[opentelemetry] Split enable_opentelemetry into enable_metrics and enable_tracing

NEXT_RELEASE_NOTES.md

@@ -46,6 +46,8 @@ The release notes should contain at least the following sections:
 
 ## Optional migration tasks
 
+* `enable_opentelemetry` has been splited into two flags: `enable_metrics` and `enable_tracing`
+
 ## Important information
 
 * Fixed a bug where the `evict` command ignored entries without a locality. If your DSS instance does not have a locality set, the next `evict` run may be slow while it processes the backlog of old entries.

cmds/core-service/main.go

@@ -55,8 +55,9 @@ var (
 	logLevel                = flag.String("log_level", logging.DefaultLevel.String(), "The log level")
 	dumpRequests            = flag.Bool("dump_requests", false, "Log full HTTP request and response (note: will dump sensitive information to logs; intended only for debugging and/or development)")
 	profServiceName         = flag.String("gcp_prof_service_name", "", "Service name for the Go profiler")
-	enableOpenTelemetry     = flag.Bool("enable_opentelemetry", false, "Enable OpenTelemetry, including traces and activation metric endpoint")
-	metricsListeningAddress = flag.String("metrics_addr", ":8079", "Address and port that the OpenTelemetry prometheus service binds to and listens on for incoming connections")
+	enableMetrics           = flag.Bool("enable_metrics", false, "Enable metric endpoint")
+	enableTracing           = flag.Bool("enable_tracing", false, "Enable tracing")
+	metricsListeningAddress = flag.String("metrics_addr", ":8079", "Address and port that the for the prometheus-compatible metric service binds to and listens on for incoming connections")
 
 	pkFile            = flag.String("public_key_files", "", "Path to public Keys to use for JWT decoding, separated by commas.")
 	jwksEndpoint      = flag.String("jwks_endpoint", "", "URL pointing to an endpoint serving JWKS")
@@ -120,7 +121,7 @@ func createRIDServers(ctx context.Context, locality string, logger *zap.Logger)
 		return nil, nil, stacktrace.Propagate(err, "Unable to interact with store")
 	}
 
-	if *enableOpenTelemetry {
+	if *enableMetrics {
 		err = registerRIDMetrics(ctx, ridStore)
 
 		if err != nil {
@@ -147,7 +148,7 @@ func createSCDServer(ctx context.Context, logger *zap.Logger) (*scd.Server, erro
 		return nil, err
 	}
 
-	if *enableOpenTelemetry {
+	if *enableMetrics {
 		err = registerSCDMetrics(ctx, scdStore)
 
 		if err != nil {
@@ -339,7 +340,7 @@ func RunHTTPServer(ctx context.Context, ctxCanceler func(), address, locality st
 	handler = authorizer.TokenMiddleware(handler)
 	handler = timeoutMiddleware(*timeout, handler)
 
-	if *enableOpenTelemetry {
+	if *enableMetrics || *enableTracing {
 		// We use the default settings; the APIRouter handler will override the span value accordingly, as it has more information.
 		handler = otelhttp.NewHandler(handler, "http")
 	}
@@ -454,8 +455,8 @@ func main() {
 	}
 
 	// Set up OpenTelemetry.
-	if *enableOpenTelemetry {
-		otelShutdown, err := setupOTelSDK(ctx, *metricsListeningAddress)
+	if *enableMetrics || *enableTracing {
+		otelShutdown, err := setupOTelSDK(ctx, *enableMetrics, *enableTracing, *metricsListeningAddress)
 		if err != nil {
 			logger.Panic("Failed to initialize OpenTelemetry", zap.Error(err))
 		}

cmds/core-service/otel.go

@@ -23,28 +23,42 @@ import (
 
 // setupOTelSDK bootstraps the OpenTelemetry pipeline.
 // If it does not return an error, make sure to call shutdown for proper cleanup.
-func setupOTelSDK(ctx context.Context, metricsListeningAddress string) (func(context.Context) error, error) {
+func setupOTelSDK(ctx context.Context, enableMetrics bool, enableTracing bool, metricsListeningAddress string) (func(context.Context) error, error) {
 
 	// Set up propagator.
 	prop := newPropagator()
 	otel.SetTextMapPropagator(prop)
 
-	// Set up trace provider.
-	tracerProvider, err := newTracerProvider(ctx)
-	if err != nil {
-		return nil, err
+	var tracerProvider *trace.TracerProvider
+	var meterProvider *metric.MeterProvider
+
+	if enableTracing {
+		// Set up trace provider.
+		tracerProvider, err := newTracerProvider(ctx)
+		if err != nil {
+			return nil, err
+		}
+		otel.SetTracerProvider(tracerProvider)
 	}
-	otel.SetTracerProvider(tracerProvider)
 
-	// Set up metrics exporter
-	meterProvider, err := newMeterProvider(ctx, metricsListeningAddress)
-	if err != nil {
-		return nil, err
+	if enableMetrics {
+		// Set up metrics exporter
+		meterProvider, err := newMeterProvider(ctx, metricsListeningAddress)
+		if err != nil {
+			return nil, err
+		}
+		otel.SetMeterProvider(meterProvider)
 	}
-	otel.SetMeterProvider(meterProvider)
 
 	shutdown := func(ctx context.Context) error {
-		return errors.Join(tracerProvider.Shutdown(ctx), meterProvider.Shutdown(ctx))
+		var err error
+		if tracerProvider != nil {
+			err = errors.Join(err, tracerProvider.Shutdown(ctx))
+		}
+		if meterProvider != nil {
+			err = errors.Join(err, meterProvider.Shutdown(ctx))
+		}
+		return err
 	}
 	return shutdown, nil
 }

docs/operations/monitoring.md

@@ -137,15 +137,17 @@ You can enable it on the DSS server to get:
 * Tracing for all queries
 * A Prometheus endpoint with some metrics
 
-Currently, this setting is not yet available in Terraform, Helm or Tanka.
+Currently, thoses settings are not yet available in Terraform, Helm or Tanka.
 
 !!! warning
 
-    By default, when OpenTelemetry is enabled, the metrics service listens on all addresses.
+    By default, when metrics are enabled, the metrics service listens on all addresses.
 
 
 ### Metrics
 
+Use flag `--enable_metrics` to enable metrics.
+
 Point any Prometheus server to the endpoint (by default on port 8079).
 
 You can use the `--metrics_addr` flag to change the listening port and address.
@@ -154,6 +156,8 @@ No dashboard has been created yet, but one is planned.
 
 ### Tracing
 
+Use flag `--enable_tracing` to enable tracing.
+
 Traces can be sent to any OpenTelemetry-compliant service. Self-hostable examples include [Jaeger](https://www.jaegertracing.io/), [OpenObserve](https://github.com/openobserve/openobserve), [Grafana Tempo](https://grafana.com/docs/tempo/latest/), and [SigNoz](https://github.com/SigNoz/signoz). Multiple SaaS solutions are also available (including some of the previously mentioned tools).
 
 You need to use the `OTEL_EXPORTER_OTLP_ENDPOINT` environment variable to configure it. Point it toward your server by following its specific documentation.
@@ -202,6 +206,6 @@ index f09bda59..8c96cf3e 100755
    -locality local_dev \
 -  -public_endpoint http://127.0.0.1:8082
 +  -public_endpoint http://127.0.0.1:8082 \
-+  -enable_opentelemetry
++  -enable_tracing
  fi
 ```