Comment by gjvc
3 years ago
Yes 1000x What is it with them which makes them feel entitled to have special "dist-packages" vs "site-packages" as is the default? This drives me nuts, when I have a bunch of native packages I want to bundle in our in-house python deployment. CentOS and Ubuntu are vanilla, and only Debian (mind-boggingly) deviates from the well-trodden path.
I still haven't figured out how to beat this dragon. All suggestions welcome!
> What is it with them which makes them feel entitled to have special "dist-packages" vs "site-packages" as is the default? This drives me nuts, when I have a bunch of native packages I want to bundle in our in-house python deployment. CentOS and Ubuntu are vanilla, and only Debian (mind-boggingly) deviates from the well-trodden path.
Hi, I'm one of the people that look after this bit of Debian (and it's exactly the same in Ubuntu, FWIW).
It's like that to solve a problem (of course, everything has a reason). The idea is that Debian provides a Python that's deeply integrated into Debian packages. But if you want to build your own Python from source, you can. What you build will use site-packages, so it won't have any overlap with Debian's Python.
Unfortunately, while this approach was designed to be something all package-managed distributions could do, nobody else has adopted it, and consequently the code to make it work has never been pushed upstream. So, it's left as a Debian/Ubuntu oddity that confuses people. Sorry about that.
My recommendations are: 1. If you want more control over your Python than you get from Debian's package-managed python, build your own from source (or use a docker image that does that). 2. Deploy your apps with virtualenvs or system-level containers per app.
Dist packages is the right way to handle Python libs. You'd prefer to have the distro package manager clashing with Pip? Never knowing who installed what. Breaking things when updates are made.
I usually make a venv in ~/.venv and then activate it at the top of any python project. Makes it much easier to deal with dependencies when they're all in one place.
i am a big fan of .venv/ -- except when it takes ~45 mins to compile the native extension code in question -- then I want it all pre-packaged.
At this stage [0], uncompiled native extensions are not yet a bug, but a definite oversight of the maintainer. They should come as precompiled wheels
[0]: https://pythonwheels.com
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It's a good idea to be caching sdists and wheels — for resilience against PyPI downtime, for left-pad scenarios, and even just good netiquette — and for packages that don't have a wheel for your environment, you can fairly easily build that wheel yourself and stick it into the cache.
second this and it's what I do on all Linux distros, just run it inside .venv as the site-installation.
if you need extra dependencies that pip can not do well in the .venv case, Conda can help with its own and similar site-based installation.
I don't know how it is different in the python installation case between ubuntu and debian, they seem the same to me.
IMO bespoke containers using whatever python package manager makes sense for each project. Or make the leap to Nix(OS) and then still have to force every python project into compliance which can be very easy if the PyPy packages you need are already in the main Nix repo (nixpkgs) or very difficult if depends on a lot of uncommon packages, uses poetry, etc.
Since PEP 665 was rejected the Python ecosystem continues to lack a reasonable package manager and the lack of hashed based lock files prevents building on top of the current python project/package managers.
dist packages are a must for software written in Python that is part of the distribution itself.
You're not really answering why they are important?
Is it because .deb packages will install inside dist-packages and when you run pip install as root without a virtual env, it installs inside site-packages?
I don't really see how this helps though? Sure you won't get paths to clash between the two but you still have duplicate packages which is probably not what you want..
Debian ships packages with a coherent dependency structure that crosses language boundaries. You don't need to care what language something is written in to be able to "apt install" it. The expectation is that if it "apt installed" then it should Just Work because all the required dependencies were also pulled in from Debian at the same time.
Debian also tries to ship just one version of everything in a single distribution release to reduce the burden on its maintainers.
This is fundamentally at odds with pip. If you've pip installed something, then that'll likely be the latest version of that package, and in the general case won't be the version of the same thing that shipped in the Debian release. If there exist debs that depend on that package and they are shared between pip and debs, now the deb could be using a different version of the dependency than the deb metadata says is acceptable, leading to breakage.
Another way of putting this: it shouldn't be possible for you to pip upgrade a dependency that a deb shipped by Debian itself relies upon. Because then you'd creating a Frankenstein system where Debian cannot rely on its own dependencies providing what it expects.
This is fixed by having two places where things are installed. One for what the system package manager ships, and one for your own use with pip and whatever you want to do. In this sense, having duplicate packages is actually exactly what you want.
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Imagine you installed python3-requests (version x.y.z). Some of your distribution's packages depend on that specific package/version.
If you pip install requests globally, you just broke a few of your distrib's packages.
> I still haven't figured out how to beat this dragon. All suggestions welcome!
Docker