Migrate to GitHub Actions.

[jezdez]

Travis CI has a new pricing model which places limits on open source.

• https://blog.travis-ci.com/2020-11-02-travis-ci-new-billing
• https://www.jeffgeerling.com/blog/2020/travis-cis-new-pricing-plan-threw-wrench-my-open-source-works

Many projects are moving to GitHub Actions instead, including Jazzband projects:

• https://github.com/orgs/jazzband/projects/1
• Should we disable travis? jazzband/help#206

This is based on jazzband/contextlib2#26.

TODO:

• @jezdez to add JAZZBAND_RELEASE_KEY to the repo secrets.

[codecov]

Codecov Report

Merging #1410 (b74c95b) into master (dfc863e) will decrease coverage by 0.26%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1410      +/-   ##
==========================================
- Coverage   88.13%   87.86%   -0.27%     
==========================================
  Files          29       29              
  Lines        1576     1574       -2     
  Branches      221      221              
==========================================
- Hits         1389     1383       -6     
- Misses        139      141       +2     
- Partials       48       50       +2     

Impacted Files	Coverage Δ
debug_toolbar/panels/cache.py	83.58% <ø> (ø)
debug_toolbar/panels/history/panel.py	95.55% <100.00%> (-0.19%)	⬇️
debug_toolbar/panels/settings.py	87.50% <0.00%> (-12.50%)	⬇️
debug_toolbar/panels/sql/tracking.py	87.71% <0.00%> (-1.76%)	⬇️

---

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[jezdez]

So this is a bit more complicated GHA config since it tests three databases and has extra test environments to do linting, and a single environment to do Selenium testing (which is installde by default).

I'm a bit worried that this takes way too long for each Python version, but I couldn't figure out how to do this better (e.g. using more dimensions like database engine).

If any of the reviewers have an idea how to improve this, I'd appreciate it! Thank you :)

[hugovk]

One idea is to factor things back out to the matrix. The earlier Travis config had more or less one job per Python x Django version. Maybe do that here, or for the database engines.

Have a look at this example, you can see an OS x Python matrix:

https://github.com/hugovk/pypistats/blob/7033d0adff90726f439b1b804485fac3fe92c6ec/.github/workflows/test.yml#L10-L12

You can also use include: to things not generated by the matrix. For example, something like this should give us 4x3 jobs (4 Python x 3 OS) + 1 extra (3.5 on Ubuntu):

      matrix:
        python-version: [3.6, 3.7, 3.8, 3.9]
        os: [ubuntu-latest, macos-latest, windows-latest]
        include:
          - { python-version: 3.5, os: ubuntu-latest }

(The includes in https://github.com/hugovk/pypistats/blob/7033d0adff90726f439b1b804485fac3fe92c6ec/.github/workflows/test.yml#L13-L18 are a bit different: because the OS matches something in the matrix, it adds a new variable for those.)

Similarly, it's possible to exclude things. This should give us 4x3 - 1 (skip 3.6 on macOS):

      matrix:
        python-version: [3.6, 3.7, 3.8, 3.9]
        os: [ubuntu-latest, macos-latest, windows-latest]
        exclude:
          - { python-version: 3.6, os: ubuntu-macos-latest }

Here's an exclusion example: https://github.com/hugovk/tinytext/blob/f1553124d2ab476e9d096ff521a61c9d57587d86/.github/workflows/test.yml#L22-L24

Would something like this help?

[jezdez]

@hugovk I've stolen some of techniques for this from @laymonage's django-jsonfield-backport and I think just specifying multiple jobs is the only way to cater to the mix of GHA-level factors and tox-level factors. Or at least I wasn't able to make this happen using tox-gh-actions. I can live with the slight code duplication. WDYT?

[hugovk]

I think this is good, especially to get the migration done, and it can always be iterated on later.

[jezdez]

Thanks, agreed! 😌

[matthiask]

Thanks, this is awesome!