Crate Universe

Crate Universe is a set of Bazel rule for generating Rust targets using Cargo.

This doc describes using crate_universe from a WORKSPACE file.

If you're using bzlmod, please see the bzlmod equivalent of this doc.

Setup

After loading rules_rust in your workspace, set the following to begin using crate_universe:

load("@rules_rust//crate_universe:repositories.bzl", "crate_universe_dependencies")

crate_universe_dependencies()

Note that if the current version of rules_rust is not a release artifact, you may need to set additional flags such as bootstrap = True on the crate_universe_dependencies call above or crates_repository::generator_urls in uses of crates_repository.

Utility Macros

crate_universe_dependencies
crate.annotation
crate.select
crate.spec
crate.workspace_member
render_config
splicing_config

Workflows

The crates_repository rule (the primary repository rule of rules_rust's cargo support) supports a number of different ways users can express and organize their dependencies. The most common are listed below though there are more to be found in the ./examples/crate_universe directory.

Cargo Workspaces

One of the simpler ways to wire up dependencies would be to first structure your project into a Cargo workspace. The crates_repository rule can ingest a root Cargo.toml file and generate dependencies from there.

load("@rules_rust//crate_universe:defs.bzl", "crates_repository")

crates_repository(
    name = "crate_index",
    cargo_lockfile = "//:Cargo.lock",
    lockfile = "//:Cargo.Bazel.lock",
    manifests = ["//:Cargo.toml"],
)

load("@crate_index//:defs.bzl", "crate_repositories")

crate_repositories()

The generated crates_repository contains helper macros which make collecting dependencies for Bazel targets simpler. Notably, the all_crate_deps and aliases macros (see Dependencies API) commonly allow the Cargo.toml files to be the single source of truth for dependencies. Since these macros come from the generated repository, the dependencies and alias definitions they return will automatically update BUILD targets.

load("@crate_index//:defs.bzl", "aliases", "all_crate_deps")
load("@rules_rust//rust:defs.bzl", "rust_library", "rust_test")

rust_library(
    name = "lib",
    aliases = aliases(),
    deps = all_crate_deps(
        normal = True,
    ),
    proc_macro_deps = all_crate_deps(
        proc_macro = True,
    ),
)

rust_test(
    name = "unit_test",
    crate = ":lib",
    aliases = aliases(
        normal_dev = True,
        proc_macro_dev = True,
    ),
    deps = all_crate_deps(
        normal_dev = True,
    ),
    proc_macro_deps = all_crate_deps(
        proc_macro_dev = True,
    ),
)

Direct Packages

In cases where Rust targets have heavy interractions with other Bazel targests (Cc, Proto, etc.), maintaining Cargo.toml files may have deminishing returns as things like rust-analyzer begin to be confused about missing targets or environment variables defined only in Bazel. In workspaces like this, it may be desirable to have a “Cargo free” setup. crates_repository supports this through the packages attribute.

load("@rules_rust//crate_universe:defs.bzl", "crate", "crates_repository", "render_config")

crates_repository(
    name = "crate_index",
    cargo_lockfile = "//:Cargo.lock",
    lockfile = "//:Cargo.Bazel.lock",
    packages = {
        "async-trait": crate.spec(
            version = "0.1.51",
        ),
        "mockall": crate.spec(
            version = "0.10.2",
        ),
        "tokio": crate.spec(
            version = "1.12.0",
        ),
    },
    # Setting the default package name to `""` forces the use of the macros defined in this repository
    # to always use the root package when looking for dependencies or aliases. This should be considered
    # optional as the repository also exposes alises for easy access to all dependencies.
    render_config = render_config(
        default_package_name = ""
    ),
)

load("@crate_index//:defs.bzl", "crate_repositories")

crate_repositories()

Consuming dependencies may be more ergonomic in this case through the aliases defined in the new repository.

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

rust_library(
    name = "lib",
    deps = [
        "@crate_index//:tokio",
    ],
    proc_macro_deps = [
        "@crate_index//:async-trait",
    ],
)

rust_test(
    name = "unit_test",
    crate = ":lib",
    deps = [
        "@crate_index//:mockall",
    ],
)

Binary dependencies

Neither of the above approaches supports depending on binary-only packages.

