cargo raze

A cargo subcommand to generate platform-specific BUILD files.

Also, a bazel ruleset for using the outputs of that cargo subcommand.

See examples in the automatically updated examples repository: github.com/acmcarther/cargo-raze-examples

WARNING!!!

This is still under heavy development. It has few tests and is very unstable. Please do not use it in a production environment! It relies on some custom changes to the rules_rust library to support build scripts and duplicate crate definitions. The changes are available in the diff between my repo and master.

If you'd like to use it anyway, you are definitely welcome to. Please direct any questions to acmcarther@: your input would be very helpful to guide development

Problem

You like cargo's package rich ecosystem, but are interested in using Bazel to build a multilanguage, large, or otherwise complex set of applications.

So far you've either stuck with Cargo and made do with build.rs files, or migrated to Bazel and avoided crates.io dependencies or manually generated a select set of BUILD files for vendored dependencies.

cargo raze gives you the best of both worlds: rust library downloading + resolution courtesy of Cargo with the power and scalability of Bazel.

Getting Started

In your Bazel WORKSPACE:

git_repository(
    name = "io_bazel_rules_raze",
    remote = "https://github.com/acmcarther/cargo-raze.git",
    commit = "c84e361"
)

git_repository(
    name = "io_bazel_rules_rust",
    remote = "https://github.com/acmcarther/rules_rust.git",
    commit = "49a7345"
)
load("@io_bazel_rules_rust//rust:rust.bzl", "rust_repositories")

rust_repositories()

Then, in a directory containing 'Cargo.toml'. Project root is fine:

cargo install cargo-vendor
cargo install cargo-raze
cargo generate-lockfile
cargo vendor -x
cargo raze "//path/to/vendor"

You dependencies each get a shiny new Cargo.bzl file that bazel can use to link your dependencies up. You will also get starter BUILD files that reference those .bzl files.

See my hobby project space_coop for a real life example.

Project Structure

This repo is a hybrid cargo crate + Bazel Skylark ruleset. The project is structured roughly as follows:

cargo-raze crate:

• ./Cargo.toml
• ./Cargo.lock
• ./src/

rules_raze:

• ./WORKSPACE
• ./examples/
• ./raze/

TODO:

• Proper platform detection. Currently we just use generic linux. This isn't too hard, just haven't had time.
• Platform-agnostic generated Cargo.bzl. I envision mapping the existing platform-specific dependency support down to a handful of supported platforms within the bazel rule, rather than here. That lets us use bazel's select construct to support multiple platforms with a single rule.
• Clean up folder structure
• Set up dual compilation (compile raze via bazel OR via cargo). Prereq: openssl. Openssl is major pain to compile.