FastAPI instrumentation reports response code as 0

[cecheta]

• Package Name: azure-monitor-opentelemetry
• Package Version: 1.6.5
• Operating System: Windows (WSL2)
• Python Version: 3.12.9

Describe the bug
I noticed that the FastAPI instrumentation reports the response status code as 0 when an exception is thrown.

To Reproduce
Steps to reproduce the behavior:

1. Run https://github.com/Azure/azure-sdk-for-python/blob/23163bcb045d3564f8419fdf99eaef99e0642e5b/sdk/monitor/azure-monitor-opentelemetry/samples/tracing/http_fastapi.py
2. Send request to http://127.0.0.1:8008/exception

Expected behavior
Request with Response Code 500 is logged in Application Insights

Actual behavior
Response code is 0

Screenshots

[github-actions]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @hectorhdzg @jeremydvoss @lzchen.

[lzchen]

The asgi middleware (which the fastapi instrumentation depends on) does not handle uncaught exceptions. This is why the status code that is return is set to 0 since there is no response back from the server. I would open up an issue in upstream OpenTelemetry to request a the middleware to handle uncaught exceptions gracefully and to set status code to 500 if such exceptions occur.

[cecheta]

Ok, thanks