In order to depend on a Cargo package that contains binaries and no library, you will need to do one of the following:

Fork the package to add an empty lib.rs, which makes the package visible to Cargo metadata and compatible with the above approaches;
Or handwrite your own build target for the binary, use http_archive to import its source code, and use crates_repository to make build targets for its dependencies. This is demonstrated below using the rustfilt crate as an example.

# in WORKSPACE.bazel

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "rustfilt",
    build_file = "//rustfilt:BUILD.rustfilt.bazel",
    sha256 = "c8d748b182c8f95224336d20dcc5609598af612581ce60cfb29da4dc8d0091f2",
    strip_prefix = "rustfilt-0.2.1",
    type = "tar.gz",
    urls = ["https://static.crates.io/crates/rustfilt/rustfilt-0.2.1.crate"],
)

load("@rules_rust//crate_universe:defs.bzl", "crates_repository")

crates_repository(
    name = "rustfilt_deps",
    cargo_lockfile = "//rustfilt:Cargo.lock",
    manifests = ["@rustfilt//:Cargo.toml"],
)

load("@rustfilt_deps//:defs.bzl", rustfilt_deps = "crate_repositories")

rustfilt_deps()

# in rustfilt/BUILD.rustfilt.bazel

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

rust_binary(
    name = "rustfilt",
    srcs = glob(["src/**/*.rs"]),
    edition = "2018",
    deps = [
        "@rustfilt_deps//:clap",
        "@rustfilt_deps//:lazy_static",
        "@rustfilt_deps//:regex",
        "@rustfilt_deps//:rustc-demangle",
    ],
)

If you use either crates_repository or crates_vendor to depend on a Cargo package that contains both a library crate and binaries, by default only the library gets made available to Bazel. To generate Bazel targets for the binary crates as well, you must opt in to it with an annotation on the package:

load("@rules_rust//crate_universe:defs.bzl", "crates_repository", "crate")

crates_repository(
    name = "crate_index",
    annotations = {
        "thepackage": [crate.annotation(
            gen_binaries = True,
            # Or, to expose just a subset of the package's binaries by name:
            gen_binaries = ["rustfilt"],
        )],
    },
    # Or, to expose every binary of every package:
    generate_binaries = True,
    ...
)

Dependencies API

After rendering dependencies, convenience macros may also be generated to provide convenient accessors to larger sections of the dependency graph.

aliases
crate_deps
all_crate_deps
crate_repositories

Building crates with complicated dependencies

Some crates have build.rs scripts which are complicated to run. Typically these build C++ (or other languages), or attempt to find pre-installed libraries on the build machine.

There are a few approaches to making sure these run:

Some things work without intervention

Some build scripts will happily run without any support needed.

rules_rust already supplies a configured C++ toolchain as input to build script execution, and sets variables like CC, CXX, LD, LDFLAGS, etc as needed. Many crates which invoke a compiler with the default environment, or forward these env vars, will Just Work (e.g. if using cc-rs).

rules_rust is open to PRs which make build scripts more likely to work by default with intervention assuming they‘re broadly applicable (e.g. setting extra widely-known env vars is probably fine, wiring up additional toolchains like cmake that aren’t present by default for most Bazel users probably isn't).

Supplying extra tools to build

Some build scripts can be made to work by pulling in some extra files and making them available to the build script.

Commonly this is done by passing the file to the build_script_data annotation for the crate, and using build_script_env to tell the build script where the file is. That env var may often use $(execroot) to get the path to the label, or $${pwd}/ as a prefix if the path given is relative to the execroot (as will frequently happen when using a toolchain).A

There is an example of this in the “complicated dependencies” section of https://github.com/bazelbuild/rules_rust/blob/main/examples/crate_universe/WORKSPACE.bazel which builds libz-ng-sys.

Building with Bazel and supplying via an override

Some build scripts have hooks to allow replacing parts that are complicated to build with output prepared by Bazel.

We can use those hooks by specifying paths (generally using the build_script_data and build_script_env annotations) and pointing them at labels which Bazel will then build. These env vars may often use $(execroot) to get the path to the label, or $${pwd}/ as a prefix if the path given is relative to the execroot (as will frequently happen when using a toolchain).

There is an example of this in the “complicated dependencies” section of https://github.com/bazelbuild/rules_rust/blob/main/examples/crate_universe/WORKSPACE.bazel which builds boring-sys.

crates_vendor

A rule for defining Rust dependencies (crates) and writing targets for them to the current workspace. This rule is useful for users whose workspaces are expected to be consumed in other workspaces as the rendered BUILD files reduce the number of workspace dependencies, allowing for easier loads. This rule handles all the same workflows crate_universe rules do.

