Contributions are very welcome on this project. Issues should be raised for bugs and feature requests. Pull requests should be targeted at the master branch and will run against CI.


The rules in the repo are generated by the code in tools/rulegen and the output rules should therefore not be edited directly. However, if you are not comfortable editing this code, please submit a PR with just the output files edited and we’ll help update the generator to get the desired result.

Code Layout

Each language {lang} has a top-level subdirectory that contains:

  1. docs/{lang}.rst: Generated documentation for the language rules

  2. {lang}/repositories.bzl: Macro functions that declare repository rule dependencies for that language

  3. {lang}/{rule}.bzl: Rule implementations of the form {lang}_{kind}_{type}, where kind is one of proto|grpc and type is one of compile|library

  4. {lang}/BUILD.bazel: proto_plugin() declarations for the available plugins for the language

  5. example/{lang}/{rule}/: Generated WORKSPACE and BUILD.bazel demonstrating standalone usage of the rules

  6. {lang}/example/routeguide/: Example routeguide example implementation, if possible

Rule Generation

To help maintain consistency of the rule implementations and documentation, all of the rule implementations are generated by the tool //tools/rulegen. Changes in the main README.rst should be placed in tools/rulegen/README.header.rst or tools/rulegen/README.footer.rst`. Changes to generated rules should be put in the source files (example: tools/rulegen/java.go).