Error running locally built image with pack: Fatal Python error: init_fs_encoding: failed to get the Python codec of the filesystem encoding about buildpacks-python

[edmorley]

@david-caro Thank you for the great bug report + testcase, that helped a lot with my being able to reproduce.

This looks like a potential bug in uWSGI (or at least a limitation of it), since it's not honouring Python's detection of stdlib location, and instead is using the original build time location of Python, before it was relocated. For example, if you run docker run --rm -it --entrypoint launcher wm-lol python -m sysconfig, you will see that the "Paths:" section right at the top has all the correct locations.

I'm planning on reporting this upstream to uWSGI, as well as having the Python CNB set PYTHONHOME as a workaround in the meantime (which may end up needing to be set long term, given there will be apps in the wild using old uWSGI versions that never get the fix, even if uWSGI do fix this).

[edmorley]

I've reported this upstream to the uWSGI project here:
unbit/uwsgi#2525

[ipmb]

This is more of a workaround than a fix, but I'm curious if using https://pypi.org/project/pyuwsgi/ resolves the issue.

[edmorley]

I just noticed the GCP Python CNB sets PYTHONHOME because of uWSGI too:
https://github.com/GoogleCloudPlatform/buildpacks/blob/99553d0a2051834324d621f20ad5355453f675a1/cmd/python/runtime/main.go#L93-L96