tox -e update_docker_platforms

[mkoeppe]

Furthering my hidden agenda of bringing portability tools to the masses.

• We add .devcontainer/portability-*/devcontainer.json files for all platforms tested in our CI. This makes them selectable in GitHub Codespaces.
• The files are generated by the new command tox -e update_docker_platforms, which also updates the workflow file .github/workflows/docker.yml.
• The command also adds a table to the portability testing section in the developer's guide with links to GitHub Packages and friendly "Run in GitHub Codespaces" buttons.
• Because 'tis the season of Spielzeugneid, we document how to run the portability testing in GitHub Codespaces via Docker-in-Docker, useful for those who cannot run Docker on their own computers. This uses a new devcontainer config "tox-docker-in-docker".
• We make various other updates to the portability testing section in the developer's guide.

📝 Checklist

• The title is concise, informative, and self-explanatory.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation accordingly.

⌛ Dependencies

• Depends on Small update to Developer Guide section on portability testing #37030 (split out from here)

[kwankyu]

This looks better

.. list-table::
   :width: 200
   :widths: 50 20 50 50
   :header-rows: 1
   :stub-columns: 0

   * - Platform
     - System packages
     - Images
     -
   * - **ubuntu**-trusty-toolchain-gcc_9
     - minimal
     - |image-ubuntu-trusty-toolchain-gcc_9-minimal-with-system-packages| |image-ubuntu-trusty-toolchain-gcc_9-minimal-with-targets-pre| |image-ubuntu-trusty-toolchain-gcc_9-minimal-with-targets| |image-ubuntu-trusty-toolchain-gcc_9-minimal-with-targets-optional|
     - |codespace-ubuntu-trusty-toolchain-gcc_9-minimal|
   * -
     - standard
     - |image-ubuntu-trusty-toolchain-gcc_9-standard-with-system-packages| |image-ubuntu-trusty-toolchain-gcc_9-standard-with-targets-pre| |image-ubuntu-trusty-toolchain-gcc_9-standard-with-targets| |image-ubuntu-trusty-toolchain-gcc_9-standard-with-targets-optional|
     - |codespace-ubuntu-trusty-toolchain-gcc_9-standard|
   * -
     - maximal
     - |image-ubuntu-trusty-toolchain-gcc_9-maximal-with-system-packages| |image-ubuntu-trusty-toolchain-gcc_9-maximal-with-targets-pre|
     -  

[tobiasdiez]

Please don't commit the auto-generated devcontainer files. The would show up at https://github.com/codespaces/new?hide_repo_select=true&ref=develop&repo=597660615&skip_quickstart=true, and a drop down box should not contain more than 10-20 options to be useful. Also, if I'm not mistaken, the docs already explain how to start a devcontainer for the portability tests.

[kwankyu]

Please don't commit the auto-generated devcontainer files. The would show up at https://github.com/codespaces/new?hide_repo_select=true&ref=develop&repo=597660615&skip_quickstart=true, and a drop down box should not contain more than 10-20 options to be useful.

I experimented on it. The dev container files appear sorted alphabetically by their filenames, and the new dev container files (that start with "portability-") appear to the bottom of the dropdown box. Hence there is no inconvenience incurred by this PR. The conda dev container (perhaps your favorite) is still placed at the top.

[tobiasdiez]

Thanks for testing, but I was already aware of the sorting and took this into account.

I would be fine with adding a few common configs, but not almost hundred.

[mkoeppe]

the docs already explain how to start a devcontainer for the portability tests.

That's right. This PR lowers the barrier further -- in particular by making these options available in the devcontainer dropdown menu on PRs.

I would be fine with adding a few common configs

There's no such thing, as I explained in detail in #36726.

[mkoeppe]

This looks better

.. list-table::
   :width: 200
   :widths: 50 20 50 50
   :header-rows: 1
   :stub-columns: 0

Not sure about this. Have you tried this in a narrow window?

[kwankyu]

Not sure about this. Have you tried this in a narrow window?

I just did. In the narrowest window (perhaps corresponding to the vertical mode of hand-held devices), the PR version looks okay. In this case, the font is too small in my version. Except this extreme case, my version shows always the four images stacked nicely and codespaces button separately on the right, which look tidy overall (even in the extreme case).

[kwankyu]

Instead of tox -e update_docker_platforms, how about

tox -e update_devcontainer_files

as this is what is done? Just a mild suggestion.

[github-actions]

Documentation preview for this PR (built with commit aa7dab3; changes) is ready! 🎉

[kwankyu]

Enough lingering here.

[mkoeppe]

Thanks!