python bindings when building from scratch

[pbaetens]

Hi all,

situation:

I build latest libcam and rpicam-apps from scratch.
commands like rpicam-hello work fine.
However, the python binding is not working.

python -m venv --system-site-packages venv
source venv/bin/activate
python
>>> import libcamera
>>> ModuleNotFoundError

Solution:
create a symbolic link to a place where python can find the .so file
sudo ln -sf /usr/local/lib/aarch64-linux-gnu/python3.11/site-packages/libcamera /usr/local/lib/python3.11/dist-packages/libcamera

OS: Bookworm

Question:
is this the way to do it, or is there a better way?

[naushir]

@pbaetens thanks for the info. I must admit, python and venv is not something I am very familiar with, so I cannot say if there is a better way than what you described.

@davidplowman @XECDesign is this a solution to the venv issue we were talking about last week?

[pbaetens]

seems related to:
https://patchwork.libcamera.org/patch/19186/
So there is a patch in upstream libcamera but not yet merged.
@kbingham @will-v-pi

[kbingham]

I've hit this a few times and I just set the python path which is another "work around". But I would love to see this resolved more globally too.

@will-v-pi there are comments from Tomi for you. Do you have time to reply to the patch please?

[will-v-pi]

@kbingham I think the decision on that patch was not to merge it, as the behaviour that I was looking for wasn't cleanly compatible with cross-compilation? The patch was getting a bit complicated, and wasn't actually required for my rpi-libcamera pip package to compile. Tomi also mentioned that it would still install to an incorrect path on his PC, as that patch would install everything to site-packages whereas his PC only searched for dist-packages, so it's possibly not the correct solution to this problem?

I have a small downstream patch in raspberrypi/pylibcamera which I'm using to build the rpi-libcamera pip package, but that's specifically for building just the python bindings within that repository, rather than the whole of libcamera.

[naushir]

From the above comments, I don't think there's anything we are able to do here...