Ensure trace context is propagated from incoming and to outgoing requests

[gaelreyrol]

We need to ensure trace context is propagated from incoming requests to current instrumentation and to outgoing requests.

[AtCliffUnderline]

@gaelreyrol hello! Sorry for bothering, but is it already works, or something should be done for trace to be propagated from incoming request? Maybe not understand ensure correctly :)
Having some troubles with it for now, so want to help if it is not works.

[AtCliffUnderline]

Not sure, maybe cause of this line:
https://github.com/FriendsOfOpenTelemetry/opentelemetry-bundle/blob/main/src/Resources/config/services_tracing_instrumentation.php#L57

[gaelreyrol]

Hi @AtCliffUnderline, I created this issue like a reminder that something needs to be done about this.

Currently, it does not work and it needs to be implemented in two parts:

From an incoming request, I need to collect trace context to reuse the trace id instead of creating a new one.
On an outgoing request, add trace context to allow another service to reuse it.

You will find documentation here: https://opentelemetry.io/docs/languages/php/propagation/.

It should be done by following the W3C Trace Context Recommendation.