Example:

Given the following workspace structure:

[workspace]/
    WORKSPACE
    BUILD
    Cargo.toml
    3rdparty/
        BUILD
    src/
        main.rs

The following is something that'd be found in 3rdparty/BUILD:

load("@rules_rust//crate_universe:defs.bzl", "crates_vendor", "crate")

crates_vendor(
    name = "crates_vendor",
    annotations = {
        "rand": [crate.annotation(
            default_features = False,
            features = ["small_rng"],
        )],
    },
    cargo_lockfile = "//:Cargo.Bazel.lock",
    manifests = ["//:Cargo.toml"],
    mode = "remote",
    vendor_path = "crates",
    tags = ["manual"],
)

The above creates a target that can be run to write BUILD files into the 3rdparty directory next to where the target is defined. To run it, simply call:

bazel run //3rdparty:crates_vendor

Repinning / Updating Dependencies

Repinning dependencies is controlled by both the CARGO_BAZEL_REPIN environment variable or the --repin flag to the crates_vendor binary. To update dependencies, simply add the flag ro your bazel run invocation.

bazel run //3rdparty:crates_vendor -- --repin

Under the hood, --repin will trigger a cargo update call against the generated workspace. The following table describes how to control particular values passed to the cargo update command.

Value	Cargo command
Any of [`true`, `1`, `yes`, `on`, `workspace`]	`cargo update --workspace`
Any of [`full`, `eager`, `all`]	`cargo update`
`package_name`	`cargo upgrade --package package_name`
`package_name@1.2.3`	`cargo upgrade --package package_name --precise 1.2.3`

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
annotations	Extra settings to apply to crates. See crate.annotation.	Dictionary: String -> List of strings	optional	`{}`
bazel	The path to a bazel binary used to locate the output_base for the current workspace.	Label	optional	`None`
buildifier	The path to a buildifier binary used to format generated BUILD files.	Label	optional	`"@rules_rust//crate_universe/private/vendor:buildifier"`
cargo_bazel	The cargo-bazel binary to use for vendoring. If this attribute is not set, then a `CARGO_BAZEL_GENERATOR_PATH` action env will be used.	Label	optional	`"@@cargo_bazel_bootstrap//:binary"`
cargo_config	A Cargo configuration file.	Label	optional	`None`
cargo_lockfile	The path to an existing `Cargo.lock` file	Label	optional	`None`
generate_binaries	Whether to generate `rust_binary` targets for all the binary crates in every package. By default only the `rust_library` targets are generated.	Boolean	optional	`False`
generate_build_scripts	Whether or not to generate cargo build scripts by default.	Boolean	optional	`True`
generate_target_compatible_with	DEPRECATED: Moved to `render_config`.	Boolean	optional	`True`
manifests	A list of Cargo manifests (`Cargo.toml` files).	List of labels	optional	`[]`
mode	Flags determining how crates should be vendored. `local` is where crate source and BUILD files are written to the repository. `remote` is where only BUILD files are written and repository rules used to fetch source code.	String	optional	`"remote"`
packages	A set of crates (packages) specifications to depend on. See crate.spec.	Dictionary: String -> String	optional	`{}`
render_config	The configuration flags to use for rendering. Use `//crate_universe:defs.bzl\%render_config` to generate the value for this field. If unset, the defaults defined there will be used.	String	optional	`""`
repository_name	The name of the repository to generate for `remote` vendor modes. If unset, the label name will be used	String	optional	`""`
splicing_config	The configuration flags to use for splicing Cargo maniests. Use `//crate_universe:defs.bzl\%rsplicing_config` to generate the value for this field. If unset, the defaults defined there will be used.	String	optional	`""`
supported_platform_triples	A set of all platform triples to consider when generating dependencies.	List of strings	optional	["aarch64-unknown-linux-gnu", "aarch64-unknown-nixos-gnu", "i686-apple-darwin", "i686-pc-windows-msvc", "i686-unknown-linux-gnu", "x86_64-apple-darwin", "x86_64-pc-windows-msvc", "x86_64-unknown-linux-gnu", "x86_64-unknown-nixos-gnu", "aarch64-apple-darwin", "aarch64-apple-ios-sim", "aarch64-apple-ios", "aarch64-fuchsia", "aarch64-linux-android", "aarch64-pc-windows-msvc", "arm-unknown-linux-gnueabi", "armv7-linux-androideabi", "armv7-unknown-linux-gnueabi", "i686-linux-android", "i686-unknown-freebsd", "powerpc-unknown-linux-gnu", "riscv32imc-unknown-none-elf", "riscv64gc-unknown-none-elf", "s390x-unknown-linux-gnu", "thumbv7em-none-eabi", "thumbv8m.main-none-eabi", "wasm32-unknown-unknown", "wasm32-wasi", "x86_64-apple-ios", "x86_64-fuchsia", "x86_64-linux-android", "x86_64-unknown-freebsd", "x86_64-unknown-none", "aarch64-unknown-nto-qnx710"]
vendor_path	The path to a directory to write files into. Absolute paths will be treated as relative to the workspace root	String	optional	`"crates"`

