README.md

Rust Protobuf Rules

Rules

• rust_proto_library
• rust_grpc_library

Overview

These build rules are used for building protobufs/gRPC in Rust with Bazel.

See the protobuf example for a more complete example of use.

Setup

To use the Rust proto rules, add the following to your WORKSPACE file to add the external repositories for the Rust proto toolchain (in addition to the rust rules setup):

load("@io_bazel_rules_rust//proto:repositories.bzl", "rust_proto_repositories")

rust_proto_repositories()

This will load crate dependencies of protobuf that are generated using cargo raze inside the rules_rust repository. However, using those dependencies might conflict with other uses of cargo raze. If you need to change those dependencies, please see the dedicated section below.

rust_proto_library

rust_proto_library(name, deps)

Builds a Rust library crate from a set of proto_library-s.

Attributes
name	Name, required A unique name for this rule.
deps	List of labels, required list of proto_compile dependencies that will be built. One crate for each proto_compile will be created with the corresponding stubs.

Example

load("@io_bazel_rules_rust//proto:proto.bzl", "rust_proto_library")
load("@io_bazel_rules_rust//proto:toolchain.bzl", "PROTO_COMPILE_DEPS")

proto_compile(
    name = "my_proto",
    srcs = ["my.proto"]
)

proto_rust_library(
    name = "rust",
    deps = [":my_proto"],
)

rust_binary(
    name = "my_proto_binary",
    srcs = ["my_proto_binary.rs"],
    deps = [":rust"] + PROTO_COMPILE_DEPS,
)

rust_grpc_library

rust_grpc_library(name, deps)

Builds a Rust library crate from a set of proto_library-s suitable for gRPC.

Attributes
name	Name, required A unique name for this rule.
deps	List of labels, required list of proto_compile dependencies that will be built. One crate for each proto_compile will be created with the corresponding gRPC stubs.

Example

load("@io_bazel_rules_rust//proto:proto.bzl", "rust_grpc_library")
load("@io_bazel_rules_rust//proto:toolchain.bzl", "GRPC_COMPILE_DEPS")

proto_compile(
    name = "my_proto",
    srcs = ["my.proto"]
)

rust_grpc_library(
    name = "rust",
    deps = [":my_proto"],
)

rust_binary(
    name = "my_service",
    srcs = ["my_service.rs"],
    deps = [":rust"] + GRPC_COMPILE_DEPS,
)

Customizing dependencies

These rules depends on the protobuf and the grpc crates in addition to the protobuf compiler. To do so the rust_proto_repositories import the given crates using file generated with cargo raze.

If you want to either change the protobuf and gRPC rust compilers, or to simply use cargo raze in a more complex scenario (with more dependencies), you must redefine those dependencies.

To do this, once you imported th needed dependencies (see our Cargo.toml file to see the default dependencies), you need to point to the correct toolchain, to do so you can create a BUILD file with the toolchain definition, for example:

load("@io_bazel_rules_rust//proto:toolchain.bzl", "rust_proto_toolchain")

toolchain(
    name = "toolchain",
    toolchain = ":toolchain-impl",
    toolchain_type = "@io_bazel_rules_rust//proto:toolchain",
)

rust_proto_toolchain(
    name = "toolchain-impl",
    # Path to the protobuf compiler.
    protoc = "@com_google_protobuf//:protoc",
    # Compile-time dependencies for gRPC crates.
    grpc_compile_deps = [
      "//cargo_raze/remote:protobuf",
      "//cargo_raze/remote:grpc",
      "//cargo_raze/remote:tls_api",
      "//cargo_raze/remote:tls_api_stub",
    ]
    # Protobuf compiler plugin to generate rust gRPC stubs.
    grpc_plugin = "//cargo_raze/remote:cargo_bin_protoc_gen_rust_grpc",
    # Compile-time dependencies for protobuf crates.
    proto_compile_deps = ["//cargo_raze/remote:protobuf"],
    # Protobuf compiler plugin to generate rust protobuf stubs.
    proto_plugin = "//cargo_raze/remote:cargo_bin_protoc_gen_rust",
)

Finally, now that you have your own toolchain, you need to register it by inserting the following statement in your WORKSPACE file:

register_toolchains(["//package:toolchain"])