rules_rust_protobuf

These build rules are used for building protobufs/gRPC in Rust with Bazel using rust-protobuf.

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("@rules_rust//proto/protobuf:repositories.bzl", "rust_proto_protobuf_dependencies", "rust_proto_protobuf_register_toolchains")

rust_proto_protobuf_dependencies()

rust_proto_protobuf_register_toolchains()

load("@rules_rust//proto/protobuf:transitive_repositories.bzl", "rust_proto_protobuf_transitive_repositories")

rust_proto_protobuf_transitive_repositories()

This will load the required dependencies for the rust-protobuf rules. It will also register a default toolchain for the rust_proto_library and rust_grpc_library rules.

To customize the rust_proto_library and rust_grpc_library toolchain, please see the section Customizing rust-protobuf Dependencies.

For additional information about Bazel toolchains, see here.

Customizing `rust-protobuf` Dependencies

These rules depend on the protobuf and the grpc crates in addition to the protobuf compiler. To obtain these crates, rust_proto_repositories imports the given crates using BUILD files generated with crate_universe.

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

To do this, once you've imported the needed dependencies (see our @rules_rust//proto/protobuf/3rdparty/BUILD.bazel file to see the default dependencies), you need to create your own toolchain. To do so you can create a BUILD file with your toolchain definition, for example:

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

rust_proto_toolchain(
    name = "proto-toolchain-impl",
    # Path to the protobuf compiler.
    protoc = "@com_google_protobuf//:protoc",
    # Protobuf compiler plugin to generate rust gRPC stubs.
    grpc_plugin = "//3rdparty/crates:cargo_bin_protoc_gen_rust_grpc",
    # Protobuf compiler plugin to generate rust protobuf stubs.
    proto_plugin = "//3rdparty/crates:cargo_bin_protoc_gen_rust",
)

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

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

register_toolchains("//my/toolchains:proto-toolchain")

Finally, you might want to set the rust_deps attribute in rust_proto_library and rust_grpc_library to change the compile-time dependencies:

rust_proto_library(
    ...
    rust_deps = ["//3rdparty/crates:protobuf"],
    ...
)

rust_grpc_library(
    ...
    rust_deps = [
        "//3rdparty/crates:protobuf",
        "//3rdparty/crates:grpc",
        "//3rdparty/crates:tls_api",
        "//3rdparty/crates:tls_api_stub",
    ],
    ...
)

Note: Ideally, we would inject those dependencies from the toolchain, but due to bazelbuild/bazel#6889 all dependencies added via the toolchain ends-up being in the wrong configuration.

rust_grpc_library

Builds a Rust library crate from a set of proto_librarys suitable for gRPC.

Example:

load("@rules_rust_protobuf//:defs.bzl", "rust_grpc_library")

proto_library(
    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"],
)

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
deps	List of proto_library dependencies that will be built. One crate for each proto_library will be created with the corresponding gRPC stubs.	List of labels	required
crate_name	Crate name to use for this target. This must be a valid Rust identifier, i.e. it may contain only alphanumeric characters and underscores. Defaults to the target name, with any hyphens replaced by underscores.	String	optional	`""`
rust_deps	The crates the generated library depends on.	List of labels	optional	`[]`
rustc_flags	List of compiler flags passed to `rustc`. These strings are subject to Make variable expansion for predefined source/output path variables like `$location`, `$execpath`, and `$rootpath`. This expansion is useful if you wish to pass a generated file of arguments to rustc: `@$(location //package:target)`.	List of strings	optional	`[]`

rust_proto_library

Builds a Rust library crate from a set of proto_librarys.