Bazel for Rust

Also checkout the FAQ for common issues and solutions.

TL;DR

• Commands:
  • sg bazel configure rustdeps after changing workspace members or dependencies.
    • Setting CARGO_BAZEL_ISOLATED=0 can be set if repinning is too slow, if doing it frequently in local development.
  • CARGO_BAZEL_REPIN=<crate name> sg bazel configure rustdeps after adding/updating a dependency.

Overview

The rules interfacing Rust are named rules_rust and they provide all the plumbing to call the Rust compiler and run the tests.

Bazel and Rust works slightly differently to Bazel and Go. Unlike with Go, BUILD.bazel files are not updated with sg bazel configure (they must be updated/configured/created by hand), and instead of there being one BUILD.bazel file per directory, it's one per workspace member. There exists gazelle_rust, a plugin for Gazelle which is invoked via sg bazel configure, that may address the first point but we have decided not to invest in using it at the time of writing.

Rules for Rust

The rules you'll see for Rust are rust_binary, rust_library, rust_test and rust_proc_macro.

Each rule type will have a certain set of common attribute values between them for dependency and proc-macro resolution, alongside others such as name and rule-specific attributes with values specific to those particular instances that are each briefly explained in the docs for the relevant rules, found at the links above.

rust_binary and rust_library targets have the following displayed attribute values in common:

aliases = aliases(),
proc_macro_deps = all_crate_deps(
  proc_macro = True,
),
deps = all_crate_deps(
  normal = True,
),

while rust_test targets have the following displayed attribute values in common:

aliases = aliases(
  normal_dev = True,
  proc_macro_dev = True,
),
proc_macro_deps = all_crate_deps(
  proc_macro_dev = True,
),
deps = all_crate_deps(
  normal_dev = True,
),