Setup Rust and Cargo

A one-stop-shop GitHub action for setting up Rust and Cargo. Will automatically setup the Rust toolchain with rustup, cache the ~/.cargo/registry and /target/debug directories, and install Cargo binaries (when applicable).

jobs:
  ci:
    name: CI
    runs-on: ubuntu-latest
    steps:
      # ...
      - uses: moonrepo/setup-rust@v1
      - run: cargo test

Inputs

The following inputs are available for the action, and can be passed via with. All inputs are optional.

• bins - Comma-separated list of global binaries to install into Cargo.
• cache - Toggle caching of directories. Defaults to true.
• cache-base - Base branch/ref to save a warmup cache on. Other branches/refs will restore from this base.
• cache-target - Name of the target profile to cache. Defaults to debug.
• channel - Toolchain specification/channel to explicitly install.
• components - Comma-separated list of additional components to install.
• inherit-toolchain - Inherit all toolchain settings from the rust-toolchain.toml file. Defaults to false.
• targets - Comma-separated list of additional targets to install.
• profile - Profile to install. Defaults to minimal.

Configuring the Rust toolchain

This action will automatically install the appropriate toolchain with rustup by inspecting the RUSTUP_TOOLCHAIN environment variable or the rust-toolchain.toml (preferred) or rust-toolchain configuration files. If no toolchain found, will default to stable.

# rust-toolchain.toml
[toolchain]
channel = "1.68.0"

When loading a configuration file, only the channel field is used, while the other fields are ignored. We chose this approach, as those other fields are typically for develop/release workflows, but not for CI, which requires a minimal/granular setup. However, this can be overwritten with the inherit-toolchain input.

The toolchain/channel can also be explicitly configured with the channel input, which takes highest precedence.

- uses: moonrepo/setup-rust@v1
  with:
    channel: '1.65.0'

Profile, components, and targets

Furthermore, this action supports rustup profiles, components, and targets, which can be configured with the profile, components, and targets inputs respectively. When not defined, profile defaults to minimal.

- uses: moonrepo/setup-rust@v1
  with:
    profile: complete

When using components, the input requires a comma separated list of component names.

- uses: moonrepo/setup-rust@v1
  with:
    components: clippy
- run: cargo clippy --workspace

When using targets, the input requires a comma separated list of target triples.

- uses: moonrepo/setup-rust@v1
  with:
    targets: 'x86_64-pc-windows-msvc,x86_64-pc-windows-gnu'

Installing Cargo binaries

If you require cargo-make, cargo-nextest, or other global binaries, this action supports installing Cargo binaries through the bins input, which requires a comma-separated list of crate names.

- uses: moonrepo/setup-rust@v1
  with:
    bins: cargo-nextest, [email protected]
  env:
    GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

Binaries are installed with cargo-binstall under the hood. We suggest setting GITHUB_TOKEN to avoid rate limiting.

Caching in CI

By default this action will cache the ~/.cargo/registry and /target/debug directories to improve CI times. To disable caching, set the cache input to false. Furthermore, the target profile can be changed with the cache-target input, which defaults to debug.

- uses: moonrepo/setup-rust@v1
  with:
    cache: false
    cache-target: release

The following optimizations and considerations are taken into account when caching:

• ~/.cargo
  • The /bin directory is not cached as we manage binary installation in this action via the bins input.
  • The /git directory is not cached as it's not necessary for CI. When required by Cargo or a crate, a checkout will be performed on-demand.
  • The /registry directory is cleaned before saving the cache. This includes removing src, .cache, and any other unnecessary files.
• /target
  • Only the /debug profile is cached, as this profile is typically used for formatting, linting, and testing. This can be changed with the cache-target input.
  • The /examples and /incremental sub-directories are not cached as they are not necessary for CI.
  • All dep-info (*.d) files are removed, as they're meant for build systems and signaling re-executions.

The following sources are hashed for the generated cache key: $GITHUB_JOB, Cargo.lock, Rust version, Rust commit hash, and OS.

Warmup strategy

Another strategy that we support is called a warmup cache, where a base branch/ref is used to generate and save the cache (like master), and all other branches/refs will only restore this cache (and not save).

This can be enabled with the cache-base input, which requires a branch/ref name. This input also supports regex.

- uses: moonrepo/setup-rust@v1
  with:
    cache-base: master
    # With regex
    cache-base: (master|main|develop)

Compared to

actions-rs/*

The "official" actions have served their purpose, but after 3 years of no updates, severe lack of maintenance, and being full of deprecation warnings, it was time to create something new.

Outside of being evergreen, this action also supports the following features:

• Automatically caches.
• Installs Cargo bins.
• Assumes rustup, cargo, and other commands are available globally. This allows you to use them directly in a run command, without having to use actions-rs/cargo.

dtolnay/rust-toolchain

Our action is very similar to theirs, which was a great implementation reference, but our action also supports the following features:

• Extracts the toolchain/channel from rust-toolchain.toml and rust-toolchain configuration files.
• Automatically caches.
• Installs Cargo bins.

Swatinem/rust-cache

Their action only caches for Rust/Cargo, it doesn't actually setup Rust/Cargo. Our action is meant to do everything, but it's not as configurable as the alternatives.

Here are the key differences between the two:

• Theirs caches the entire ~/.cargo directory, while our action only caches ~/.cargo/registry. View the reasoning above.
  • Our action also avoids an array of ~/.cargo/bin issues that theirs currently has.
• Theirs includes compiler specific environment variables in the cache key, while our action currently does not.
• Theirs supports a handful of inputs for controlling the cache key, while ours does not.
• Theirs is a bit more smart in what it caches, while ours is a bit more brute force. We simply cache specific directories as-is after cleaning.