aliases

Produces a map of Crate alias names to their original label

If no dependency kinds are specified, normal and proc_macro are used by default. Setting any one flag will otherwise determine the contents of the returned dict.

PARAMETERS

Name	Description	Default Value
normal	If True, normal dependencies are included in the output list.	`False`
normal_dev	If True, normal dev dependencies will be included in the output list..	`False`
proc_macro	If True, proc_macro dependencies are included in the output list.	`False`
proc_macro_dev	If True, dev proc_macro dependencies are included in the output list.	`False`
build	If True, build dependencies are included in the output list.	`False`
build_proc_macro	If True, build proc_macro dependencies are included in the output list.	`False`
package_name	The package name of the set of dependencies to look up. Defaults to `native.package_name()` when unset.	`None`

RETURNS

dict: The aliases of all associated packages

all_crate_deps

Finds the fully qualified label of all requested direct crate dependencies for the package where this macro is called.

If no parameters are set, all normal dependencies are returned. Setting any one flag will otherwise impact the contents of the returned list.

PARAMETERS

Name	Description	Default Value
normal	If True, normal dependencies are included in the output list.	`False`
normal_dev	If True, normal dev dependencies will be included in the output list..	`False`
proc_macro	If True, proc_macro dependencies are included in the output list.	`False`
proc_macro_dev	If True, dev proc_macro dependencies are included in the output list.	`False`
build	If True, build dependencies are included in the output list.	`False`
build_proc_macro	If True, build proc_macro dependencies are included in the output list.	`False`
package_name	The package name of the set of dependencies to look up. Defaults to `native.package_name()` when unset.	`None`

RETURNS

list: A list of labels to generated rust targets (str)

