[Maintenance] Run pre-commit in CI and update periodically

[EwoutH]

Currently there is a nice pre-commit configuration, in .pre-commit-config.yaml, but there are two problems:

• It isn't run and enforced in CI, so currently it doesn't do anything.
• The file isn't periodically updated, so most pre-commit actions are over a year old.

Currently running pre-commit.ci results in 123 files changed - all with very minor things like whitespaces/lines and import orders. This why pre-commit only works if it's ran on every commit (in CI).

There are different approaches on this, but by far the most convenient (at least that I know of) is using pre-commit.ci. It takes care of:

• Running pre-commit in CI, and warning if any tests fail
• Updating the pre-commit configuration periodically (daily/weekly/monthly)
• (optionally) directly applying fixes to open PRs (you can enable or disable this)

If this sounds useful, the first step is enabling pre-commit.ci for this repo.

[maartenbreddels]

I'm not sure if I like another service. But I do like running pre commit on everything in CI: #225

That for some reasons failed (my guess was isort+black order / and external/internal library detection).

I wonder if we switch to ruff we can avoid the issue in #225, do you think if that works that #225 is a nice middleground solution?

[EwoutH]

Personally I don't have experience with Ruff yet, but I hear a lot of nice stories about it.

I see that there is a ruff pre-commit hook:

• https://docs.astral.sh/ruff/usage/
• https://github.com/astral-sh/ruff-pre-commit

And it looks like they have proper Black compatibility: https://docs.astral.sh/ruff/formatter/#black-compatibility

So for that part, I think it should work.

But then:

Updating the pre-commit configuration periodically (daily/weekly/monthly)

For this we also need a solution. We could write custom workflow, but that would also need maintenance. Since Dependabot will likely never add support (dependabot/dependabot-core#1524), pre-commit.ci is the only properly maintained solution (I've used it for years in other libraries, its really nice).

[maartenbreddels]

Updating the pre-commit configuration periodically (daily/weekly/monthly)

What is the benefit of that? That you are always up to date with the latest versions of all tools you use?

[EwoutH]

Exactly!

And that you can see if anything breaks if you update to the latest tools (since a PR is opened to update the tools, on which CI is ran).