Context propagation differences

[mat-rumian]

I've observed many differences in case of context propagation between instrumentations and type of invoke.

Reqs:

• AWS XRAY Disabled on lambdas
• OTEL_TRACES_SAMPLER = always_on

Instrumentation	INSTRUMENTED CALL - CLIENT XRAY PROPAGATION SET	INSTRUMENTED CALL - CLIENT NO XRAY	NOT INSTRUMENTED CALL
Python (invoke)	Single trace, context propagated	Two traces are created, context not propagated, lambda trace root span pointing to the unknown parent	Single trace, root span pointing to unknown parent
NodeJS (invoke)	Single trace, context propagated	Two traces created, context not propagated, lambda trace root span pointing to the unknown parent	Single trace, root span pointing to unknown parent
Java Wrapper (invoke)	Single trace, context propagated	Two traces create (client, lambda), lambda trace root span is correct. There's no unknown parent span.	Single trace created, root span doesn't have a parent
-------------	-------------	-------------	-------------
Python (API CURL)	Single trace, context propagated, but lambda span points to unknown parent	Two traces are created, context not propagated, lambda trace root span pointing to the unknown parent	Single trace, root span pointing to unknown parent
NodeJS (API CURL)	Single trace, context propagated, but lambda span points to unknown parent	Single trace, context propagated	Single trace, root span pointing to unknown parent
Java Wrapper (API CURL)	Single trace, context propagated, but lambda span points to unknown parent	Single trace, context propagated	Single trace created, root span doesn't have a parent

I think the way it should work for OT in this case should be:

• not instrumented call to the lambda should generate single trace without parent in root span (e.g. if OTEL_TRACES_SAMPLER=always_on)
• instrumented call to the lambda should generate single trace with context propagated