app/vminsert: add -maxLabelValueLen command-line flag

See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1908

README.md

@@ -1651,8 +1651,10 @@ Pass `-help` to VictoriaMetrics in order to see the list of supported command-li
   -maxInsertRequestSize size
     	The maximum size in bytes of a single Prometheus remote_write API request
     	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 33554432)
+  -maxLabelValueLen int
+    	The maximum length of label values in the accepted time series. Longer label values are truncated. In this case the vm_too_long_label_values_total metric at /metrics page is incremented (default 16384)
   -maxLabelsPerTimeseries int
-    	The maximum number of labels accepted per time series. Superfluous labels are dropped (default 30)
+    	The maximum number of labels accepted per time series. Superfluous labels are dropped. In this case the vm_metrics_with_dropped_labels_total metric at /metrics page is incremented (default 30)
   -memory.allowedBytes size
     	Allowed size of system memory VictoriaMetrics caches may occupy. This option overrides -memory.allowedPercent if set to a non-zero value. Too low a value may increase the cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from OS page cache resulting in higher disk IO usage
     	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 0)

app/vminsert/main.go

@@ -43,7 +43,8 @@ var (
 		"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")
 	configAuthKey          = flag.String("configAuthKey", "", "Authorization key for accessing /config page. It must be passed via authKey query arg")
-	maxLabelsPerTimeseries = flag.Int("maxLabelsPerTimeseries", 30, "The maximum number of labels accepted per time series. Superfluous labels are dropped")
+	maxLabelsPerTimeseries = flag.Int("maxLabelsPerTimeseries", 30, "The maximum number of labels accepted per time series. Superfluous labels are dropped. In this case the vm_metrics_with_dropped_labels_total metric at /metrics page is incremented")
+	maxLabelValueLen       = flag.Int("maxLabelValueLen", 16*1024, "The maximum length of label values in the accepted time series. Longer label values are truncated. In this case the vm_too_long_label_values_total metric at /metrics page is incremented")
 )
 
 var (
@@ -57,6 +58,7 @@ var (
 func Init() {
 	relabel.Init()
 	storage.SetMaxLabelsPerTimeseries(*maxLabelsPerTimeseries)
+	storage.SetMaxLabelValueLen(*maxLabelValueLen)
 	common.StartUnmarshalWorkers()
 	writeconcurrencylimiter.Init()
 	if len(*graphiteListenAddr) > 0 {

docs/CHANGELOG.md

@@ -9,6 +9,7 @@ sort: 15
 * FEATURE: [vmauth](https://docs.victoriametrics.com/vmauth.html): allow specifying `http` and `https` urls in `-auth.config` command-line flag. See [this pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/1898). Thanks for @TFM93 .
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): allow specifying `http` and `https` urls in the following command-line flags: `-promscrape.config`, `-remoteWrite.relabelConfig` and `-remoteWrite.urlRelabelConfig`.
 * FEATURE: vminsert: allow specifying `http` and `https` urls in `-relabelConfig` command-line flag.
+* FEATURE: vminsert: add `-maxLabelValueLen` command-line flag for the ability to configure the maximum length of label value. See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1908).
 
 * BUGFIX: fix `unaligned 64-bit atomic operation` panic on 32-bit architectures, which has been introduced in v1.70.0.
 

docs/README.md

@@ -1651,8 +1651,10 @@ Pass `-help` to VictoriaMetrics in order to see the list of supported command-li
   -maxInsertRequestSize size
     	The maximum size in bytes of a single Prometheus remote_write API request
     	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 33554432)
+  -maxLabelValueLen int
+    	The maximum length of label values in the accepted time series. Longer label values are truncated. In this case the vm_too_long_label_values_total metric at /metrics page is incremented (default 16384)
   -maxLabelsPerTimeseries int
-    	The maximum number of labels accepted per time series. Superfluous labels are dropped (default 30)
+    	The maximum number of labels accepted per time series. Superfluous labels are dropped. In this case the vm_metrics_with_dropped_labels_total metric at /metrics page is incremented (default 30)
   -memory.allowedBytes size
     	Allowed size of system memory VictoriaMetrics caches may occupy. This option overrides -memory.allowedPercent if set to a non-zero value. Too low a value may increase the cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from OS page cache resulting in higher disk IO usage
     	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 0)

docs/Single-server-VictoriaMetrics.md

@@ -1655,8 +1655,10 @@ Pass `-help` to VictoriaMetrics in order to see the list of supported command-li
   -maxInsertRequestSize size
     	The maximum size in bytes of a single Prometheus remote_write API request
     	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 33554432)
+  -maxLabelValueLen int
+    	The maximum length of label values in the accepted time series. Longer label values are truncated. In this case the vm_too_long_label_values_total metric at /metrics page is incremented (default 16384)
   -maxLabelsPerTimeseries int
-    	The maximum number of labels accepted per time series. Superfluous labels are dropped (default 30)
+    	The maximum number of labels accepted per time series. Superfluous labels are dropped. In this case the vm_metrics_with_dropped_labels_total metric at /metrics page is incremented (default 30)
   -memory.allowedBytes size
     	Allowed size of system memory VictoriaMetrics caches may occupy. This option overrides -memory.allowedPercent if set to a non-zero value. Too low a value may increase the cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from OS page cache resulting in higher disk IO usage
     	Supports the following optional suffixes for size values: KB, MB, GB, KiB, MiB, GiB (default 0)

lib/storage/metric_name.go

@@ -418,7 +418,18 @@ const maxLabelNameLen = 256
 // The maximum length of label value.
 //
 // Longer values are truncated.
-const maxLabelValueLen = 16 * 1024
+var maxLabelValueLen = 16 * 1024
+
+// SetMaxLabelValueLen sets the limit on the label value length.
+//
+// This function can be called before using the storage package.
+//
+// Label values with longer length are truncated.
+func SetMaxLabelValueLen(n int) {
+	if n > 0 {
+		maxLabelValueLen = n
+	}
+}
 
 // The maximum number of labels per each timeseries.
 var maxLabelsPerTimeseries = 30
@@ -426,12 +437,13 @@ var maxLabelsPerTimeseries = 30
 // SetMaxLabelsPerTimeseries sets the limit on the number of labels
 // per each time series.
 //
+// This function can be called before using the storage package.
+//
 // Superfluous labels are dropped.
 func SetMaxLabelsPerTimeseries(maxLabels int) {
-	if maxLabels <= 0 {
+	if maxLabels > 0 {
-		logger.Panicf("BUG: maxLabels must be positive; got %d", maxLabels)
+		maxLabelsPerTimeseries = maxLabels
 	}
-	maxLabelsPerTimeseries = maxLabels
 }
 
 // MarshalMetricNameRaw marshals labels to dst and returns the result.