t, series)
+	defer rrs.Close()
+
+	vmctlFlags = append(vmctlFlags, `--remote-read-src-addr=`+rrs.HTTPAddr())
+	tc.MustStartVmctl("vmctl", vmctlFlags)
+
+	sut.ForceFlush(t)
+
+	tc.Assert(&apptest.AssertOptions{
+		Retries: 300,
+		Msg:     `unexpected native histogram metrics stored on vmsingle via the prometheus protocol`,
+		Got: func() any {
+			got := sut.PrometheusAPIV1Export(t, `{__name__=~".*"}`, apptest.QueryOpts{
+				Start: "2025-06-11T15:31:10Z",
+				End:   "2025-06-11T15:32:20Z",
+			})
+			got.Sort()
+			return got.Data.Result
+		},
+		Want: expectedNativeHistogramQueryResult(),
+		CmpOpts: []cmp.Option{
+			cmpopts.IgnoreFields(apptest.PrometheusAPIV1QueryResponse{}, "Status", "Data.ResultType"),
+		},
+	})
+}
+
+// expectedNativeHistogramQueryResult returns the series expected to be stored in VictoriaMetrics
+// after migrating the series generated by GenerateRemoteReadHistogramSeries(1749655870, 1749655880, 2).
+func expectedNativeHistogramQueryResult() []*apptest.QueryResult {
+	metric := func(name, vmrange string) map[string]string {
+		m := map[string]string{
+			"__name__": name,
+			"job":      "0",
+		}
+		if vmrange != "" {
+			m["vmrange"] = vmrange
+		}
+		return m
+	}
+	samples := func(v1, v2 float64) []*apptest.Sample {
+		return []*apptest.Sample{
+			{Timestamp: 1749655870000, Value: v1},
+			{Timestamp: 1749655875000, Value: v2},
+		}
+	}
+	resp := &apptest.PrometheusAPIV1QueryResponse{
+		Data: &apptest.QueryData{
+			Result: []*apptest.QueryResult{
+				{Metric: metric("vm_histogram_metric_count", ""), Samples: samples(10, 20)},
+				{Metric: metric("vm_histogram_metric_sum", ""), Samples: samples(25.5, 51)},
+				{Metric: metric("vm_histogram_metric_bucket", "-1.000e+00...-5.000e-01"), Samples: samples(4, 8)},
+				{Metric: metric("vm_histogram_metric_bucket", "-1.000e-03...1.000e-03"), Samples: samples(2, 4)},
+				{Metric: metric("vm_histogram_metric_bucket", "5.000e-01...1.000e+00"), Samples: samples(1, 2)},
+				{Metric: metric("vm_histogram_metric_bucket", "1.000e+00...2.000e+00"), Samples: samples(3, 6)},
+			},
+		},
+	}
+	// sort in the same way as the exported result
+	resp.Sort()
+	return resp.Data.Result
+}
+
 func testRemoteReadProtocol(tc *apptest.TestCase, sut apptest.PrometheusWriteQuerier, newRemoteReadServer func(t *testing.T) *RemoteReadServer, vmctlFlags []string) {
 	t := tc.T()
 	t.Helper()

docs/victoriametrics/changelog/CHANGELOG.md

@@ -32,14 +32,19 @@ See also [LTS releases](https://docs.victoriametrics.com/victoriametrics/lts-rel
 
 * SECURITY: [vmsingle](https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/) and `vmselect` in [VictoriaMetrics cluster](https://docs.victoriametrics.com/victoriametrics/cluster-victoriametrics/): restrict `/api/v1/admin/tsdb/delete_series`, `/tags/delSeries` endpoints to `POST` method only to prevent some [SSRF](https://en.wikipedia.org/wiki/Server-side_request_forgery)-based data deletion attacks. See [#5552](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5552).
 
