Wire up composite sampler

[anuraaga]

What does this pull request do?

This wires up the new composite sampler to EDOT.

I followed the same approach as EDOT Java which enables the sampler unconditionally I believe

https://github.com/elastic/elastic-otel-java/blob/1254b84e16c5cf6829f2b84bf63c902b71626448/custom/src/main/java/co/elastic/otel/ElasticAutoConfigurationCustomizerProvider.java#L95

Happy to change to registering a OTEL_TRACES_SAMPLER name instead, presumably the behavior should be consistent between the two though - I can update Java if we change it.

/cc @xrmx @AlexanderWert @jackshirazi

[xrmx]

Suggested change

# FIXME: this needs to be updated for the consistent probability samplers

[xrmx]

We should also remove these from the documentation. Need to check priority of OTEL_TRACES_SAMPLER env var against the configure parameter. An option is to provide our own entry points and just switch to it there?

[jackshirazi]

I followed the same approach as EDOT Java which enables the sampler unconditionally I believe

I consider EDOT to provide an opinionated agent. If customers need better configurability, let them feed that back rather than we try an anticipate needs that might not be requested

[anuraaga]

Thanks @xrmx - I have updated to take the approach from the EDOT proposal, now we define an entry point and set it as default but don't force the sampler otherwise. /cc @trentm

[anuraaga]

@xrmx based on the test logging, it looks like there was already an issue with loading entry points, not just my new one. I guess it's a test infrastructure issue, can you help with it? Note that I run locally using uv run pytest and it works fine, so maybe pip specific.

WARNING  opentelemetry.sdk._configuration:__init__.py:390 Using default sampler. Failed to initialize sampler, experimental_composite_parentbased_traceidratio: Requested component 'experimental_composite_parentbased_traceidratio' not found in entry point 'opentelemetry_traces_sampler'
ERROR    opentelemetry.sdk.resources:__init__.py:224 Failed to load resource detector 'service_instance', skipping
Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.11.13/x64/lib/python3.11/site-packages/opentelemetry/sdk/resources/__init__.py", line 214, in create
    next(
StopIteration
ERROR    opentelemetry.sdk.resources:__init__.py:224 Failed to load resource detector '_gcp', skipping
Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.11.13/x64/lib/python3.11/site-packages/opentelemetry/sdk/resources/__init__.py", line 214, in create
    next(
StopIteration
ERROR    opentelemetry.sdk.resources:__init__.py:224 Failed to load resource detector 'process_runtime', skipping
Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.11.13/x64/lib/python3.11/site-packages/opentelemetry/sdk/resources/__init__.py", line 214, in create
    next(
StopIteration

[xrmx]

@xrmx based on the test logging, it looks like there was already an issue with loading entry points, not just my new one. I guess it's a test infrastructure issue, can you help with it? Note that I run locally using uv run pytest and it works fine, so maybe pip specific.

WARNING  opentelemetry.sdk._configuration:__init__.py:390 Using default sampler. Failed to initialize sampler, experimental_composite_parentbased_traceidratio: Requested component 'experimental_composite_parentbased_traceidratio' not found in entry point 'opentelemetry_traces_sampler'
ERROR    opentelemetry.sdk.resources:__init__.py:224 Failed to load resource detector 'service_instance', skipping
Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.11.13/x64/lib/python3.11/site-packages/opentelemetry/sdk/resources/__init__.py", line 214, in create
    next(
StopIteration
ERROR    opentelemetry.sdk.resources:__init__.py:224 Failed to load resource detector '_gcp', skipping
Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.11.13/x64/lib/python3.11/site-packages/opentelemetry/sdk/resources/__init__.py", line 214, in create
    next(
StopIteration
ERROR    opentelemetry.sdk.resources:__init__.py:224 Failed to load resource detector 'process_runtime', skipping
Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.11.13/x64/lib/python3.11/site-packages/opentelemetry/sdk/resources/__init__.py", line 214, in create
    next(
StopIteration

I think I've seen that upstream too when running sdk tests yesterday, I'll take a look.

[xrmx]

I think the issue is quite simple, if the package is not installed its entry points are not visible :) So to solve this we can mock the configurator code that loads the sampler entry points or introduce something like nox.

noxfile.py:

import nox

@nox.session
def tests(session):
    session.install('-r', 'dev-requirements.txt')
    session.install('pytest-vcr')
    # this is what make the thing work
    session.install('-e' '.')
    session.run('pytest')

Install nox and run nox

[xrmx]

@anuraaga I'm going to setup nox so you can rebase on top

[anuraaga]

Makes sense. uv also automatically installs the package before uv run so wiring it into CI could be an option too.

[xrmx]

Here's the PR for setting up nox: #415