cargo-raze 0.0.12

A Cargo subcommand to generate BUILD files for pre-vendored dependencies
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cargo raze

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A cargo subcommand to generate platform-specific BUILD files.

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

Caution: Under Development!

This is still under heavy development. It has few tests and is very unstable. 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, include the rust rules:

git_repository(
    name = "io_bazel_rules_rust",
    commit = "5b94fdb",
    remote = "https://github.com/acmcarther/rules_rust.git",
)
load("@io_bazel_rules_rust//rust:repositories.bzl", "rust_repositories")

rust_repositories()

Create a Cargo.toml containing the crates you want to include and configuration for raze:

[package]
name = "compile_with_bazel"
version = "0.1.0"

[dependencies]
log = "0.3.6"

[raze]
workspace_path = "//label/for/vendored/crates" # The WORKSPACE relative path to the Cargo.toml working directory. 
target = "x86_64-unknown-linux-gnu" # The target to generate BUILD rules for.

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

cargo install cargo-vendor
cargo install cargo-raze
cargo generate-lockfile
cargo vendor -x
cargo raze

Your dependencies each get a shiny new BUILD file that bazel can use to link your dependencies up.

See my hobby project space_coop for a real life example, with its raze Cargo.toml here.

Additional Configuration

Sometimes it's necessary to change the way a crate is built, generally to provide a native library or provide configuration.

See these examples of providing crate configuration:

TODO:

  • Proper platform detection. Currently we take platform as a configuration parameter. This isn't too hard, just haven't had time.
  • Platform-agnostic generated BUILD. 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.