OTLP: Remove experimental word form OTLP receiver (#14894)

The OTLP receiver can now considered stable. We've had it for longer
than a year in main and has received constant improvements.

Signed-off-by: Jesus Vazquez <jesusvzpg@gmail.com>

cmd/prometheus/main.go

@@ -182,9 +182,6 @@ func (c *flagConfig) setFeatureListOptions(logger log.Logger) error {
 		opts := strings.Split(f, ",")
 		for _, o := range opts {
 			switch o {
-			case "otlp-write-receiver":
-				c.web.EnableOTLPWriteReceiver = true
-				level.Info(logger).Log("msg", "Experimental OTLP write receiver enabled")
 			case "expand-external-labels":
 				c.enableExpandExternalLabels = true
 				level.Info(logger).Log("msg", "Experimental expand-external-labels enabled")
@@ -345,6 +342,9 @@ func main() {
 	a.Flag("web.remote-write-receiver.accepted-protobuf-messages", fmt.Sprintf("List of the remote write protobuf messages to accept when receiving the remote writes. Supported values: %v", supportedRemoteWriteProtoMsgs.String())).
 		Default(supportedRemoteWriteProtoMsgs.Strings()...).SetValue(rwProtoMsgFlagValue(&cfg.web.AcceptRemoteWriteProtoMsgs))
 
+	a.Flag("web.enable-otlp-receiver", "Enable API endpoint accepting OTLP write requests.").
+		Default("false").BoolVar(&cfg.web.EnableOTLPWriteReceiver)
+
 	a.Flag("web.console.templates", "Path to the console template directory, available at /consoles.").
 		Default("consoles").StringVar(&cfg.web.ConsoleTemplatesPath)
 
@@ -475,7 +475,7 @@ func main() {
 	a.Flag("scrape.discovery-reload-interval", "Interval used by scrape manager to throttle target groups updates.").
 		Hidden().Default("5s").SetValue(&cfg.scrape.DiscoveryReloadInterval)
 
-	a.Flag("enable-feature", "Comma separated feature names to enable. Valid options: auto-gomemlimit, exemplar-storage, expand-external-labels, memory-snapshot-on-shutdown, promql-per-step-stats, promql-experimental-functions, extra-scrape-metrics, auto-gomaxprocs, native-histograms, otlp-write-receiver, created-timestamp-zero-ingestion, concurrent-rule-eval, delayed-compaction, old-ui. See https://prometheus.io/docs/prometheus/latest/feature_flags/ for more details.").
+	a.Flag("enable-feature", "Comma separated feature names to enable. Valid options: auto-gomemlimit, exemplar-storage, expand-external-labels, memory-snapshot-on-shutdown, promql-per-step-stats, promql-experimental-functions, extra-scrape-metrics, auto-gomaxprocs, native-histograms, created-timestamp-zero-ingestion, concurrent-rule-eval, delayed-compaction, old-ui. See https://prometheus.io/docs/prometheus/latest/feature_flags/ for more details.").
 		Default("").StringsVar(&cfg.featureList)
 
 	a.Flag("agent", "Run Prometheus in 'Agent mode'.").BoolVar(&agentMode)

