examples/features/opentelemetry: demonstrate tracing using OpenTelemetry plugin

examples/features/opentelemetry/README.md

@@ -1,7 +1,7 @@
 # OpenTelemetry
 
-This example shows how to configure OpenTelemetry on a client and server, and shows
-what type of telemetry data it can produce for certain RPC's.
+This example shows how to configure OpenTelemetry on a client and server, and
+shows what type of telemetry data it can produce for certain RPCs.
 
 ## Try it
 
@@ -20,13 +20,18 @@ curl localhost:9465/metrics
 
 ## Explanation
 
-The client continuously makes RPC's to a server. The client and server both
+The client continuously makes RPCs to a server. The client and server both
 expose a prometheus exporter to listen and provide metrics. This defaults to
-:9464 for the server and :9465 for the client.
+:9464 for the server and :9465 for the client. The client and server are also
+configured to output traces directly to their standard output streams using
+`stdouttrace`.
 
 OpenTelemetry is configured on both the client and the server, and exports to
 the Prometheus exporter. The exporter exposes metrics on the Prometheus ports
-described above.
+described above. OpenTelemetry exports traces using the `stdouttrace` exporter,
+which prints structured trace data to the console output of both the client and
+server. Each RPC call produces trace information that captures the execution
+flow and timing of operations.
 
 Curling to the exposed Prometheus ports outputs the metrics recorded on the
 client and server.

examples/features/opentelemetry/client/main.go

@@ -27,38 +27,55 @@ import (
 	"net/http"
 	"time"
 
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"go.opentelemetry.io/otel/exporters/prometheus"
+	otelstdouttrace "go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
+	otelpropagation "go.opentelemetry.io/otel/propagation"
+	otelmetric "go.opentelemetry.io/otel/sdk/metric"
+	otelresource "go.opentelemetry.io/otel/sdk/resource"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 	"google.golang.org/grpc/examples/features/proto/echo"
+	oteltracing "google.golang.org/grpc/experimental/opentelemetry"
 	"google.golang.org/grpc/stats/opentelemetry"
-
-	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"go.opentelemetry.io/otel/exporters/prometheus"
-	"go.opentelemetry.io/otel/sdk/metric"
 )
 
 var (
 	addr               = flag.String("addr", ":50051", "the server address to connect to")
-	prometheusEndpoint = flag.String("prometheus_endpoint", ":9465", "the Prometheus exporter endpoint")
+	prometheusEndpoint = flag.String("prometheus_endpoint", ":9465", "the Prometheus exporter endpoint for metrics")
 )
 
 func main() {
 	exporter, err := prometheus.New()
 	if err != nil {
 		log.Fatalf("Failed to start prometheus exporter: %v", err)
 	}
-	provider := metric.NewMeterProvider(metric.WithReader(exporter))
-	go http.ListenAndServe(*prometheusEndpoint, promhttp.Handler())
+	// Configure meter provider for metrics
+	meterProvider := otelmetric.NewMeterProvider(otelmetric.WithReader(exporter))
+	// Configure exporter for traces
+	traceExporter, err := otelstdouttrace.New(otelstdouttrace.WithPrettyPrint())
+	if err != nil {
+		log.Fatalf("Failed to create stdouttrace exporter: %v", err)
+	}
+	traceProvider := sdktrace.NewTracerProvider(sdktrace.WithBatcher(traceExporter), sdktrace.WithResource(otelresource.NewWithAttributes(semconv.SchemaURL, semconv.ServiceName("grpc-client"))))
+	// Configure W3C Trace Context Propagator for traces
+	textMapPropagator := otelpropagation.TraceContext{}
+	do := opentelemetry.DialOption(opentelemetry.Options{
+		MetricsOptions: opentelemetry.MetricsOptions{MeterProvider: meterProvider},
+		TraceOptions:   oteltracing.TraceOptions{TracerProvider: traceProvider, TextMapPropagator: textMapPropagator},
+	})
 
-	ctx := context.Background()
-	do := opentelemetry.DialOption(opentelemetry.Options{MetricsOptions: opentelemetry.MetricsOptions{MeterProvider: provider}})
+	go http.ListenAndServe(*prometheusEndpoint, promhttp.Handler())
 
 	cc, err := grpc.NewClient(*addr, grpc.WithTransportCredentials(insecure.NewCredentials()), do)
 	if err != nil {
-		log.Fatalf("Failed to start NewClient: %v", err)
+		log.Fatalf("grpc.NewClient() failed: %v", err)
 	}
 	defer cc.Close()
 	c := echo.NewEchoClient(cc)
+	ctx := context.Background()
 
 	// Make an RPC every second. This should trigger telemetry to be emitted from
 	// the client and the server.

examples/features/opentelemetry/server/main.go

@@ -27,18 +27,23 @@ import (
 	"net"
 	"net/http"
 
