How trace gRPC service (server side) using collector

[victorpacheco3107]

Hi.
I'm using a collector to trace my spans in my java services, this serivces are http and grpc. The collector endpoint is localhost:55680. This java services trace succesfully.

Now, I want to use this collector to trace my go service based on gRPC.

In my go service, I copy this files: interceptor.go and grpctrace.go from repo opentelemetry-go-contrib, here https://github.com/open-telemetry/opentelemetry-go-contrib/tree/main/instrumentation/google.golang.org/grpc/otelgrpc

Now, I create a file called config.go:

package grpcTracing

import (
  "context"
  "log"

  "go.opentelemetry.io/otel"
  "go.opentelemetry.io/otel/exporters/otlp"
  "go.opentelemetry.io/otel/exporters/otlp/otlpgrpc"
  "go.opentelemetry.io/otel/label"
  "go.opentelemetry.io/otel/propagation"
  "go.opentelemetry.io/otel/sdk/resource"
  sdktrace "go.opentelemetry.io/otel/sdk/trace"
)

// Init configures an OpenTelemetry exporter and trace provider
func InitTracing() {

  ctx := context.Background()

  driver := otlpgrpc.NewDriver(
    otlpgrpc.WithInsecure(),
    otlpgrpc.WithEndpoint("localhost:55680"),
  )

  exporter, err := otlp.NewExporter(ctx, driver) // Configure as needed.
  if err != nil {
    log.Fatal(err)
  }
  defer func() {
    err := exporter.Shutdown(ctx)
    if err != nil {
      log.Fatalf("failed to stop exporter: %v", err)
    }
  }()

  service := "test-service"

  tracerProvider := sdktrace.NewTracerProvider(
    sdktrace.WithConfig(sdktrace.Config{DefaultSampler: sdktrace.AlwaysSample()}),
    sdktrace.WithResource(resource.NewWithAttributes(
      label.Key("service.name").String(service),
    )),
    sdktrace.WithBatcher(exporter),
  )


  if err != nil {
    log.Fatal(err)
  }
  otel.SetTracerProvider(tracerProvider)
  otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
}

Now, when I start my gRPC server, I do this:

        grpcTracing.InitTracing()
        ...
	grpcServer := grpc.NewServer(
		grpc.UnaryInterceptor(grpcTracing.UnaryServerInterceptor()),
	)

This is the server interceptor, this is called every petition:

func UnaryServerInterceptor(opts ...Option) grpc.UnaryServerInterceptor {
  return func(
    ctx context.Context,
    req interface{},
    info *grpc.UnaryServerInfo,
    handler grpc.UnaryHandler,
  ) (interface{}, error) {
    requestMetadata, _ := metadata.FromIncomingContext(ctx)
    metadataCopy := requestMetadata.Copy()

    entries, spanCtx := Extract(ctx, &metadataCopy, opts...)
    ctx = baggage.ContextWithValues(ctx, entries...)

    tracer := newConfig(opts).TracerProvider.Tracer(
      instrumentationName,
      trace.WithInstrumentationVersion(otelcontrib.SemVersion()),
    )

    name, attr := spanInfo(info.FullMethod, peerFromCtx(ctx))
    ctx, span := tracer.Start(
      trace.ContextWithRemoteSpanContext(ctx, spanCtx),
      name,
      trace.WithSpanKind(trace.SpanKindServer),
      trace.WithAttributes(attr...),
    )
    defer span.End()

    messageReceived.Event(ctx, 1, req)

    resp, err := handler(ctx, req)
    if err != nil {
      s, _ := status.FromError(err)
      span.SetStatus(codes.Error, s.Message())
      span.SetAttributes(statusCodeAttr(s.Code()))
      messageSent.Event(ctx, 1, s.Proto())
    } else {
      span.SetAttributes(statusCodeAttr(grpc_codes.OK))
      messageSent.Event(ctx, 1, resp)
    }

    return resp, err
  }
}

The first petition, I get this message:
rpc error: code = Canceled desc = context canceled
For the nexts petitions, I get this message:
exporter disconnected

I check the collector log, and It seems that no request comes.

Any idea why it doesn't work? What am I doing wrong?

Thanks!!!

[victorpacheco3107]

My error is in this lines:

defer func() {
    err := exporter.Shutdown(ctx)
    if err != nil {
      log.Fatalf("failed to stop exporter: %v", err)
    }
}()

I removed this line and it worked!