docs/command-line/prometheus.md

@@ -29,6 +29,7 @@ The Prometheus monitoring server
 | <code class="text-nowrap">--web.enable-admin-api</code> | Enable API endpoints for admin control actions. | `false` |
 | <code class="text-nowrap">--web.enable-remote-write-receiver</code> | Enable API endpoint accepting remote write requests. | `false` |
 | <code class="text-nowrap">--web.remote-write-receiver.accepted-protobuf-messages</code> | List of the remote write protobuf messages to accept when receiving the remote writes. Supported values: prometheus.WriteRequest, io.prometheus.write.v2.Request | `prometheus.WriteRequest` |
+| <code class="text-nowrap">--web.enable-otlp-receiver</code> | Enable API endpoint accepting OTLP write requests. | `false` |
 | <code class="text-nowrap">--web.console.templates</code> | Path to the console template directory, available at /consoles. | `consoles` |
 | <code class="text-nowrap">--web.console.libraries</code> | Path to the console library directory. | `console_libraries` |
 | <code class="text-nowrap">--web.page-title</code> | Document title of Prometheus instance. | `Prometheus Time Series Collection and Processing Server` |
@@ -57,7 +58,7 @@ The Prometheus monitoring server
 | <code class="text-nowrap">--query.timeout</code> | Maximum time a query may take before being aborted. Use with server mode only. | `2m` |
 | <code class="text-nowrap">--query.max-concurrency</code> | Maximum number of queries executed concurrently. Use with server mode only. | `20` |
 | <code class="text-nowrap">--query.max-samples</code> | Maximum number of samples a single query can load into memory. Note that queries will fail if they try to load more samples than this into memory, so this also limits the number of samples a query can return. Use with server mode only. | `50000000` |
-| <code class="text-nowrap">--enable-feature</code> <code class="text-nowrap">...<code class="text-nowrap"> | Comma separated feature names to enable. Valid options: auto-gomemlimit, exemplar-storage, expand-external-labels, memory-snapshot-on-shutdown, promql-per-step-stats, promql-experimental-functions, extra-scrape-metrics, auto-gomaxprocs, native-histograms, otlp-write-receiver, created-timestamp-zero-ingestion, concurrent-rule-eval, delayed-compaction, old-ui. See https://prometheus.io/docs/prometheus/latest/feature_flags/ for more details. |  |
+| <code class="text-nowrap">--enable-feature</code> <code class="text-nowrap">...<code class="text-nowrap"> | Comma separated feature names to enable. Valid options: auto-gomemlimit, exemplar-storage, expand-external-labels, memory-snapshot-on-shutdown, promql-per-step-stats, promql-experimental-functions, extra-scrape-metrics, auto-gomaxprocs, native-histograms, created-timestamp-zero-ingestion, concurrent-rule-eval, delayed-compaction, old-ui. See https://prometheus.io/docs/prometheus/latest/feature_flags/ for more details. |  |
 | <code class="text-nowrap">--agent</code> | Run Prometheus in 'Agent mode'. |  |
 | <code class="text-nowrap">--log.level</code> | Only log messages with the given severity or above. One of: [debug, info, warn, error] | `info` |
 | <code class="text-nowrap">--log.format</code> | Output format of log messages. One of: [logfmt, json] | `logfmt` |

docs/feature_flags.md

@@ -147,14 +147,6 @@ This should **only** be applied to metrics that currently produce such labels.
         regex: (\d+)\.0+;.*_bucket
 ```
 
-## OTLP Receiver
-
-`--enable-feature=otlp-write-receiver`
-
-The OTLP receiver allows Prometheus to accept [OpenTelemetry](https://opentelemetry.io/) metrics writes.
-Prometheus is best used as a Pull based system, and staleness, `up` metric, and other Pull enabled features
-won't work when you push OTLP metrics.
-
 ## Experimental PromQL functions
 
 `--enable-feature=promql-experimental-functions`

docs/querying/api.md

@@ -1388,8 +1388,8 @@ is not considered an efficient way of ingesting samples. Use it
 with caution for specific low-volume use cases. It is not suitable for
 replacing the ingestion via scraping.
 
-Enable the OTLP receiver by the feature flag
-`--enable-feature=otlp-write-receiver`. When enabled, the OTLP receiver
+Enable the OTLP receiver by setting
+`--web.enable-otlp-receiver`. When enabled, the OTLP receiver
 endpoint is `/api/v1/otlp/v1/metrics`.
 
 *New in v2.47*

web/api/v1/api.go

@@ -1750,7 +1750,7 @@ func (api *API) otlpWrite(w http.ResponseWriter, r *http.Request) {
 	if api.otlpWriteHandler != nil {
 		api.otlpWriteHandler.ServeHTTP(w, r)
 	} else {
-		http.Error(w, "otlp write receiver needs to be enabled with --enable-feature=otlp-write-receiver", http.StatusNotFound)
+		http.Error(w, "otlp write receiver needs to be enabled with --web.enable-otlp-receiver", http.StatusNotFound)
 	}
 }