Unable to correlate spans with tracing-opentelemetry

[davidbarsky]

Hi folks, I found this old issue and I'm trying to get trucing-opentelemetry and Jaeger to work together. I am able to get spans into Jaeger, however I cannot find a way to tie the spans together with trace propagation. I'm trying to use code like the following:

let context = global::get_text_map_propagator(|propagator| propagator.extract(&carrier))
span.set_parent(context);

Does it matter what is in the hashmap in carrier?

Thanks.

Originally posted by @velvia in #89 (comment)

[davidbarsky]

Does it matter what is in the hashmap in carrier?

@velvia: Yes. The HashMap in the carrier should have the trace ID that you're looking to correlate. Can you post more of your code? How closely are you following this documentation?

[velvia]

@davidbarsky I'm following the example pretty closely. Actually the example does not have anything in the hash map, which is the critical part. My code is like this:

    let mut carrier = HashMap::new();
    carrier.insert("traceparent".to_string(), hex::encode(digest.0));
    global::get_text_map_propagator(|propagator| propagator.extract(&carrier))

You are probably wondering what digest is. Does the trace parent really need to be a preexisting trace ID, or could it be anything used to tie different spans together?
Are there any other fields that are needed?

Thanks.