feat: warn if LangfuseTracer initialized without tracing enabled

[isfuku]

Related Issues

• fixes Warn if LangfuseTracer initialized without HAYSTACK_CONTENT_TRACING_ENABLED #1230

Proposed Changes:

Add a warning during LangfuseTracer initialization in case tracing is disabled.

How did you test it?

Tested locally by running the tracer with LangufuseConnector in the following cases:

• importing haystack.Pipeline before setting HAYSTACK_CONTENT_TRACING_ENABLED (warning raised)
• importing haystack.Pipeline after setting HAYSTACK_CONTENT_TRACING_ENABLED (no warning)

Notes for the reviewer

I have not added unit tests because it requires to clear haystack modules and re-import it while having the appropriate HAYSTACK_CONTENT_TRACING_ENABLED env variable set. I though about adding it by removing haystack imports via sys.modules, and re-importing having HAYSTACK_CONTENT_TRACING_ENABLED=false for raising the warning, but apparently by doing so other tests fails, I think I would have to re-import the module while having HAYSTACK_CONTENT_TRACING_ENABLED=true. Let me know if adding a test for it is necessary.

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.

[CLAassistant]

All committers have signed the CLA.

[julian-risch]

@isfuku Thank you for contributing to Haystack! The changes look very good to me. Could you please just add a test before we merge? That test should check if the warning is triggered of we initialize the tracer while the env variable is not set to true. Should be something similar to

import logging

import pytest

...

def test_init_with_tracing_disabled(self, monkeypatch, caplog):
    monkeypatch.setenv("HAYSTACK_CONTENT_TRACING_ENABLED", “false”)
    with caplog.at_level(logging.WARNING):
        assert "tracing is disabled" in caplog.text

in integrations/langfuse/tests/test_tracer.py

[julian-risch]

LGTM! 👍 We could further extend the test with @pytest.mark.parametrize and also check that no warning is emitted if tracing is enabled. And we could create a helper function with the code that clears imported haystack modules so that it can be reused. Still, the code in its current shape is ready to be merged in my opinion.
Thank you and congratulations on your first contribution to Haystack @isfuku !

[julian-risch]

I'll release a new version of the integration tomorrow.