keylog_filename triggering error when SSLKEYLOGFILE is not set

[mattbasta]

Subject

Requests are failing with the error:

urllib3.exceptions.ProtocolError: ('Connection aborted.', FileNotFoundError(2, 'No such file or directory'))

The line that raises this exception is the following (at the bottom of the stacktrace):

File "/Users/basta/.local/share/virtualenvs/venv-OmZ6DiXY/lib/python3.8/site-packages/urllib3/util/ssl_.py", line 302, in create_urllib3_context
    context.keylog_filename = os.environ.get("SSLKEYLOGFILE")

Editing this file to print os.environ.get("SSLKEYLOGFILE") shows that this is empty.

This issue started happening after upgrading from Python 3.7 to 3.8.

Environment

This issue is happening for me on macOS Catalina 10.15.2.

import platform
import urllib3

print("OS", platform.platform())
print("Python", platform.python_version())
print("urllib3", urllib3.__version__)

returns

>>> import platform
>>> import urllib3
>>>
>>> print("OS", platform.platform())
OS macOS-10.15.2-x86_64-i386-64bit
>>> print("Python", platform.python_version())
Python 3.8.5
>>> print("urllib3", urllib3.__version__)
urllib3 1.25.10

Steps to Reproduce

This issue is always reproducible when making any requests using the stripe-python library. I don't have access to other machines to try to reproduce it elsewhere. However, it does not occur in my production environment (Linux) on the same Python version (3.8).

Expected Behavior

I would expect this line to no-op rather than raising. Replacing if hasattr(context, "keylog_filename"): with if hasattr(context, "keylog_filename") and os.environ.get("SSLKEYLOGFILE"): in ssl_.py eliminates the issue.

Actual Behavior

The noted exception is raised.

[sethmlarson]

Thanks for opening this, this looks like a bug. We'll get a fix in and make a 1.25.11 release.

Would you be willing to provide a patch and test case? If not no problem.

[mattbasta]

@sethmlarson I'm happy to put up my little patch as a PR. I'm not so sure how to test it, though, since the problem only seems to occur on my one machine running macOS (and I can't possibly be the only person using Stripe's SDK on python 3.8!).

If the fix alone is enough, I can have that up soon. You're welcome to use it as a guide or take it over or whatever.

[mattbasta]

Awesome, thanks for the fast fix! This is much appreciated.