In cases where Rust targets have heavy interactions with other Bazel targets (Cc, Proto, etc.), maintaining Cargo.toml files may have diminishing returns as things like rust-analyzer begin to be confused about missing targets or environment variables defined only in Bazel. In situations like this, it may be desirable to have a “Cargo free” setup. crates_repository supports this through the packages attribute.
To build the example code, run:
bazel build //...
To declare Rust crate dependencies directly, add them to your MODULE file as shown below:
crate = use_extension("@rules_rust//crate_universe:extension.bzl", "crate")
#
# External crates
crate.spec(package = "arc-swap", version = "1.7")
crate.spec(package = "serde", features = ["derive"], version = "1.0")
crate.spec(package = "serde_json", version = "1.0")
crate.spec(package = "tokio", default_features=False, features = ["macros", "net", "rt-multi-thread", "signal"], version = "1.38")
crate.spec(package = "tokio-cron-scheduler", features = ["signal"], version = "0.10")
crate.spec(package = "warp", version = "0.3")
crate.from_specs()
use_repo(crate, "crates")Consuming dependencies may be more ergonomic in this case through the aliases defined in the new repository. In your BUILD files, you use direct dependencies as shown below:
rust_binary(
name = "bin",
crate_root = "src/main.rs",
srcs = glob([
"src/*.rs",
]),
deps = [
# External crates
# External crates
"@crates//:arc-swap",
"@crates//:serde",
"@crates//:serde_json",
"@crates//:tokio",
"@crates//:tokio-cron-scheduler",
"@crates//:warp",
],
visibility = ["//visibility:public"],
)Notice, direct dependencies do not need repining. Only a cargo workspace needs updating whenever the underlying Cargo.toml file changed.
Build with debug symbols:
bazel build //...
Build with optimization:
bazel build -c opt //...
And run the optimized binary:
bazel run -c opt //rest_tokio:bin