+* FEATURE: [dashboards](https://github.com/VictoriaMetrics/VictoriaMetrics/tree/master/dashboards): add `Fsync avg duration` panel to the Troubleshooting section of the single-node, cluster, and vmagent dashboards. This panel surfaces degradation of IO operation for faster incident triage. See [#10432](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10432).
 * FEATURE: [vmagent](https://docs.victoriametrics.com/victoriametrics/vmagent/): add `name` label identifying the corresponding `-remoteWrite.url` target to the `vm_persistentqueue_*` metrics exposed by persistent queue. See [#7944](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/7944). Thanks to @tIGO for contribution.
+* FEATURE: [vmagent](https://docs.victoriametrics.com/victoriametrics/vmagent/): add `-remoteWrite.obfuscateLabels` flag for hashing values of the specified labels before sending metrics to the corresponding `-remoteWrite.url`. This allows sharing metrics with external systems while keeping sensitive label values hidden. See [#10599](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10599).
+* FEATURE: [vmalert](https://docs.victoriametrics.com/victoriametrics/vmalert/): add `-replay.continueWithExecutionErr` flag to allow continuing to replay other rules when a rule execution fails with a 422 response code, which can happen due to an expression syntax error or a resource limit being hit. See [11313](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11313).
+* FEATURE: [vmalert](https://docs.victoriametrics.com/victoriametrics/vmalert/): add template variable `$interval` to expose the alerting rule group's evaluation interval. This allows generating dashboard links with a lookback window relative to the rule's interval, for example `&from={{ ($activeAt.Add (parseDurationTime (printf "-%s" .Interval))).UnixMilli }}&to={{ $activeAt.UnixMilli }}`. See this issue [#11232](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11232) for more details. Thanks to @1solomonwakhungu for contribution.
+* FEATURE: [vmbackupmanager](https://docs.victoriametrics.com/victoriametrics/vmbackupmanager/) and [alerts](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/deployment/docker/rules): introduce `vm_backup_last_success_at` metric to track the last successful backup by type. Add [alerting rules](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/deployment/docker/rules/alerts-vmbackupmanager.yml) `NoLatestBackupWithinLastDay`, `NoHourlyBackupWithinLastDay`, 
+`NoDailyBackupWithinLast3Days`, `NoWeeklyBackupWithinLast14Days` and `NoMonthlyBackupWithinLast62Days` to remind users about the missing backups. See [#11217](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11217).
+* FEATURE: [vmctl](https://docs.victoriametrics.com/victoriametrics/vmctl/): support [Prometheus native histograms](https://prometheus.io/docs/specs/native_histograms/) migration in [remote read mode](https://docs.victoriametrics.com/victoriametrics/vmctl/remoteread/). Native histograms are converted into `_count`, `_sum` and `_bucket` series with `vmrange` labels in the same way as VictoriaMetrics converts native histograms received via Prometheus remote write protocol, except that for native histograms with custom buckets the original bucket bounds are preserved instead of being estimated with the exponential formula. Previously native histograms were silently ignored in `SAMPLES` mode, while in stream mode the migration failed with `EOF` error. See [#11292](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11292). Thanks to @liuxu623 for contribution.
 * FEATURE: `vminsert` in [VictoriaMetrics cluster](https://docs.victoriametrics.com/victoriametrics/cluster-victoriametrics/): enable [slowness-based re-routing](https://docs.victoriametrics.com/victoriametrics/cluster-victoriametrics/#slowness-based-re-routing) by default. Previously, `-disableRerouting` defaulted to `true`, which limited ingestion throughput to the slowest `vmstorage` node. Now `-disableRerouting` defaults to `false`, so `vminsert` automatically routes data away from the slowest `vmstorage` node, improving overall ingestion performance. Slowness re-routing is automatically disabled when `-replicationFactor` is greater than 1. See [#11287](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/11287).
 * FEATURE: [vmui](https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/#vmui): persist the selected auto-refresh interval in the URL. See [VictoriaLogs#1310](https://github.com/VictoriaMetrics/VictoriaLogs/issues/1310).
-* FEATURE: [dashboards](https://github.com/VictoriaMetrics/VictoriaMetrics/tree/master/dashboards): add `Fsync avg duration` panel to the Troubleshooting section of the single-node, cluster, and vmagent dashboards. This panel surfaces degradation of IO operation for faster incident triage. See [#10432](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10432).
-* FEATURE: [vmbackupmanager](https://docs.victoriametrics.com/victoriametrics/vmbackupmanager/) and [alerts](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/deployment/docker/rules): introduce `vm_backup_last_success_at` metric to track the last successful backup by type. Add [alerting rules](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/deployment/docker/rules/alerts-vmbackupmanager.yml) `NoLatestBackupWithinLastDay`, `NoHourlyBackupWithinLastDay`, `NoDailyBackupWithinLast3Days`, `NoWeeklyBackupWithinLast14Days` and `NoMonthlyBackupWithinLast62Days` to remind users about the missing backups. See [#11217](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11217).
-* FEATURE: [vmagent](https://docs.victoriametrics.com/victoriametrics/vmagent/): add `-remoteWrite.obfuscateLabels` flag for hashing values of the specified labels before sending metrics to the corresponding `-remoteWrite.url`. This allows sharing metrics with external systems while keeping sensitive label values hidden. See [#10599](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10599).
 
