In the Bazel world, we don’t always want it to track all the files in our repository. A typical example is ignoring the .git directory, as it can grow quite large over time. Additionally, some IDE integrations like rules_xcodeproj don’t work particularly well when it is present.

Traditionally, to instruct Bazel to ignore directories and files, we used the .bazelignore file, which requires explicitly listing paths to ignore. This works, but it has an important limitation: .bazelignore does not support glob patterns. As a result, we often need to update the file whenever new directories should be ignored—and it’s easy to forget to do so.

Introducing repo.bazel

repo.bazel is a simple configuration file that allows us to achieve similar behavior, but with support for glob patterns. It is a relatively recent addition to Bazel, introduced around the same time as bzlmod.

An example repo.bazel file looks like this:

ignore_directories([
    # Ignore all .build directories produced by Swift Package Manager
    "**/.build",
    # Ignore Node modules directories
    "**/node_modules",
])

And that’s it.

Conclusion

This approach builds on the same idea as .bazelignore, but adds a few quality-of-life improvements—most notably, support for glob patterns.

For more information, see the official Bazel documentation.