crate.annotation

A collection of extra attributes and settings for a particular crate

PARAMETERS

Name	Description	Default Value
version	The version or semver-conditions to match with a crate. The wildcard `*` matches any version, including prerelease versions.	`"*"`
additive_build_file	A file containing extra contents to write to the bottom of generated BUILD files.	`None`
additive_build_file_content	Extra contents to write to the bottom of generated BUILD files.	`None`
alias_rule	Alias rule to use instead of `native.alias()`. Overrides render_config's ‘default_alias_rule’.	`None`
build_script_data	A list of labels to add to a crate's `cargo_build_script::data` attribute.	`None`
build_script_tools	A list of labels to add to a crate's `cargo_build_script::tools` attribute.	`None`
build_script_data_glob	A list of glob patterns to add to a crate's `cargo_build_script::data` attribute.	`None`
build_script_deps	A list of labels to add to a crate's `cargo_build_script::deps` attribute.	`None`
build_script_env	Additional environment variables to set on a crate's `cargo_build_script::env` attribute.	`None`
build_script_proc_macro_deps	A list of labels to add to a crate's `cargo_build_script::proc_macro_deps` attribute.	`None`
build_script_rundir	An override for the build script's rundir attribute.	`None`
build_script_rustc_env	Additional environment variables to set on a crate's `cargo_build_script::env` attribute.	`None`
build_script_toolchains	A list of labels to set on a crates's `cargo_build_script::toolchains` attribute.	`None`
compile_data	A list of labels to add to a crate's `rust_library::compile_data` attribute.	`None`
compile_data_glob	A list of glob patterns to add to a crate's `rust_library::compile_data` attribute.	`None`
crate_features	A list of strings to add to a crate's `rust_library::crate_features` attribute.	`None`
data	A list of labels to add to a crate's `rust_library::data` attribute.	`None`
data_glob	A list of glob patterns to add to a crate's `rust_library::data` attribute.	`None`
deps	A list of labels to add to a crate's `rust_library::deps` attribute.	`None`
extra_aliased_targets	A list of targets to add to the generated aliases in the root crate_universe repository.	`None`
gen_binaries	As a list, the subset of the crate's bins that should get `rust_binary` targets produced. Or `True` to generate all, `False` to generate none.	`None`
disable_pipelining	If True, disables pipelining for library targets for this crate.	`False`
gen_build_script	An authorative flag to determine whether or not to produce `cargo_build_script` targets for the current crate.	`None`
patch_args	The `patch_args` attribute of a Bazel repository rule. See http_archive.patch_args	`None`
patch_tool	The `patch_tool` attribute of a Bazel repository rule. See http_archive.patch_tool	`None`
patches	The `patches` attribute of a Bazel repository rule. See http_archive.patches	`None`
proc_macro_deps	A list of labels to add to a crate's `rust_library::proc_macro_deps` attribute.	`None`
rustc_env	Additional variables to set on a crate's `rust_library::rustc_env` attribute.	`None`
rustc_env_files	A list of labels to set on a crate's `rust_library::rustc_env_files` attribute.	`None`
rustc_flags	A list of strings to set on a crate's `rust_library::rustc_flags` attribute.	`None`
shallow_since	An optional timestamp used for crates originating from a git repository instead of a crate registry. This flag optimizes fetching the source code.	`None`
override_targets	A dictionary of alternate tagets to use when something depends on this crate to allow the parent repo to provide its own version of this dependency. Keys can be `proc_marco`, `build_script`, `lib`, `bin`.	`None`

RETURNS

string: A json encoded string containing the specified version and separately all other inputs.

crate.select

A Starlark Select for crate.annotation().

PARAMETERS

Name	Description	Default Value
common	A value that applies to all configurations.	none
selects	A dict of `target_triple` to values.	none

RETURNS

struct: A struct representing the Starlark Select.

crate.spec

A constructor for a crate dependency.

See specifying dependencies in the Cargo book for more details.

PARAMETERS

Name	Description	Default Value
package	The explicit name of the package (used when attempting to alias a crate).	`None`
version	The exact version of the crate. Cannot be used with `git`.	`None`
artifact	Set to “bin” to pull in a binary crate as an artifact dependency. Requires a nightly Cargo.	`None`
lib	If using `artifact = "bin"`, additionally setting `lib = True` declares a dependency on both the package's library and binary, as opposed to just the binary.	`None`
default_features	Maps to the `default-features` flag.	`True`
features	A list of features to use for the crate	`[]`
git	The Git url to use for the crate. Cannot be used with `version`.	`None`
branch	The git branch of the remote crate. Tied with the `git` param. Only one of branch, tag or rev may be specified. Specifying `rev` is recommended for fully-reproducible builds.	`None`
tag	The git tag of the remote crate. Tied with the `git` param. Only one of branch, tag or rev may be specified. Specifying `rev` is recommended for fully-reproducible builds.	`None`
rev	The git revision of the remote crate. Tied with the `git` param. Only one of branch, tag or rev may be specified.	`None`

RETURNS

string: A json encoded string of all inputs

crate.workspace_member

Define information for extra workspace members

PARAMETERS

Name	Description	Default Value
version	The semver of the crate to download. Must be an exact version.	none
sha256	The sha256 checksum of the `.crate` file.	`None`

RETURNS

string: A json encoded string of all inputs

crate_deps

Finds the fully qualified label of the requested crates for the package where this macro is called.

PARAMETERS

Name	Description	Default Value
deps	The desired list of crate targets.	none
package_name	The package name of the set of dependencies to look up. Defaults to `native.package_name()`.	`None`

RETURNS

list: A list of labels to generated rust targets (str)

crate_repositories

A macro for defining repositories for all generated crates.

