Repository: grpc/grpc-go
File: examples/features/opentelemetry/client/main.go (Go)

Code before:
	"go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/trace"
	"go.opentelemetry.io/otel/sdk/trace/tracetest"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	"google.golang.org/grpc/examples/features/proto/echo"
	experimental "google.golang.org/grpc/experimental/opentelemetry"
	"google.golang.org/grpc/stats/opentelemetry"
)

var (
	addr               = flag.String("addr", ":50051", "the server address to connect to")
	prometheusEndpoint = flag.String("prometheus_endpoint", ":9465", "the Prometheus exporter endpoint")
)

func main() {
	exporter, err := prometheus.New()
	if err != nil {
		log.Fatalf("Failed to start prometheus exporter: %v", err)
	}
	provider := metric.NewMeterProvider(metric.WithReader(exporter))

	spanExporter := tracetest.NewInMemoryExporter()
	spanProcessor := trace.NewSimpleSpanProcessor(spanExporter)
	tracerProvider := trace.NewTracerProvider(trace.WithSpanProcessor(spanProcessor))
	textMapPropagator := propagation.NewCompositeTextMapPropagator(opentelemetry.GRPCTraceBinPropagator{})
	traceOptions := experimental.TraceOptions{
		TracerProvider:    tracerProvider,
		TextMapPropagator: textMapPropagator,
	}

	go func() {
		log.Printf("Starting Prometheus metrics server at %s\n", *prometheusEndpoint)
		if err := http.ListenAndServe(*prometheusEndpoint, promhttp.Handler()); err != nil {
			log.Fatalf("Failed to start Prometheus server: %v", err)
		}
	}()

	ctx := context.Background()
	do := opentelemetry.DialOption(opentelemetry.Options{
		MetricsOptions: opentelemetry.MetricsOptions{MeterProvider: provider},
		TraceOptions:   traceOptions})

	cc, err := grpc.NewClient(*addr, grpc.WithTransportCredentials(insecure.NewCredentials()), do)
	if err != nil {
		log.Fatalf("Failed to create a client: %v", err)
	}
	defer cc.Close()
	c := echo.NewEchoClient(cc)

	// Make an RPC every second. This should trigger telemetry on prometheus

Review comment (suggestion):
For main example, we should be using only `W3CContextPropagator`. We will have separate example for opencensus migration, where we can showcase the `GRPCTraceBinPropagator`

Code after:
	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"
)

var (
	addr               = flag.String("addr", ":50051", "the server address to connect to")
	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)
	}
	// 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},
	})

	go http.ListenAndServe(*prometheusEndpoint, promhttp.Handler())

	cc, err := grpc.NewClient(*addr, grpc.WithTransportCredentials(insecure.NewCredentials()), do)
	if err != nil {
		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.
	for {
		r, err := c.UnaryEcho(ctx, &echo.EchoRequest{Message: "this is examples/opentelemetry"})