 * BUGFIX: [MetricsQL](https://docs.victoriametrics.com/victoriametrics/metricsql/): properly drop data points filtered out by an inner [comparison operation](https://prometheus.io/docs/prometheus/latest/querying/operators/#comparison-binary-operators) when its result is used on the right side of another comparison. Previously, queries like `foo != (bar > 100)` could return unexpected results because filtered-out data points are represented internally as `NaN`, and `value != NaN` evaluates to `true`. Comparisons against explicitly present `NaN` values keep the previous behavior. See [#10018](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10018). Thanks to @zasdaym for contribution.
+* BUGFIX: [vmagent](https://docs.victoriametrics.com/victoriametrics/vmagent/) and [vmsingle](https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/): ignore HTTP proxy environment variables when scraping targets over Unix domain sockets. See [#11318](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/11318). Thanks to @lwmacct for contribution.
 * BUGFIX: [vmalert](https://docs.victoriametrics.com/victoriametrics/vmalert/): fixed the display of rule state badges on the `Groups` page in the web UI. See [#11160](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11160).
 * BUGFIX: [vmbackupmanager](https://docs.victoriametrics.com/victoriametrics/vmbackupmanager/): previously, `vmbackupmanager` was crashing on startup when it failed to restore backup state from remote storage, causing a crash loop. Now it logs the error and continues running, retrying the state restore before each scheduled backup. Added `vm_backup_errors_total{type="restoreState"}` metric to track backup state restore failures. See [#11217](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/11217).
 

docs/victoriametrics/vmalert.md

@@ -341,6 +341,7 @@ The following variables are available in templating:
 | $externalLabels or .ExternalLabels | List of labels configured via `-external.label` command-line flag.                                                                                    | `Issues with {{ $labels.instance }} (datacenter-{{ $externalLabels.dc }})`                                                                                                             |
 | $externalURL or .ExternalURL       | URL configured via `-external.url` command-line flag. Used for cases when vmalert is hidden behind proxy.                                             | `Visit {{ $externalURL }} for more details`                                                                                                                                            |
 | $isPartial or .IsPartial           | Indicates whether the latest rule query response from the datasource(that supports returning `isPartial` option, such as vmcluster) could be partial. | `{{ if $isPartial }}WARNING: The latest alert state may be a false alarm due to a partial response from the datasource.{{ end }}`                                                      |
+| $interval or .Interval             | Alerting rule group's evaluation interval.                                                                                                            | `http://vm-grafana.com/<dashboard-id>?viewPanel=<panel-id>&from={{ ($activeAt.Add (parseDurationTime (printf "-%s" .Interval))).UnixMilli }}&to={{ $activeAt.UnixMilli }}` |
 
 Additionally, `vmalert` provides some extra templating functions listed in [template functions](#template-functions) and [reusable templates](#reusable-templates).
 

docs/victoriametrics/vmalert_common_flags.md

@@ -404,6 +404,8 @@ See the docs at https://docs.victoriametrics.com/victoriametrics/vmalert/ .
      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 persist alerts state and recording rules results in form of timeseries. It must support either VictoriaMetrics remote write protocol or Prometheus remote_write protocol. Supports address in the form of IP address with a port (e.g., http://127.0.0.1:8428) or DNS SRV record. For example, if -remoteWrite.url=http://127.0.0.1:8428 is specified, then the alerts state will be written to http://127.0.0.1:8428/api/v1/write . See also -remoteWrite.disablePathAppend, '-remoteWrite.showURL'.
+  -replay.continueWithExecutionErr bool
+     Whether to continue replaying other rules if a rule execution fails with a 422 response code, which can happen due to an expression syntax error or a resource limit being hit.
   -replay.disableProgressBar
      Whether to disable rendering progress bars during the replay. Progress bar rendering might be verbose or break the logs parsing, so it is recommended to be disabled when not used in interactive mode.
   -replay.maxDatapointsPerQuery int
@@ -411,7 +413,7 @@ See the docs at https://docs.victoriametrics.com/victoriametrics/vmalert/ .
   -replay.ruleEvaluationConcurrency int
      The maximum number of concurrent '/query_range' requests when replay recording rule or alerting rule with for=0. Increasing this value when replaying for a long time, since each request is limited by -replay.maxDatapointsPerQuery. (default 1)
   -replay.ruleRetryAttempts int
-     Defines how many retries to make before giving up on rule if request for it returns an error. (default 5)
+     Defines how many retries to make before giving up on rule if request for it returns a retriable error. (default 5)
   -replay.rulesDelay duration
      Delay before evaluating the next rule within the group. Is important for chained rules. Keep it equal or bigger than -remoteWrite.flushInterval. When set to >0, replay ignores group's concurrency setting. (default 1s)
   -replay.timeFrom string

lib/promscrape/client.go

@@ -90,7 +90,11 @@ func newClient(ctx context.Context, sw *ScrapeWork) (*client, error) {
 	}
 
 	tr := httputil.NewTransport(false, "vm_promscrape")
-	if proxyURLFunc != nil {
+	if sw.UnixSocket != "" {
+		// Unix sockets are direct local endpoints and cannot be reached via HTTP proxies.
+		// Proxy could be set implicitly via global env variable HTTP_PROXY
+		tr.Proxy = nil
+	} else if proxyURLFunc != nil {
 		tr.Proxy = proxyURLFunc
 	}
 	tr.TLSHandshakeTimeout = 10 * time.Second