GH-102973: add a dev container

[brettcannon]

Defines a Dockerfile based on Fedora along with common tooling (e.g. various shells people may want to use). It also includes the tooling necessary to do a cross-build for WASI.

Co-authored-by: Dusty Phillips dusty@phillips.codes

• Issue: Add a dev container to the repository #102973

[encukou]

@frenzymadness, do you want to take a look?

(I wont't get to it this week)

[frenzymadness]

Thanks @encukou for the ping. I like it. You might want to use --setopt=tsflags=nodocs for the dnf command to skip documentation packages (--no-docs should work as well) and then you might want to do dnf -y clean all to remove cached files from the resulting image.

[brettcannon]

Thanks @frenzymadness ! PTAL and let me know if I got everything you were suggesting.

[frenzymadness]

Thanks @frenzymadness ! PTAL and let me know if I got everything you were suggesting.

Looks perfect to me now.

[encukou]

I'm not familiar with devcontainers, let me throw ideas around for consideration.

I don't understand the onCreateCommand. Is in any different from the Dockerfile install section? Installing everything at once could save some repo syncing.

You might want to install ccache to speed up builds, especially after switching branches. The default cache size (5G, AFAIK) might be too much.

You might want to install python3-blurb from RPM, if avoiding yet another tool (pipx) sounds interesting.

There's also a python3-sphinx RPM. With it you could make --directory Doc html without venv to save time. If you want to add it, install with dnf --setopt=install_weak_deps=False to skip dependencies related to image manipulation.

[brettcannon]

I don't understand the onCreateCommand. Is in any different from the Dockerfile install section? Installing everything at once could save some repo syncing.

It is, but I view the dev container details as specific to editing via GitHub Codespaces while with the Dockerfile I tried to take a less opinionated approach.

You might want to install ccache to speed up builds, especially after switching branches. The default cache size (5G, AFAIK) might be too much.

👍

You might want to install python3-blurb from RPM, if avoiding yet another tool (pipx) sounds interesting.

I'm up for it!

There's also a python3-sphinx RPM. With it you could make --directory Doc html without venv to save time.

With GitHub Codespaces prebuilds the save is minimal since the assumption is everyone will start from the container already created and all of those commands already run (takes less then 45 seconds to get to a terminal prompt). But I'm up for trying it out!

[brettcannon]

Turns out python3-sphinx is the wrong Sphinx version and skips installing the theme and other things required to build the docs, so I don't think it's going to improve anything.

[brettcannon]

I decided to not go with ccache to start since it could lead to actual costs for people who might not be aware that ccache is running and upping the amount of storage their Codespace is using while not being required to simply build Python effectively (granted, people get 15GB free every month and USD $0.07/GB after that, but still).

[brettcannon]

I decided to go ahead and merge this as we can easily update it if there's anything we want to tweak.

[methane]

It takes 20min to start Codespace.
Could you enable prebuild in this repository?

[brettcannon]

It takes 20min to start Codespace. Could you enable prebuild in this repository?

Already working on it; have to get budget from the PSF first.

[encukou]

In case you want to revisit ccache (e.g. if juggling branches is a common use case), the cache size can be set with echo 'max_size = 100M' > /etc/ccache.conf

• I'm assuming the devcontainer script controls system-wide setup (/etc/): user-specific config should go to $HOME/.config/ccache/ccache.conf & Fedora defaults are compiled in
• A full build takes up ~27M of cache, two very different branches (3.12 and 3.6) fill ~40M.

Turns out python3-sphinx is the wrong Sphinx version and skips installing the theme and other things required to build the docs, so I don't think it's going to improve anything.

Fair. I use it (one less venv → one less update command to forget to run, and with docs previews a slightly outdated version doesn't matter that much), but, it's not for everyone.
But in case it's useful: to install the theme, linkchecker, and other things, there's dnf builddep python3-docs

[brettcannon]

In case you want to revisit ccache (e.g. if juggling branches is a common use case), the cache size can be set with echo 'max_size = 100M' > /etc/ccache.conf

Yep, I believe you can also use ccache --max-size, but since that decision could cost people money, I didn't want to make that decision for them.

(one less venv → one less update command to forget to run, and with docs previews a slightly outdated version doesn't matter that much

True, although once we get prebuilds up and running that will be automatic after every commit to main.

[brettcannon]

Prebuilds have been turned on! https://github.com/python/cpython/actions/workflows/codespaces/create_codespaces_prebuilds

/cc @methane

[hroncok]

I realize I am late to the party, but you might save space by installing git-core instead of git, which should avoid Perl (unless something else brings it in).
(dnf builddep python3 will bring in git-core as well, because we use git to apply patches, but that is probably not explicit enough.)

[hroncok]

Invoking dnf with --setopt=install_weak_deps=False will also save space. Let me try sending a PR and see if it works.

[hroncok]

#103283