python:3.8 does not include /usr/lib/python3/dist-packages in sys.path

[MarcelWaldvogel]

The following Dockerfile fails with ModuleNotFoundError:

FROM python:3.8
RUN apt update && apt install python3-urllib3
RUN python3 -c "import urllib3"

Adding ENV PYTHONPATH=/usr/lib/python3/dist-packages before the python3 command will make it run smoothly. So it ignores libraries installed by apt, which is e.g. essential for pygit2, which cannot be reasonable installed with pip/pip3.

[wglambert]

#43 (comment)

I'm not sure I'm following for what's gained by supporting this path besides encouraging people to mix Debian Python packages with pip install packages? (which is generally considered harmful)

I think if you're relying on Debian-packaged python dependencies, you're probably going to be better off going straight for either FROM debian or FROM buildpack-deps instead of trying to get this image to do what you might expect when mixing dependencies from APT and elsewhere.

https://packages.debian.org/buster/python3-urllib3
Python3 is a dependency, which will install Python from the Debian repo's alongside the image's compiled Python

[tianon]

Closing as duplicate of #43

[MarcelWaldvogel]

On ARM, pip3 install pygit2 fails at compile-time, as it is missing git2.h. Trying to first apt update && apt install libgit2-dev fails, because, again at compile-time, a version mismatch between libgit2-dev (0.27.4) and pygit2 (1.2.1) is detected. Including rules for selecting the appropriate pygit2 version is horrible, so requiring pygit2 along with other packages from pypi essentially requires mixing native packages and python packages.

But I might consider switching to FROM debian, even though multiarch building will be much slower then.