docs/index.md

rust_binary

Builds a Rust binary crate.

Example:

Suppose you have the following directory structure for a Rust project with a library crate, hello_lib, and a binary crate, hello_world that uses the hello_lib library:

[workspace]/
    WORKSPACE
    hello_lib/
        BUILD
        src/
            lib.rs
    hello_world/
        BUILD
        src/
            main.rs

hello_lib/src/lib.rs:

pub struct Greeter {
    greeting: String,
}

impl Greeter {
    pub fn new(greeting: &str) -> Greeter {
        Greeter { greeting: greeting.to_string(), }
    }

    pub fn greet(&self, thing: &str) {
        println!("{} {}", &self.greeting, thing);
    }
}

hello_lib/BUILD:

package(default_visibility = ["//visibility:public"])

load("@io_bazel_rules_rust//rust:rust.bzl", "rust_library")

rust_library(
    name = "hello_lib",
    srcs = ["src/lib.rs"],
)

hello_world/src/main.rs:

extern crate hello_lib;

fn main() {
    let hello = hello_lib::Greeter::new("Hello");
    hello.greet("world");
}

hello_world/BUILD:

load("@io_bazel_rules_rust//rust:rust.bzl", "rust_binary")

rust_binary(
    name = "hello_world",
    srcs = ["src/main.rs"],
    deps = ["//hello_lib"],
)

Build and run hello_world:

$ bazel run //hello_world
INFO: Found 1 target...
Target //examples/rust/hello_world:hello_world up-to-date:
  bazel-bin/examples/rust/hello_world/hello_world
INFO: Elapsed time: 1.308s, Critical Path: 1.22s

INFO: Running command line: bazel-bin/examples/rust/hello_world/hello_world
Hello world

Attributes

Features are defined in the code using the #[cfg(feature = "foo")] configuration option. The features listed here will be passed to rustc with --cfg feature="${feature_name}" flags. crate_root Label; optional The file that will be passed to rustc to be used for building this crate.

If crate_root is not set, then this rule will look for a lib.rs file (or main.rs for rust_binary) or the single file in srcs if srcs contains only one file. data List of labels; optional List of files used by this rule at runtime.

This attribute can be used to specify any data files that are embedded into the library, such as via the include_str! macro. deps List of labels; optional List of other libraries to be linked to this library target.

These can be either other rust_library targets or cc_library targets if linking a native library. edition String; optional The rust edition to use for this crate. Defaults to the edition specified in the rust_toolchain. out_dir_tar Label; optional An optional tar or tar.gz file unpacked and passed as OUT_DIR.

Many library crates in the Rust ecosystem require sources to be provided to them in the form of an OUT_DIR argument. This argument can be used to supply the contents of this directory. rustc_flags List of strings; optional List of compiler flags passed to rustc. srcs List of labels; optional List of Rust .rs source files used to build the library.

If srcs contains more than one file, then there must be a file either named lib.rs. Otherwise, crate_root must be set to the source file that is the root of the crate to be passed to rustc to build this crate. version String; optional A version to inject in the cargo environment variable.

rust_doc

Attributes

rust_doc_test

Runs Rust documentation tests.

Example:

Suppose you have the following directory structure for a Rust library crate:

[workspace]/
  WORKSPACE
  hello_lib/
      BUILD
      src/
          lib.rs

To run documentation tests for the hello_lib crate, define a rust_doc_test target that depends on the hello_lib rust_library target:

package(default_visibility = ["//visibility:public"])

load("@io_bazel_rules_rust//rust:rust.bzl", "rust_library", "rust_doc_test")

rust_library(
    name = "hello_lib",
    srcs = ["src/lib.rs"],
)

rust_doc_test(
    name = "hello_lib_doc_test",
    dep = ":hello_lib",
)

Running bazel test //hello_lib:hello_lib_doc_test will run all documentation tests for the hello_lib library crate.

Attributes

rust_doc_test can run documentation tests for the source files of rust_library or rust_binary targets.

rust_grpc_library

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

Example:

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

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"] + GRPC_COMPILE_DEPS,
)

Attributes

rust_library

Builds a Rust library crate.

Example:

Suppose you have the following directory structure for a simple Rust library crate:

[workspace]/
    WORKSPACE
    hello_lib/
        BUILD
        src/
            greeter.rs
            lib.rs

hello_lib/src/greeter.rs:

pub struct Greeter {
    greeting: String,
}

impl Greeter {
    pub fn new(greeting: &str) -> Greeter {
        Greeter { greeting: greeting.to_string(), }
    }

    pub fn greet(&self, thing: &str) {
        println!("{} {}", &self.greeting, thing);
    }
}

hello_lib/src/lib.rs:

pub mod greeter;

hello_lib/BUILD:

package(default_visibility = ["//visibility:public"])

load("@io_bazel_rules_rust//rust:rust.bzl", "rust_library")

rust_library(
    name = "hello_lib",
    srcs = [
        "src/greeter.rs",
        "src/lib.rs",
    ],
)

Build the library:

$ bazel build //hello_lib
INFO: Found 1 target...
Target //examples/rust/hello_lib:hello_lib up-to-date:
  bazel-bin/examples/rust/hello_lib/libhello_lib.rlib
INFO: Elapsed time: 1.245s, Critical Path: 1.01s

Attributes

If crate_root is not set, then this rule will look for a lib.rs file (or main.rs for rust_binary) or the single file in srcs if srcs contains only one file. crate_type String; optional The type of linkage to use for building this library. Options include “lib”, “rlib”, “dylib”, “cdylib”, “staticlib”, and “proc-macro”.

