app/vmagent/remotewrite: follow-up for 166b97b and b6bd9a9

- Make the configuration more clear by accepting the list of ignored labels during sharding
  via a dedicated command-line flag - -remoteWrite.shardByURL.ignoreLabels.
  This prevents from overloading the meaning of -remoteWrite.shardByURL.labels command-line flag.

- Removed superfluous memory allocation per each processed sample if sharding by remote storage is enabled.

Updates #5938

app/vmagent/remotewrite/remotewrite.go

@@ -51,9 +51,11 @@ var (
 		"By default the data is replicated across all the -remoteWrite.url . See https://docs.victoriametrics.com/vmagent.html#sharding-among-remote-storages")
 	shardByURLLabels = flagutil.NewArrayString("remoteWrite.shardByURL.labels", "Optional list of labels, which must be used for sharding outgoing samples "+
 		"among remote storage systems if -remoteWrite.shardByURL command-line flag is set. By default all the labels are used for sharding in order to gain "+
-		"even distribution of series over the specified -remoteWrite.url systems. See also -remoteWrite.shardByURL.inverseLabels.")
-	shardByURLLabelsInverse = flag.Bool("remoteWrite.shardByURL.inverseLabels", false, "Inverse the behavior of -remoteWrite.shardByURL.labels so that series are sharded using all labels except the ones specified in -remoteWrite.shardByURL.labels.")
-	tmpDataPath             = flag.String("remoteWrite.tmpDataPath", "vmagent-remotewrite-data", "Path to directory for storing pending data, which isn't sent to the configured -remoteWrite.url . "+
+		"even distribution of series over the specified -remoteWrite.url systems. See also -remoteWrite.shardByURL.ignoreLabels")
+	shardByURLIgnoreLabels = flagutil.NewArrayString("remoteWrite.shardByURL.ignoreLabels", "Optional list of labels, which must be ignored when sharding outgoing samples "+
+		"among remote storage systems if -remoteWrite.shardByURL command-line flag is set. By default all the labels are used for sharding in order to gain "+
+		"even distribution of series over the specified -remoteWrite.url systems. See also -remoteWrite.shardByURL.labels")
+	tmpDataPath = flag.String("remoteWrite.tmpDataPath", "vmagent-remotewrite-data", "Path to directory for storing pending data, which isn't sent to the configured -remoteWrite.url . "+
 		"See also -remoteWrite.maxDiskUsagePerURL and -remoteWrite.disableOnDiskQueue")
 	keepDanglingQueues = flag.Bool("remoteWrite.keepDanglingQueues", false, "Keep persistent queues contents at -remoteWrite.tmpDataPath in case there are no matching -remoteWrite.url. "+
 		"Useful when -remoteWrite.url is changed temporarily and persistent queue files will be needed later on.")
@@ -150,7 +152,10 @@ func InitSecretFlags() {
 	}
 }
 
-var shardByURLLabelsMap map[string]struct{}
+var (
+	shardByURLLabelsMap       map[string]struct{}
+	shardByURLIgnoreLabelsMap map[string]struct{}
+)
 
 // Init initializes remotewrite.
 //
@@ -189,13 +194,14 @@ func Init() {
 	if *queues <= 0 {
 		*queues = 1
 	}
-	if len(*shardByURLLabels) > 0 {
-		m := make(map[string]struct{}, len(*shardByURLLabels))
-		for _, label := range *shardByURLLabels {
-			m[label] = struct{}{}
-		}
-		shardByURLLabelsMap = m
+
+	if len(*shardByURLLabels) > 0 && len(*shardByURLIgnoreLabels) > 0 {
+		logger.Fatalf("-remoteWrite.shardByURL.labels and -remoteWrite.shardByURL.ignoreLabels cannot be set simultaneously; " +
+			"see https://docs.victoriametrics.com/vmagent/#sharding-among-remote-storages")
 	}
+	shardByURLLabelsMap = newMapFromStrings(*shardByURLLabels)
+	shardByURLIgnoreLabelsMap = newMapFromStrings(*shardByURLIgnoreLabels)
+
 	initLabelsGlobal()
 
