Angular development now requires a buildifier check: https://github.com/angular/angular/blob/ef534c0cc16b4fd3a4c721f814e5530d63cd6642/.circleci/config.yml#L31
Here are notes from setting this up and the problems we are running into
/cc @mhevery

This doesn't work well for a few reasons:

• developers need to install buildifier on their machines, but it needs to match the version of buildifier run on the CI
• when a change is not formatted, it's hard to both fail the CI, and indicate what changes buildifier expects because --mode=diff exits 0 even if there's a delta, and it doesn't repeat file names
• windows developers don't have the find command indicated here
• developers shouldn't need to think about running buildifier

Here's how I'd like it to work:

• In WORKSPACE add a git_repository pointing here. The tag or commit ensures all developers and CI get the same buildifier version.
• Now I can bazel run @com_github_bazelbuild_buildtools//buildifier but it uses the runfiles directory, it should cd back to the workspace root
• I'd like to have a shorter command for developers, it should be possible to add a simple build rule in my project so I can just bazel run :buildifier (similar to how Gazelle is setup)
• The buildifier rule could also have an implicit output so we could bazel run :buildifier.check on CI
• --mode=diff should exit non-zero if there's a delta, workaround is to run diff followed by check
• --mode=diff needs to echo filenames, otherwise you just get anonymous patches like https://circleci.com/gh/angular/angular/26772
• We should document this setup, along with a git pre-commit hook so all changes to BUILD files get fixed without any effort