The exact output file will depend on the toolchain used. data List of labels; optional List of files used by this rule at runtime.

rust_proto_library

Builds a Rust library crate from a set of proto_librarys.

Example:

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

proto_library(
    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,
)

Attributes

rust_proto_toolchain

Declares a Rust Proto toolchain for use.

This is used to configure proto compilation and can be used to set different protobuf compiler plugin.

Example:

Suppose a new nicer gRPC plugin has came out. The new plugin can be used in Bazel by defining a new toolchain definition and declaration:

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

rust_proto_toolchain(
   name="rust_proto_impl",
   grpc_plugin="@rust_grpc//:grpc_plugin",
   grpc_compile_deps=["@rust_grpc//:grpc_deps"],
)

toolchain(
    name="rust_proto",
    exec_compatible_with = [
        "@platforms//cpu:cpuX",
    ],
    target_compatible_with = [
        "@platforms//cpu:cpuX",
    ],
    toolchain = ":rust_proto_impl",
)

Then, either add the label of the toolchain rule to register_toolchains in the WORKSPACE, or pass it to the “--extra_toolchains” flag for Bazel, and it will be used.

See @io_bazel_rules_rust//proto:BUILD for examples of defining the toolchain.

Attributes

rust_test

Builds a Rust test crate.

Examples:

Suppose you have the following directory structure for a Rust library crate with unit test code in the library sources:

[workspace]/
    WORKSPACE
    hello_lib/
        BUILD
        src/
            lib.rs

hello_lib/src/lib.rs:

pub struct Greeter {
    greeting: String,
}

impl Greeter {
    pub fn new(greeting: &str) -> Greeter {
        Greeter { greeting: greeting.to_string(), }
    }

    pub fn greet(&self, thing: &str) {
        println!("{} {}", &self.greeting, thing);
    }
}

#[cfg(test)]
mod test {
    use super::Greeter;

    #[test]
    fn test_greeting() {
        let hello = Greeter::new("Hi");
        assert_eq!("Hi Rust", hello.greeting("Rust"));
    }
}

To build and run the tests, simply add a rust_test rule with no srcs and only depends on the hello_lib rust_library target:

hello_lib/BUILD:

package(default_visibility = ["//visibility:public"])

load("@io_bazel_rules_rust//rust:rust.bzl", "rust_library", "rust_test")

rust_library(
    name = "hello_lib",
    srcs = ["src/lib.rs"],
)

rust_test(
    name = "hello_lib_test",
    deps = [":hello_lib"],
)

Run the test with bazel build //hello_lib:hello_lib_test.

Example: `test` directory

Integration tests that live in the tests directory, they are essentially built as separate crates. Suppose you have the following directory structure where greeting.rs is an integration test for the hello_lib library crate:

[workspace]/
    WORKSPACE
    hello_lib/
        BUILD
        src/
            lib.rs
        tests/
            greeting.rs

hello_lib/tests/greeting.rs:

extern crate hello_lib;

use hello_lib;

#[test]
fn test_greeting() {
    let hello = greeter::Greeter::new("Hello");
    assert_eq!("Hello world", hello.greeting("world"));
}

To build the greeting.rs integration test, simply add a rust_test target with greeting.rs in srcs and a dependency on the hello_lib target:

hello_lib/BUILD:

package(default_visibility = ["//visibility:public"])

load("@io_bazel_rules_rust//rust:rust.bzl", "rust_library", "rust_test")

rust_library(
    name = "hello_lib",
    srcs = ["src/lib.rs"],
)

rust_test(
    name = "greeting_test",
    srcs = ["tests/greeting.rs"],
    deps = [":hello_lib"],
)

Run the test with bazel build //hello_lib:hello_lib_test.

Attributes

rust_toolchain

Declares a Rust toolchain for use.

This is for declaring a custom toolchain, eg. for configuring a particular version of rust or supporting a new platform.

Example:

Suppose the core rust team has ported the compiler to a new target CPU, called cpuX. This support can be used in Bazel by defining a new toolchain definition and declaration:

load('@io_bazel_rules_rust//rust:toolchain.bzl', 'rust_toolchain')

rust_toolchain(
  name = "rust_cpuX_impl",
  rustc = "@rust_cpuX//:rustc",
  rustc_lib = "@rust_cpuX//:rustc_lib",
  rust_lib = "@rust_cpuX//:rust_lib",
  rust_doc = "@rust_cpuX//:rustdoc",
  staticlib_ext = ".a",
  dylib_ext = ".so",
  os = "linux",
)

toolchain(
  name = "rust_cpuX",
  exec_compatible_with = [
    "@platforms//cpu:cpuX",
  ],
  target_compatible_with = [
    "@platforms//cpu:cpuX",
  ],
  toolchain = ":rust_cpuX_impl",
)

Then, either add the label of the toolchain rule to register_toolchains in the WORKSPACE, or pass it to the "--extra_toolchains" flag for Bazel, and it will be used.

See @io_bazel_rules_rust//rust:repositories.bzl for examples of defining the @rust_cpuX repository with the actual binaries and libraries.

Attributes

rust_bindgen_toolchain

The tools required for the rust_bindgen rule.

rust_binary

Attributes

rust_doc

Attributes

rust_doc_test

Attributes

rust_grpc_library

Attributes

rust_library

Attributes

rust_proto_library

Attributes

rust_proto_toolchain

Attributes

rust_test

Example: test directory

Attributes

rust_toolchain

Attributes

rust_bindgen_toolchain

Attributes

Example: `test` directory