 	// Register SIGHUP handler for config reload before loadRelabelConfigs.
@@ -561,7 +567,24 @@ func tryPushBlockToRemoteStorages(rwctxs []*remoteWriteCtx, tssBlock []prompbmar
 		tssByURL := make([][]prompbmarshal.TimeSeries, len(rwctxs))
 		tmpLabels := promutils.GetLabels()
 		for _, ts := range tssBlock {
-			hashLabels := extractShardingLabels(tmpLabels.Labels, ts.Labels, *shardByURLLabelsInverse)
+			hashLabels := ts.Labels
+			if len(shardByURLLabelsMap) > 0 {
+				hashLabels = tmpLabels.Labels[:0]
+				for _, label := range ts.Labels {
+					if _, ok := shardByURLLabelsMap[label.Name]; ok {
+						hashLabels = append(hashLabels, label)
+					}
+				}
+				tmpLabels.Labels = hashLabels
+			} else if len(shardByURLIgnoreLabelsMap) > 0 {
+				hashLabels = tmpLabels.Labels[:0]
+				for _, label := range ts.Labels {
+					if _, ok := shardByURLIgnoreLabelsMap[label.Name]; !ok {
+						hashLabels = append(hashLabels, label)
+					}
+				}
+				tmpLabels.Labels = hashLabels
+			}
 			h := getLabelsHash(hashLabels)
 			idx := h % uint64(len(tssByURL))
 			tssByURL[idx] = append(tssByURL[idx], ts)
@@ -607,20 +630,6 @@ func tryPushBlockToRemoteStorages(rwctxs []*remoteWriteCtx, tssBlock []prompbmar
 	return !anyPushFailed.Load()
 }
 
-func extractShardingLabels(dst, src []prompbmarshal.Label, inverse bool) []prompbmarshal.Label {
-	if len(shardByURLLabelsMap) < 1 {
-		return src
-	}
-	dst = dst[:0]
-	for _, label := range src {
-		_, ok := shardByURLLabelsMap[label.Name]
-		if ok && !inverse || !ok && inverse {
-			dst = append(dst, label)
-		}
-	}
-	return dst
-}
-
 // sortLabelsIfNeeded sorts labels if -sortLabels command-line flag is set.
 func sortLabelsIfNeeded(tss []prompbmarshal.TimeSeries) {
 	if !*sortLabels {
@@ -1022,3 +1031,11 @@ func CheckStreamAggrConfigs() error {
 	}
 	return nil
 }
+
+func newMapFromStrings(a []string) map[string]struct{} {
+	m := make(map[string]struct{}, len(a))
+	for _, s := range a {
+		m[s] = struct{}{}
+	}
+	return m
+}

docs/CHANGELOG.md

@@ -55,7 +55,7 @@ See also [LTS releases](https://docs.victoriametrics.com/lts-releases/).
 * FEATURE: [vmui](https://docs.victoriametrics.com/#vmui): improve trace display for better visual separation of branches. See [this pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5926).
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): ability to limit the ingestion rate via `-maxIngestionRate` command-line flag. See [this pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5900). 
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): use the provided `-remoteWrite.tlsServerName` as `Host` header in requests to `-remoteWrite.url`. This allows sending data to https remote storage by IP address instead of hostname. Thanks to @minor-fixes for initial idea and [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5802).
-* FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): add `-remoteWrite.shardByURL.inverseLabels` cmd-line flag to enhance sharding logic across configured `-remoteWrite.url` URLs when `-remoteWrite.shardByURL.labels` is set. Thanks to @edma2 for the idea and [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5938).
+* FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): add `-remoteWrite.shardByURL.ignoreLabels` command-line flag, which can be used for specifying the ignored list of labels when [sharding by `-remoteWrite.url` is enabled](https://docs.victoriametrics.com/vmagent/#sharding-among-remote-storages). Thanks to @edma2 for the idea and [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5938).
 * FEATURE: optimize [`/api/v1/labels`](https://docs.victoriametrics.com/url-examples/#apiv1labels) and [`/api/v1/label/.../values`](https://docs.victoriametrics.com/url-examples/#apiv1labelvalues) when `match[]` filters contains metric name. For example, `/api/v1/label/instance/values?match[]=up` now works much faster than before. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5055).
 * FEATURE: [vmctl](https://docs.victoriametrics.com/vmctl.html): support client-side TLS configuration for [native protocol](https://docs.victoriametrics.com/vmctl/#migrating-data-from-victoriametrics). See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5748). Thanks to @khushijain21 for the [pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5824).
 * FEATURE: [vmctl](https://docs.victoriametrics.com/vmctl.html): support client-side TLS configuration for VictoriaMetrics destination specified via `--vm-*` cmd-line flags used in [InfluxDB](https://docs.victoriametrics.com/vmctl/#migrating-data-from-influxdb-1x), [Remote Read protocol](https://docs.victoriametrics.com/vmctl/#migrating-data-by-remote-read-protocol), [OpenTSDB](https://docs.victoriametrics.com/vmctl/#migrating-data-from-opentsdb), [Prometheus](https://docs.victoriametrics.com/vmctl/#migrating-data-from-prometheus) and [Promscale](https://docs.victoriametrics.com/vmctl/#migrating-data-from-promscale) migration modes.

