🐛 Fix OpentelemetryFinch handler on Finch.stream_while

[rparcus]

Fixes #327

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: rparcus / name: Robert Parcus (91808de, fb5d2d1, 7e0208c, 9ac5b88, 2fac77e)

[rparcus]

Hello 👋
Without this fix it is impossible to instrument anything that uses streaming + finch.
Is there anything I can do to further help with the review process?

[rparcus]

The main issue was here. Not every response contains a status key as it depends on the implementation of the streaming callback functions.

A fallback case is also added. In this fix, I'm not trying to come up with a general solution but just one that works for the patterns I saw. The tests use callbacks that return values in the patterns I was already working with.

[lud-wj]

I guess you could just match on the presence of the status:

case meta.result do
  {:ok, %{status: status}} when is_integer(status) -> status
  {:ok, {_request, %{status: status}}} when is_integer(status) -> status
  {:ok, {status, _headers, _body}} when is_integer(status) -> status
  _ -> 0
end

Because there is a risk that even when response is a map, response.status may not be set. As far as I can tell that part of the event is the stream accumulator and it could be anything, any term.

[lud-wj]

(edit fixed my clauses 😅 )

[lud-wj]

+1 for this PR.

We are using the Langchain lib with streams, and it is not compatible with OTEL.

[rparcus]

Thanks for the suggestion above. I think it's great @lud-wj.
Done in 9ac5b88

+1 for this PR.

We are using the Langchain lib with streams, and it is not compatible with OTEL.

That is exactly why this PR exists ✨