2022-12-09
Sometimes an Ubuntu package of a Python module is probably good enough
Recently I ran across a Python program we're interested in, and discovered that it required prometheus-client. Normally this would mean creating a virtual environment and installing the module into it, possibly along with the program (although you don't have to put the program inside the venv it uses). But when I looked out of curiosity, I saw that Ubuntu packages this module, which got me to thinking.
I'm generally a sceptic of relying on the Ubuntu packaged version of a Python module (or any OS's packaged version); I wrote about this years ago in the context of Django. Linux distribution packaging of Python modules is famously out of date, and Ubuntu makes it worse by barely fixing bugs at the best of times. However, this feels like a somewhat different situation. The program isn't doing anything much with the prometheus-client module, and the module itself isn't very demanding; probably quite a lot of versions will do, and there's unlikely to be a bug that affects us. Indeed, some quick testing of the program with the Ubuntu version suggests that it works fine.
(Although now that I look, the Ubuntu version is rather out of date. Ubuntu 22.04 LTS packages 0.9.0, from 2020-11-26, and right now according to the module's releases page it's up to 0.15.0, with quite a few changes.)
Provided that Ubuntu's version of the module works, which it seems to, using the Ubuntu packaged version is the easy path. It's not an ideal situation, but for something with simple needs (and which isn't a high priority), it's rather tempting to say that it's okay. And if the Ubuntu version proves unsatisfactory, changing over to the latest version in a virtual environment is (at one level) only a matter of changing the path to Python 3 in the program's '#!' line.
(We have another program that requires a Python module, pyserial, that we get from Ubuntu, but I didn't think about it much at the time. This time around I first built a scratch venv for the program to test it, then discovered the Ubuntu package.)
2022-12-08
Python version upgrades and deprecations
Recently I read Itamar Turner-Trauring's It’s time to stop using
Python 3.7
(via). On the
one hand, this is pragmatic advice, because as the article mentions
Python 3.7 is reaching its end of life as of June 2023. On the other
hand it gives me feelings, and one of the feelings is that the
Python developers are not making upgrades any easier by slowly
deprecating various standard library modules. Some of these modules
are basically obsolete now, but some are not and have no straightforward
replacement, such as the cgi module.
The Python developers can do whatever they want to do (that's the power of open source), and they clearly want to move Python forward (as they see it) by cleaning up the standard library. But this means that they are perfectly willing to break backward compatibility in Python 3, at least for the standard library.
One of the things that make upgrading versions of anything easy is if the new version is a drop in replacement for the old one. Deprecating and eventually removing things in new versions means that new versions are not drop in replacements, which means that it makes upgrading harder. When upgrading is harder, (more) people put it off or don't do it. This happens regardless of what the software authors like or think, because people are people.
I doubt this is a direct factor in people still using Python 3.7. But I can't help but think that the Python developers' general attitude toward backward compatibility doesn't help.
(Python virtual environments make different versions of Python not exactly a drop in replacement; in practice you're going to want to rebuild the venv. But my impression is that pretty much everyone who is seriously using Python with venvs has the tools and experience to do that relatively easily, because their venvs are automatically built from specifications. Someday I need to master doing that myself, because sooner or later we're going to need to use venvs and be able to migrate between Python versions as part of an OS upgrade.)