Thanks for your feedback, and for taking the trouble to leave your comments. The documentation is generated automatically from the contents of this forum, where anyone can edit, so the docs are the result of a snap-team/community effort.
I can totally see what you mean here. I’ll reword this, and elsewhere where this paragraph is used, to make it more explicit. It should also link to our Base snap documentation, and we really should go through these tutorials to help make them easier to understand and more consistent with some of the snap/snapcraft changes that have been implemented since they were written.
Just noticed that the snapcraft.yaml file presented here does not exactly match what is grabbed from the git repo for this example. In the repo, confinement is “strict”, and the override-pull scriptlet does a “set-version” as well. Someone should make sure this page is sync’ed with that is in the repo.
Hi, I’m having some trouble with snapping my python CLI tool.
Reading on the requirements: “It will automatically include these in your snap.” I understand that the python plugin will grab the requirements.txt from my project and automatically include them in the snap.
However, if I go and check the archive’s site-packages, they are not there (and an ImportError confirms that).
I had to include them via python-packages for it to work.
Thanks for bringing this to our attention! Our instructions above are out of date - you now need to manually add requirements: requirements.txt to point at the location of the requirements file. I’ll give this a quick test and update the document.
The official Python example in " Getting started" doesn’t build on a fresh ubuntu 22.04 machine, leading to the error:
+ snapcraftctl stage
+ snapcraftctl prime
Determining the version from the project repo (version: git).
fatal: not a git repository (or any of the parent directories): .git
Run the same command again with --debug to shell into the environment if you wish to introspect this failure.
version: git really only works if your snapcraft.yaml is in the source tree you’re building…
so why does the official python example use this syntax? The repository https://github.com/yt-dlp/yt-dlp doesn’t contain a snapcraft.yaml. The workaround suggested by popey did work which means arguably the official example should be changed to be:
summary: A fork of youtube-dl with additional features and patches
Download and play videos on your local system. Runs from the command
line and with all the features and patches of youtube-dlc in addition
to the latest youtube-dl.
- build-on: [arm64, armhf, amd64]
plugs: [home, network, network-bind, removable-media]
# https://forum.snapcraft.io/t/git-error-while-building-snap/10130 advice
snapcraftctl set-version $(git describe --tags)
where I replaced version: git with adopt-info: yt-dlp and added the override-build lines.
Some misc thoughts with the documentation page on Python apps:
The need for there to be a setup.py for Python apps to build under the snapcraft Python plugin intoduces a steep hurdle to adoption IMO.
The inability to use different Python versions, other than what is supplied by default in the base is disappointing and has been a limitation for many years, with developers struggling with workarounds e.g. Build a snap with any version of Python I want
Building the snap example using snapcraft --use-lxd on a fresh install of ubuntu 22.04 server (then upgraded to add desktop) fails. You have to sudo lxd init --auto to get lxd to work properly - worth mentioning somewhere in the doco, even if its not a specifically python issue.
Summary of my experience:
snapcraft with lxd tooling initially failed, had to google workaround
official yt-dlp Python example failed to build, had to google workaround
can’t begin to package my python project without modifying it and learning about setup.py - it would be nice to be able to create a snap for a normal unpackaged Python program, which 99% of python apps are.
can’t use a version of Python that I want - stuck with what is supplied in corexx
the need to specify additional unknown linux packages in a stage-packages: and build-packages: sections e.g. libssl-dev libjpeg-dev libtiff-dev libgtk2.0-0 etc. etc. is a huge blocker. Even when snapcraft reports library names are needed, those names are not usable and one must apt-file search xxx each one to get a name acceptable to snapcraft.
The gnome extension does not play well with the python plugin and snaps cannot get into the snapstore see Core22 gnome extension and broken symlinks without manually editing the snap and removing certain files.
Thanks for your detailed feedback. I think you’re right about a lot of these Getting started pages - I/we should create a task to go through them all. There’s a lot of duplication, some of the details are no longer relevant, and the examples might not always be the best choices. I think it’s important we address these issues as soon as we can. I will go through this one with some urgency though as you raise some good points.
Although not important for your points, the actual example in the Build the snap section clones a fork of the upstream project with a working git version reference (git clone https://github.com/degville/snap-yt-dlp.git), but this isn’t clear in the earlier yaml snippet. This fork also builds for me and contains only two staged packages. If you don’t have LXD installed, snapcraft should prompt for this and install it when it’s first run (I’ve just tried this on a fresh 22.04 and the prompt worked for me).
Thanks again for your feedback. I’ll make sure we update these docs.
This is a good idea, and something we’re aware of. It’s not been done because we should also be using a completely different example snap (for obvious reasons - incidentally, the snap itself is already using core22 if you follow the link). I’ll put some effort into finding or creating one and update this doc. I’ll also make it a priority because Python is important.
Edit: 7th September 2023 This work has now been done. A better example Python project as chosen, now using core22, with updated and more concise yaml.