RETURNS

A list of repos visible to the module through the module extension.

crate_universe_dependencies

Define dependencies of the cargo-bazel Rust target

PARAMETERS

Name	Description	Default Value
rust_version	The version of rust to use when generating dependencies.	`"1.80.0"`
bootstrap	If true, a `cargo_bootstrap_repository` target will be generated.	`False`
kwargs	Arguments to pass through to cargo_bazel_bootstrap.	none

RETURNS

list[struct(repo=str, is_dev_dep=bool)]: A list of the repositories defined by this macro.

render_config

Various settings used to configure rendered outputs

The template parameters each support a select number of format keys. A description of each key can be found below where the supported keys for each template can be found in the parameter docs

key	definition
`name`	The name of the crate. Eg `tokio`
`repository`	The rendered repository name for the crate. Directly relates to `crate_repository_template`.
`triple`	A platform triple. Eg `x86_64-unknown-linux-gnu`
`version`	The crate version. Eg `1.2.3`
`target`	The library or binary target of the crate
`file`	The basename of a file

PARAMETERS

Name	Description	Default Value
build_file_template	The base template to use for BUILD file names. The available format keys are [`{name}`, {version}`].	`"//:BUILD.{name}-{version}.bazel"`
crate_label_template	The base template to use for crate labels. The available format keys are [`{repository}`, `{name}`, `{version}`, `{target}`].	`"@{repository}__{name}-{version}//:{target}"`
crate_repository_template	The base template to use for Crate label repository names. The available format keys are [`{repository}`, `{name}`, `{version}`].	`"{repository}__{name}-{version}"`
crates_module_template	The pattern to use for the `defs.bzl` and `BUILD.bazel` file names used for the crates module. The available format keys are [`{file}`].	`"//:{file}"`
default_alias_rule	Alias rule to use when generating aliases for all crates. Acceptable values are ‘alias’, ‘dbg’/‘fastbuild’/‘opt’ (transitions each crate's `compilation_mode`) or a string representing a rule in the form ‘<label to .bzl>:’ that takes a single label parameter ‘actual’. See ‘@crate_index//:alias_rules.bzl’ for an example.	`"alias"`
default_package_name	The default package name to use in the rendered macros. This affects the auto package detection of things like `all_crate_deps`.	`None`
generate_target_compatible_with	Whether to generate `target_compatible_with` annotations on the generated BUILD files. This catches a `target_triple`being targeted that isn't declared in `supported_platform_triples`.	`True`
platforms_template	The base template to use for platform names. See platforms documentation. The available format keys are [`{triple}`].	`"@rules_rust//rust/platform:{triple}"`
regen_command	An optional command to demonstrate how generated files should be regenerated.	`None`
vendor_mode	An optional configuration for rendirng content to be rendered into repositories.	`None`
generate_rules_license_metadata	Whether to generate rules license metedata	`False`

RETURNS

string: A json encoded struct to match the Rust config::RenderConfig struct

splicing_config

Various settings used to configure Cargo manifest splicing behavior.

PARAMETERS

Name	Description	Default Value
resolver_version	The resolver version to use in generated Cargo manifests. This flag is only used when splicing a manifest from direct package definitions. See `crates_repository::packages`.	`"2"`

RETURNS

str: A json encoded string of the parameters provided

crates_repository

A rule for defining and downloading Rust dependencies (crates). This rule handles all the same workflows crate_universe rules do.

Environment Variables:

variable	usage
`CARGO_BAZEL_GENERATOR_SHA256`	The sha256 checksum of the file located at `CARGO_BAZEL_GENERATOR_URL`
`CARGO_BAZEL_GENERATOR_URL`	The URL of a cargo-bazel binary. This variable takes precedence over attributes and can use `file://` for local paths
`CARGO_BAZEL_ISOLATED`	An authorative flag as to whether or not the `CARGO_HOME` environment variable should be isolated from the host configuration
`CARGO_BAZEL_REPIN`	An indicator that the dependencies represented by the rule should be regenerated. `REPIN` may also be used. See Repinning / Updating Dependencies for more details.
`CARGO_BAZEL_REPIN_ONLY`	A comma-delimited allowlist for rules to execute repinning. Can be useful if multiple instances of the repository rule are used in a Bazel workspace, but repinning should be limited to one of them.

