Parent span propagation for Ory Hydra when using OpenTelemetry

[eirikeve]

Hi! Thanks for this great project.

We're self-hosting Hydra, and configured it for tracing with OpenTelemetry.

Collecting traces from Hydra works well. However, I'm encountering issues with trace propagation between upstream services and Hydra. So spans from Hydra don't appear as sub-spans of the root trace.

Here's a screenshot to illustrate. We perform a POST request to Hydra:

Here's the corresponding trace from Hydra:

The upstream service is a Java-app using hydra-client-java. It's instrumented with OTel's Java agent, which I believe uses W3C TraceContext for propagating traces by default. I see that hydra-client-java uses OkHttp, which should in theory be supported by OTel's Java autoinstrumentation. Traces to other downstream services are propagated as expected (but none of those requests use OkHttp).

From what I see in ory/x/otelx/otlp.go, the tracer used in Hydra should support W3C TraceContext. So I'm a bit confused as to why the propagation doesn't work as expected.

I know it's a long shot, but do you have any reference examples on configuring tracing when using OpenTelemetry, hydra-client-java, and Ory Hydra in Docker?
Or has anyone else managed to get trace propagation to work as expected between the client and Hydra?

Thanks for your time.

[eirikeve]

Just realized what causes this.

In case it helps anyone else: it was caused by using another format for propagating trace IDs. I'd completely forgotten 😮‍💨
So I was mistaken in the question when I said we use W3C.

The apps were actually using AWS X-Ray's X-Amzn-Trace-Id (-Dotel.propagators=xray) format. So that explains why tracing worked for requests between our own services but not for requests to Hydra.