rules_proto

rules_proto provides build rules for compiling protocol buffer files.

Overview

Each language ${LANG} has a top-level subdirectory that contains ~4 files:

deps.bzl: contains macro functions that declare repository rule dependencies for that language. There are typically 2 functions ${LANG}_proto_deps() and ${LANG}_grpc_deps(). If you only need proto support (any not grpc support), load the _proto_ macro, otherwise load the _grpc_ macro function and call it in your WORKSPACE.
compile.bzl: contains the rules ${LANG}_proto_compile and ${LANG}_grpc_compile (if available).
library.bzl: contains the rules ${LANG}_proto_library and ${LANG}_grpc_library (if available).
BUILD.bazel: contains proto_plugin() declarations for the available plugins. These are consumed by the ${LANG}_proto_compile and ${LANG}_grpc_compile rules.

The root directory contains the base rule defintions:

plugin.bzl: A build rule that defines the name, tool binary, and options for a particular proto plugin.
compile.bzl: A build rule that contains the proto_compile rule. This rule calls protoc with a given list of plugins and generates output files.

Follow the pattern seen in the multiple examples in this repository. The basic idea is:

Load the plugin rule: load("@org_pubref_rules_proto//:plugin.bzl", "proto_plugin").
Define the rule, giving it a name, options (not mandatory), tool, and outputs.
tool is a label that refers to the binary executable for the plugin itself.
outputs is a list of strings that predicts the pattern of files generated by the plugin. Specifying outputs is the only attribute that requires much mental effort.