FastAPI instrumenter not respecting traceparent sampling

Describe your environment

OS: Ubuntu & windows
Python version: 3.10
Package version: 1.6.7

What happened?

I am using Open Telemetry fast api intrumentor, where I want the logs to be correlated using w3c for incoming requests.

This works OK, so if I get a request that is forwarded from another service, the logs have the same operation ID when they are collected to azure.

But when the forwarded request has a traceparent header with the sample flag OFF (e.g 00-3e4cb418448aad7300ca890e7d1b3980-432829696627be4a-00), the fastapi instrumentation is still logging the backend operations to Azure.

Is this the expected outcome? I would like that it only logs requests that are marked not to be sampled in the traceparent, that it is also not logged in my fastapi app.

Steps to Reproduce

Send request to API with header traceparent with sample flag off (and env set OTEL_TRACES_SAMPLER="parentbased_always_off")

Expected Result

No logging in app/ sent to azure

Actual Result

Logs are sent for requests with header with sample flag both ON and OFF

Additional context

No response

Would you like to implement a fix?

None

Start with the FastAPI instrumentor and reproduce the request using a W3C traceparent header whose sample flag is off, together with OTEL_TRACES_SAMPLER="parentbased_always_off". Trace how sampling affects the request's emitted logs or telemetry, then verify that unsampled requests produce no app or Azure logs while sampled requests retain their current behavior.