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"go.opentelemetry.io/otel/exporters/prometheus"
+	otelstdouttrace "go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
+	otelpropagation "go.opentelemetry.io/otel/propagation"
+	otelmetric "go.opentelemetry.io/otel/sdk/metric"
+	otelresource "go.opentelemetry.io/otel/sdk/resource"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
 	"google.golang.org/grpc"
 	pb "google.golang.org/grpc/examples/features/proto/echo"
+	oteltracing "google.golang.org/grpc/experimental/opentelemetry"
 	"google.golang.org/grpc/stats/opentelemetry"
-
-	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"go.opentelemetry.io/otel/exporters/prometheus"
-	"go.opentelemetry.io/otel/sdk/metric"
 )
 
 var (
 	addr               = flag.String("addr", ":50051", "the server address to connect to")
-	prometheusEndpoint = flag.String("prometheus_endpoint", ":9464", "the Prometheus exporter endpoint")
+	prometheusEndpoint = flag.String("prometheus_endpoint", ":9464", "the Prometheus exporter endpoint for metrics")
 )
 
 type echoServer struct {
@@ -55,10 +60,21 @@ func main() {
 	if err != nil {
 		log.Fatalf("Failed to start prometheus exporter: %v", err)
 	}
-	provider := metric.NewMeterProvider(metric.WithReader(exporter))
-	go http.ListenAndServe(*prometheusEndpoint, promhttp.Handler())
+	// Configure meter provider for metrics
+	meterProvider := otelmetric.NewMeterProvider(otelmetric.WithReader(exporter))
+	// Configure exporter for traces
+	traceExporter, err := otelstdouttrace.New(otelstdouttrace.WithPrettyPrint())
+	if err != nil {
+		log.Fatalf("Failed to create stdouttrace exporter: %v", err)
+	}
+	traceProvider := sdktrace.NewTracerProvider(sdktrace.WithBatcher(traceExporter), sdktrace.WithResource(otelresource.NewWithAttributes(semconv.SchemaURL, semconv.ServiceName("grpc-server"))))
+	// Configure W3C Trace Context Propagator for traces
+	textMapPropagator := otelpropagation.TraceContext{}
+	so := opentelemetry.ServerOption(opentelemetry.Options{
+		MetricsOptions: opentelemetry.MetricsOptions{MeterProvider: meterProvider},
+		TraceOptions:   oteltracing.TraceOptions{TracerProvider: traceProvider, TextMapPropagator: textMapPropagator}})
 
-	so := opentelemetry.ServerOption(opentelemetry.Options{MetricsOptions: opentelemetry.MetricsOptions{MeterProvider: provider}})
+	go http.ListenAndServe(*prometheusEndpoint, promhttp.Handler())
 
 	lis, err := net.Listen("tcp", *addr)
 	if err != nil {

examples/go.mod

@@ -5,7 +5,10 @@ go 1.23.0
 require (
 	github.com/cncf/xds/go v0.0.0-20250326154945-ae57f3c0d45f
 	github.com/prometheus/client_golang v1.21.1
+	go.opentelemetry.io/otel v1.35.0
 	go.opentelemetry.io/otel/exporters/prometheus v0.57.0
+	go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.35.0
+	go.opentelemetry.io/otel/sdk v1.35.0
 	go.opentelemetry.io/otel/sdk/metric v1.35.0
 	golang.org/x/oauth2 v0.28.0
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20250324211829-b45e905df463
@@ -68,9 +71,7 @@ require (
 	go.opentelemetry.io/contrib/detectors/gcp v1.35.0 // indirect
 	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.60.0 // indirect
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.60.0 // indirect
-	go.opentelemetry.io/otel v1.35.0 // indirect
 	go.opentelemetry.io/otel/metric v1.35.0 // indirect
-	go.opentelemetry.io/otel/sdk v1.35.0 // indirect
 	go.opentelemetry.io/otel/trace v1.35.0 // indirect
 	golang.org/x/crypto v0.36.0 // indirect
 	golang.org/x/net v0.38.0 // indirect

examples/go.sum

@@ -1151,6 +1151,8 @@ go.opentelemetry.io/otel v1.35.0 h1:xKWKPxrxB6OtMCbmMY021CqC45J+3Onta9MqjhnusiQ=
 go.opentelemetry.io/otel v1.35.0/go.mod h1:UEqy8Zp11hpkUrL73gSlELM0DupHoiq72dR+Zqel/+Y=
 go.opentelemetry.io/otel/exporters/prometheus v0.57.0 h1:AHh/lAP1BHrY5gBwk8ncc25FXWm/gmmY3BX258z5nuk=
 go.opentelemetry.io/otel/exporters/prometheus v0.57.0/go.mod h1:QpFWz1QxqevfjwzYdbMb4Y1NnlJvqSGwyuU0B4iuc9c=
+go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.35.0 h1:T0Ec2E+3YZf5bgTNQVet8iTDW7oIk03tXHq+wkwIDnE=
+go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.35.0/go.mod h1:30v2gqH+vYGJsesLWFov8u47EpYTcIQcBjKpI6pJThg=
 go.opentelemetry.io/otel/metric v1.32.0/go.mod h1:jH7CIbbK6SH2V2wE16W05BHCtIDzauciCRLoc/SyMv8=
 go.opentelemetry.io/otel/metric v1.35.0 h1:0znxYu2SNyuMSQT4Y9WDWej0VpcsxkuklLa4/siN90M=
 go.opentelemetry.io/otel/metric v1.35.0/go.mod h1:nKVFgxBZ2fReX6IlyW28MgZojkoAkJGaE8CpgeAU3oE=
@@ -1165,6 +1167,7 @@ go.opentelemetry.io/proto/otlp v0.7.0/go.mod h1:PqfVotwruBrMGOCsRd/89rSnXhoiJIqe
 go.opentelemetry.io/proto/otlp v0.15.0/go.mod h1:H7XAot3MsfNsj7EXtrA2q5xSNQ10UqI405h3+duxN4U=
 go.opentelemetry.io/proto/otlp v0.19.0/go.mod h1:H7XAot3MsfNsj7EXtrA2q5xSNQ10UqI405h3+duxN4U=
 go.opentelemetry.io/proto/otlp v1.0.0/go.mod h1:Sy6pihPLfYHkr3NkUbEhGHFhINUSI/v80hjKIs5JXpM=
+go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
 go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=