Example:

Given the following workspace structure:

[workspace]/
    WORKSPACE.bazel
    BUILD.bazel
    Cargo.toml
    Cargo.Bazel.lock
    src/
        main.rs

The following is something that'd be found in the WORKSPACE file:

load("@rules_rust//crate_universe:defs.bzl", "crates_repository", "crate")

crates_repository(
    name = "crate_index",
    annotations = {
        "rand": [crate.annotation(
            default_features = False,
            features = ["small_rng"],
        )],
    },
    cargo_lockfile = "//:Cargo.Bazel.lock",
    lockfile = "//:cargo-bazel-lock.json",
    manifests = ["//:Cargo.toml"],
    # Should match the version represented by the currently registered `rust_toolchain`.
    rust_version = "1.60.0",
)

The above will create an external repository which contains aliases and macros for accessing Rust targets found in the dependency graph defined by the given manifests.

NOTE: The cargo_lockfile and lockfile must be manually created. The rule unfortunately does not yet create it on its own. When initially setting up this rule, an empty file should be created and then populated by repinning dependencies.

Repinning / Updating Dependencies

Dependency syncing and updating is done in the repository rule which means it's done during the analysis phase of builds. As mentioned in the environments variable table above, the CARGO_BAZEL_REPIN (or REPIN) environment variables can be used to force the rule to update dependencies and potentially render a new lockfile. Given an instance of this repository rule named crate_index, the easiest way to repin dependencies is to run:

CARGO_BAZEL_REPIN=1 bazel sync --only=crate_index

This will result in all dependencies being updated for a project. The CARGO_BAZEL_REPIN environment variable can also be used to customize how dependencies are updated. The following table shows translations from environment variable values to the equivilant cargo update command that is called behind the scenes to update dependencies.

Value	Cargo command
Any of [`true`, `1`, `yes`, `on`, `workspace`]	`cargo update --workspace`
Any of [`full`, `eager`, `all`]	`cargo update`
`package_name`	`cargo upgrade --package package_name`
`package_name@1.2.3`	`cargo upgrade --package package_name@1.2.3`
`package_name@1.2.3=4.5.6`	`cargo upgrade --package package_name@1.2.3 --precise=4.5.6`

If the crates_repository is used multiple times in the same Bazel workspace (e.g. for multiple independent Rust workspaces), it may additionally be useful to use the CARGO_BAZEL_REPIN_ONLY environment variable, which limits execution of the repinning to one or multiple instances of the crates_repository rule via a comma-delimited allowlist:

CARGO_BAZEL_REPIN=1 CARGO_BAZEL_REPIN_ONLY=crate_index bazel sync --only=crate_index

