Pruning *.dist-info breaks opentelemetry

[maxfriedrich]

Expected Behavior

In a Lambda function with Datadog Lambda layer, from opentelemetry import trace will either work or raise ImportError

Actual Behavior

from opentelemetry import trace raises StopIteration from opentelemetry

Steps to Reproduce the Problem

1. Create Lambda function with Datadog layer >= 95 with this code:

   def lambda_handler(event, context):
       try:
           from opentelemetry import trace
       except ImportError:
           pass

2. Test with any event (no need to configure Datadog credentials)

Specifications

• Datadog Lambda Layer version: broken starting at version 95 (which ships opentelemetry-api 1.25.0, it's not a problem in layer version 94 which ships opentelemetry-api 1.23.0), I also checked layer version 104 which has the same problem
• Python version: 3.11

Stacktrace

[ERROR]	2025-01-05T12:57:30.290Z	76878a64-0217-414a-b18e-3ee9ee8c1275	Failed to load context: ddcontextvars_context, fallback to contextvars_context
Traceback (most recent call last):
  File "./python/lib/python3.11/site-packages/opentelemetry/context/__init__.py", line 45, in _load_runtime_context
StopIteration
[ERROR] StopIteration
Traceback (most recent call last):
  File "/var/task/lambda_function.py", line 12, in lambda_handler
    from opentelemetry import trace
  File "./python/lib/python3.11/site-packages/opentelemetry/trace/__init__.py", line 86, in <module>
  File "./python/lib/python3.11/site-packages/opentelemetry/context/__init__.py", line 69, in <module>
  File "./python/lib/python3.11/site-packages/opentelemetry/context/__init__.py", line 59, in _load_runtime_context

My interpretation

I first saw this error with mysql-connector-python and then isolated it. mysql-connector-python uses a similar try: ... except ImportError to check if opentelemetry is available: https://github.com/mysql/mysql-connector-python/blob/4fbf521f1c6c71621f882f89c0c4946c10ee13ac/mysql-connector-python/lib/mysql/connector/opentelemetry/constants.py#L33-L40

The Datadog Lambda layer ships opentelemetry, so if it's not part of my own zip, any libraries that try to import it use the version from the layer.

opentelemetry-api uses entrypoints to determine the "runtime context": https://github.com/open-telemetry/opentelemetry-python/blob/29aad2efa30a35757ea78d90e4d3fd517bc00468/opentelemetry-api/src/opentelemetry/context/__init__.py#L42-L64

Since the Datadog Lambda layer removes all *.dist-info, this mechanism doesn't work and opentelemetry-api can't find its own fallback context anymore. Also, the Datadog context OTEL_PYTHON_CONTEXT= ddcontextvars_context wouldn't work because the ddtrace .dist-info directory is removed as well.

I think it is reasonable for mysql-connetor-python and other code to assume importing will either work or fail with ImportError and it's also reasonable for opentelemetry-api to assume that its own dist-info is available, so IMO this is a bug in the Datadog Lambda layer. I think either opentelemetry-api should be vendored in some way so other code can't import the incomplete package from opentelemetry or a working version of opentelemetry-api with dist-info should be shipped in the layer.

[purple4reina]

Hey @maxfriedrich, Thanks for reaching out. Yes, you are correct, this is an issue. I'm working now to get the entry_points.txt files re-included in our layers.

[purple4reina]

Hi @maxfriedrich, the fix has been merged and will be included in the next layer release. Thanks again for bringing this to our attention with such a thorough bug report.