[BUG] Cannot Override OpenTelemetry Service Name or Version

[mikelly-psat]

Observed behavior

Despite being suggested via the documentation:

https://flagd.dev/reference/monitoring/#custom-resource-attributes

You can't override all resource attributes.

At least, I've seen that service.name and service.version seem to be basically hard-coded in.

Expected Behavior

The service would follow the typical OTEL conventions, and allow these resource attributes to be overridden by environment variables.

I am running flagd as a sidecar to a service right now, and want to be able to distinguish that instance of flagd from others we'll be running in the future with different configurations.

Steps to reproduce

Run Flagd via docker-compose with a service like this, with an otel collector also running locally:

  flagd:
    image: ghcr.io/open-feature/flagd:v0.15.2
    environment:
      OTEL_EXPORTER_OTLP_ENDPOINT: http://otel-collector-contrib:4317
      OTEL_EXPORTER_OTLP_PROTOCOL: grpc
      OTEL_RESOURCE_ATTRIBUTES: deployment.environment.name=laptop2,service.name=flagd2,service.version=0.15.2-fake,service.namespace=pretend,fake.attribute=fakeness
    command:
      - 'start'
      - '--uri'
      - 'file:/flags/flagd.json'
      - '--metrics-exporter'
      - 'otel'
    volumes:
      - ./flagd.json:/flags/flagd.json
    ports:
      - "8013:8013"

All attributes there in OTEL_RESOURCE_ATTRIBUTES are respected, other than the service.name and service.version.

[mikelly-psat]

I'm not very familiar with go, but I think the problem comes in here where svcName and version constants are used:

flagd/flagd/pkg/runtime/from_config.go

Line 71 in 5fa86c6

err := telemetry.BuildTraceProvider(context.Background(), logger, svcName, version, telCfg)

And then in the telemetry builder, that gets unconditionally passed to the resource:

flagd/core/pkg/telemetry/builder.go

Lines 153 to 169 in 5fa86c6

	// buildResourceFor builds a resource identifier with set of resources and service key as attributes
	func buildResourceFor(ctx context.Context, serviceName string, serviceVersion string) (*resource.Resource, error) {
	r, err := resource.New(
	ctx,
	resource.WithOS(),
	resource.WithHost(),
	resource.WithProcessRuntimeVersion(),
	resource.WithTelemetrySDK(),
	resource.WithAttributes(
	semconv.ServiceNameKey.String(serviceName),
	semconv.ServiceVersionKey.String(serviceVersion)),
	)
	if err != nil {
	return nil, fmt.Errorf("unable to create resource identifier: %w", err)
	}
	return r, nil
	}

From reading https://opentelemetry.io/docs/languages/go/resources/, it looks like we may just need to add resource.WithFromEnv(), to that call, or possibly leveraging resource.Merge()?