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this repository.	Name	required
annotations	Extra settings to apply to crates. See crate.annotation.	Dictionary: String -> List of strings	optional	`{}`
cargo_config	A Cargo configuration file	Label	optional	`None`
cargo_lockfile	The path used to store the `crates_repository` specific Cargo.lock file. In the case that your `crates_repository` corresponds directly with an existing `Cargo.toml` file which has a paired `Cargo.lock` file, that `Cargo.lock` file should be used here, which will keep the versions used by cargo and bazel in sync.	Label	required
generate_binaries	Whether to generate `rust_binary` targets for all the binary crates in every package. By default only the `rust_library` targets are generated.	Boolean	optional	`False`
generate_build_scripts	Whether or not to generate cargo build scripts by default.	Boolean	optional	`True`
generate_target_compatible_with	DEPRECATED: Moved to `render_config`.	Boolean	optional	`True`
generator	The absolute label of a generator. Eg. `@cargo_bazel_bootstrap//:cargo-bazel`. This is typically used when bootstrapping	String	optional	`""`
generator_sha256s	Dictionary of `host_triple` -> `sha256` for a `cargo-bazel` binary.	Dictionary: String -> String	optional	`{}`
generator_urls	URL template from which to download the `cargo-bazel` binary. `{host_triple}` and will be filled in according to the host platform.	Dictionary: String -> String	optional	`{}`
isolated	If true, `CARGO_HOME` will be overwritten to a directory within the generated repository in order to prevent other uses of Cargo from impacting having any effect on the generated targets produced by this rule. For users who either have multiple `crate_repository` definitions in a WORKSPACE or rapidly re-pin dependencies, setting this to false may improve build times. This variable is also controled by `CARGO_BAZEL_ISOLATED` environment variable.	Boolean	optional	`True`
lockfile	The path to a file to use for reproducible renderings. If set, this file must exist within the workspace (but can be empty) before this rule will work.	Label	optional	`None`
manifests	A list of Cargo manifests (`Cargo.toml` files).	List of labels	optional	`[]`
packages	A set of crates (packages) specifications to depend on. See crate.spec.	Dictionary: String -> String	optional	`{}`
quiet	If stdout and stderr should not be printed to the terminal.	Boolean	optional	`True`
render_config	The configuration flags to use for rendering. Use `//crate_universe:defs.bzl\%render_config` to generate the value for this field. If unset, the defaults defined there will be used.	String	optional	`""`
repin_instructions	Instructions to re-pin the repository if required. Many people have wrapper scripts for keeping dependencies up to date, and would like to point users to that instead of the default.	String	optional	`""`
repo_mapping	In `WORKSPACE` context only: a dictionary from local repository name to global repository name. This allows controls over workspace dependency resolution for dependencies of this repository. For example, an entry `"@foo": "@bar"` declares that, for any time this repository depends on `@foo` (such as a dependency on `@foo//some:target`, it should actually resolve that dependency within globally-declared `@bar` (`@bar//some:target`). This attribute is not supported in `MODULE.bazel` context (when invoking a repository rule inside a module extension's implementation function).	Dictionary: String -> String	optional
rust_toolchain_cargo_template	The template to use for finding the host `cargo` binary. `{version}` (eg. ‘1.53.0’), `{triple}` (eg. ‘x86_64-unknown-linux-gnu’), `{arch}` (eg. ‘aarch64’), `{vendor}` (eg. ‘unknown’), `{system}` (eg. ‘darwin’), `{cfg}` (eg. ‘exec’), `{channel}` (eg. ‘stable’), and `{tool}` (eg. ‘rustc.exe’) will be replaced in the string if present.	String	optional	`"@rust_{system}_{arch}__{triple}__{channel}_tools//:bin/{tool}"`
rust_toolchain_rustc_template	The template to use for finding the host `rustc` binary. `{version}` (eg. ‘1.53.0’), `{triple}` (eg. ‘x86_64-unknown-linux-gnu’), `{arch}` (eg. ‘aarch64’), `{vendor}` (eg. ‘unknown’), `{system}` (eg. ‘darwin’), `{cfg}` (eg. ‘exec’), `{channel}` (eg. ‘stable’), and `{tool}` (eg. ‘cargo.exe’) will be replaced in the string if present.	String	optional	`"@rust_{system}_{arch}__{triple}__{channel}_tools//:bin/{tool}"`
rust_version	The version of Rust the currently registered toolchain is using. Eg. `1.56.0`, or `nightly/2021-09-08`	String	optional	`"1.80.0"`
splicing_config	The configuration flags to use for splicing Cargo maniests. Use `//crate_universe:defs.bzl\%rsplicing_config` to generate the value for this field. If unset, the defaults defined there will be used.	String	optional	`""`
supported_platform_triples	A set of all platform triples to consider when generating dependencies.	List of strings	optional	["aarch64-unknown-linux-gnu", "aarch64-unknown-nixos-gnu", "i686-apple-darwin", "i686-pc-windows-msvc", "i686-unknown-linux-gnu", "x86_64-apple-darwin", "x86_64-pc-windows-msvc", "x86_64-unknown-linux-gnu", "x86_64-unknown-nixos-gnu", "aarch64-apple-darwin", "aarch64-apple-ios-sim", "aarch64-apple-ios", "aarch64-fuchsia", "aarch64-linux-android", "aarch64-pc-windows-msvc", "arm-unknown-linux-gnueabi", "armv7-linux-androideabi", "armv7-unknown-linux-gnueabi", "i686-linux-android", "i686-unknown-freebsd", "powerpc-unknown-linux-gnu", "riscv32imc-unknown-none-elf", "riscv64gc-unknown-none-elf", "s390x-unknown-linux-gnu", "thumbv7em-none-eabi", "thumbv8m.main-none-eabi", "wasm32-unknown-unknown", "wasm32-wasi", "x86_64-apple-ios", "x86_64-fuchsia", "x86_64-linux-android", "x86_64-unknown-freebsd", "x86_64-unknown-none", "aarch64-unknown-nto-qnx710"]

ENVIRONMENT VARIABLES

This repository rule depends on the following environment variables:

CARGO_BAZEL_GENERATOR_URL
CARGO_BAZEL_GENERATOR_SHA256
CARGO_BAZEL_REPIN
REPIN
CARGO_BAZEL_REPIN_ONLY
CARGO_BAZEL_ISOLATED
CARGO_BAZEL_DEBUG