docs/vmagent.md

@@ -187,12 +187,17 @@ and [histogram](https://docs.victoriametrics.com/keyConcepts.html#histogram) typ
 to the same second-level `vmagent` instance, so they are aggregated properly.
 
 If `-remoteWrite.shardByURL` command-line flag is set, then all the metric labels are used for even sharding
-among remote storage systems specified in `-remoteWrite.url`. Sometimes it may be needed to use only a particular
-set of labels for sharding. For example, it may be needed to route all the metrics with the same `instance` label
+among remote storage systems specified in `-remoteWrite.url`.
+
+Sometimes it may be needed to use only a particular set of labels for sharding. For example, it may be needed to route all the metrics with the same `instance` label
 to the same `-remoteWrite.url`. In this case you can specify comma-separated list of these labels in the `-remoteWrite.shardByURL.labels`
 command-line flag. For example, `-remoteWrite.shardByURL.labels=instance,__name__` would shard metrics with the same name and `instance`
-label to the same `-remoteWrite.url`. The sharding logic can be inverted by specifying `-remoteWrite.shardByURL.inverseLabels`,
-so that metrics are sharded using all labels except the ones specified in `-remoteWrite.shardByURL.labels`.
+label to the same `-remoteWrite.url`.
+
+Sometimes is may be needed ignoring some labels when sharding samples across multiple `-remoteWrite.url` backends.
+For example, if all the [raw samples](https://docs.victoriametrics.com/keyconcepts/#raw-samples) with the same set of labels
+except of `instance` and `pod` labels must be routed to the same backend. In this case the list of ignored labels must be passed to
+`-remoteWrite.shardByURL.ignoreLabels` command-line flag: `-remoteWrite.shardByURL.ignoreLabels=instance,pod`.
 
 See also [how to scrape big number of targets](#scraping-big-number-of-targets).
 
@@ -2106,10 +2111,12 @@ See the docs at https://docs.victoriametrics.com/vmagent.html .
      Empty values are set to default value.
   -remoteWrite.shardByURL
      Whether to shard outgoing series across all the remote storage systems enumerated via -remoteWrite.url . By default the data is replicated across all the -remoteWrite.url . See https://docs.victoriametrics.com/vmagent.html#sharding-among-remote-storages
-  -remoteWrite.shardByURL.inverseLabels
-      Inverse the behavior of -remoteWrite.shardByURL.labels so that series are sharded using all labels except the ones specified in -remoteWrite.shardByURL.labels.
+  -remoteWrite.shardByURL.ignoreLabels array
+     Optional list of labels, which must be ignored when sharding outgoing samples among remote storage systems if -remoteWrite.shardByURL command-line flag is set. By default all the labels are used for sharding in order to gain even distribution of series over the specified -remoteWrite.url systems. See also -remoteWrite.shardByURL.labels
+     Supports an array of values separated by comma or specified via multiple flags.
+     Value can contain comma inside single-quoted or double-quoted string, {}, [] and () braces.
   -remoteWrite.shardByURL.labels array
-     Optional list of labels, which must be used for sharding outgoing samples among remote storage systems if -remoteWrite.shardByURL command-line flag is set. By default all the labels are used for sharding in order to gain even distribution of series over the specified -remoteWrite.url systems. See also -remoteWrite.shardByURL.inverseLabels.
+     Optional list of labels, which must be used for sharding outgoing samples among remote storage systems if -remoteWrite.shardByURL command-line flag is set. By default all the labels are used for sharding in order to gain even distribution of series over the specified -remoteWrite.url systems. See also -remoteWrite.shardByURL.ignoreLabels
      Supports an array of values separated by comma or specified via multiple flags.
      Value can contain comma inside single-quoted or double-quoted string, {}, [] and () braces.
   -remoteWrite.showURL