Add Python version datasource

[not7cd]

Tell us more.

Just like for Node releases, Renovate should be able to propose update to Python version. I want Renovate to bump deprecated Python versions that are hardcoded as variable in Dockerfiles. This can be done with custom managers, but a release data source is needed first.

Python.org offers an API with all releases: https://www.python.org/api/v2/downloads/release/

While release status is found here: https://github.com/python/devguide/blob/main/include/release-cycle.json

[jamietanna]

We should hopefully be able to wire https://docs.renovatebot.com/modules/datasource/endoflife-date/ in with this to source deprecation / EOL dates

[rarkins]

It's important that the source chosen is also representative of whether it can be installed. In this case it's essential that it does not "precede" Renovate's ability to install python using install-tool, otherwise you'll get a PR updating python with an artifacts error because the new Python error wasn't installable. That source is here: https://github.com/containerbase/base/blob/main/src/usr/local/containerbase/utils/python.sh

@viceice is it using virtualenv to install python versions?

[not7cd]

pyenv support is updated manually. pyenv/pyenv#2899
This may be interpreted as an index
https://github.com/pyenv/pyenv/tree/master/plugins/python-build/share/python-build

[not7cd]

This has already bitten someone in kachick/renovate-config-asdf#1568 using asdf manager

[viceice]

I've already a hack to try to build a new python patch from previous version when pyenv isn't updated.

but that doesn't work for minors

[rarkins]

Wondering:

• Is there an alternative to pyenv to allow faster builds of new releases?
• Is pyenv holding back the prereleases or is that our own policy in containerbase?

[not7cd]

I would opt for slower containerbase/python-prebuild dependent release. Because this is the final bottleneck. This Datasource will benefit from any optimizations to it.

[not7cd]

I have created a PR that attempts to implement this data source based on node-version
#27583

[not7cd]

This PR is ready. To no surprise, I'm now in the process of getting rid of deprecated Python versions. And I'm going to test it in "production" in the next week.