bazel repo: Starting a monorepo

I love monorepos and it was not the case prevously but I do think that monorepos shine in scenarios where:

• The code is tightly coupled together.
• One needs to ensure that resources on dev-tooling are efficiently spent.
• Migrations can be completed atomically.

Bazel is a really good build system, which allows reproducible and reasonably fast builds and the build system is configured with starlark, which can be used to write custom build rules, which allow to do linting or ensure consistency in packaging, etc.

I use bazel at work and I do not want to have to remember how to use two build systems or build my make targets and maintain them across multiple repositories. For this reason I decide to attempt to create a monorepo for myself, which would leverage bazel to:

• Write in multiple languages:
  • Rust
  • Go
  • Shell
• Have common packaging for all.
• Have reproducible builds and leverage caching in between the builds.

In a few hours I could complete a repository setup, which:

• Uses direnv to setup dev environment.
• Uses bazelisk to download the predefined bazel version.
• Setup a custom shellcheck rule which lints all files with .sh extension in my tools directory.
• Setup gazelle for upcoming go code.
• Setup buldifier to ensure that my BUILD.bazel files are formatted.
• Setup a CI script to ensure that my repository is clean.

See it at aignas/c.

Future ideas:

• Setup Travis CI or GitHub actions.
• A toy go CLI to iron out wrinkles in the gazelle and CI setup.
• A toy rust CLI to try out cargo-raze.
• Add tests for my shell scripts to test out sh_test rules.
• Generalize the shellcheck bazel rule and put it into a separate repository.
• Write a shfmt rule.
• bazel packaging rule for ArchLinux.
• Make the setup work on all OSes:
  • The bazelisk bootstrap script should check the OS before downloading bazelisk binary.
  • shellcheck rule should detect the OS and download the appropriate shellcheck binary for the host architecture.

Disclaimer: whilst I do intend to continue experimenting with this and post future updates here, I have other hobbies and it may take some time before I advance this experiment further.