Include source code as asset in releases to avoid issues with GitHub compression algorithm changes

[kjlubick]

The buildifier docs say to create an http_archive using a GitHub source archive URL like https://github.com/bazelbuild/buildtools/archive/refs/tags/4.2.2.tar.gz.

However, as was observed in a large outage on Jan 31, 2023, the compression algorithm used by GitHub can change, breaking sha256 validation.

The recommendation seems to be to include the source zip/tar.gz files in the release itself as an asset (like protobufs does). GitHub promises not to change those bytes since they are user-provided.

Then, the docs should show a URL like:
https://github.com/bazelbuild/buildtools/releases/download/4.2.2/source-4.2.2.tar.gz
depending on what file name for the source code asset is.

[kjlubick]

See also what rules_python did: bazelbuild/rules_python#1032

[luispadron]

Huge +1 here, any plans to do this?