Ensure traceID is propagated with Inject

[willyyang]

Hi, I'm hoping to understand whether I've injected the X-Datadog-Trace-Id of a span correctly in the carrier with the following code...

carrier := opentracing.HTTPHeadersCarrier(http.Header{})
mySpanContext := opentracing.SpanFromContext(ctx).Context()
opentracing.GlobalTracer().Inject(mySpanContext, opentracing.HTTPHeaders, carrier)

Can I be sure that the traceID of mySpanContext is the same as the one in carrier's X-Datadog-Trace-Id field?

I've extracted the headers from my other service and I see that two spans show up on DD with parent/child relationships.. can we assume that their traceIDs are the same and the X-Datadog-Parent-Id of the child span is the SpanID of the parent span?

Thanks in advance.

[yurishkuro]

Whether it's datadog or whatever header is the question of which tracer implementation you're using.

Your code has one issue - you're creating an empty instance of http.Header{} which is thrown away. So nothing actually gets into the request. You need to use the headers associated with the request.

[willyyang]

Thanks for the response. I'm using gRPC metadata to send the span's context across to another service.. just using Inject to get the traceID and parentID since #188 doesn't seem to be moving forward.