rust-bazel-example

Automated builds are executed on each PR, and once a week even if no code changed the week prior.

This is an example starter project that uses bazel to compile rust programs.

I wanted to do this because I think bazel is useful for building project with many target types, and we should use it more.

One of the issues with bazel is that many rules have poor IDE integration. Rust rules are not one of those, which is nice. This example generates rust-project.json, which you can plug into the IDE of your choice, if your IDE supports the Language Server Protocol (LSP).

Try it out now

The below command should simply work. File a bug if it does not.

bazel run //program:my_program

Re-generate rust-project.json

You want to run the command below whenever your list of rust external dependencies changes. This command is documented at: https://bazelbuild.github.io/rules_rust/rust_analyzer.html

bazel run @rules_rust//tools/rust_analyzer:gen_rust_project

Re-generate lockfiles

You want to run the command below whenever your list of rust external dependencies changes.

env CARGO_BAZEL_REPIN=true bazel build //...

Where to go from here?

If you want to see more examples of rust use in Bazel, check out the rules_rust examples page at: https://github.com/bazelbuild/rules_rust/tree/main/examples

Things I did to make this happen

Here are the changes needed to make a minimal program that uses bazel to build a rust binary.

The instructions below were current at the time of this writing, which was on September 30, 2023. Previous versions of this repository used an older version of rules_rust, and the procedure to bring in upstream crates was quite different.

• Edited WORKSPACE file to:

  • include rules for building rust.
  • add a rule that makes bazel download remote rust repositories.
  • add a rule to download external rust crates.

• Made sure that target and rust-project.json are in .gitignore. This allows us to use regular cargo builds in rust only directories. This might come in handy.

• Ran the following, to generate rust-project.json in //:

  bazel run @rules_rust//tools/rust_analyzer:gen_rust_project
  

  This will enable you to use rust-analyzer as your language server for the project and all vendored crates.

Notes

• The files //:Cargo.Bazel.lock and //:Cargo.lock would probably better fit into a directory //third_party/cargo, but that does not seem to work.