cargo-semver-checks-action

Lint your crate API changes for semver violations.

- name: Check semver
  uses: obi1kenobi/cargo-semver-checks-action@v2
- name: Publish to crates.io
  run: # your `cargo publish` code here

• Basic usage
• Input options
• Example scenarios
  • Use outside root directory of a crate or a workspace
  • Specify crates to be checked
  • Exclude crates from being checked
  • Use toolchain other than stable
  • Build for target other than default
• Customizing baseline rustdoc caching strategy

Basic usage

The action is designed to be used right before cargo publish. It will check the API of your crate for semver violations, comparing it to the latest normal (not pre-release or yanked) version published on crates.io. At the moment, the action does not support checking against other baselines, such as the destination branch of a pull request.

If your repository is just a crate or a workspace, the action will work out-of-the-box with sensible defaults:

semver-checks:
  runs-on: ubuntu-latest
  steps:
    - name: Checkout
      uses: actions/checkout@v4
    - name: Check semver
      uses: obi1kenobi/cargo-semver-checks-action@v2

Note By default, the action always installs the latest stable Rust and ignores the rust-toolchain.toml file and any local overrides. This ensures we use the latest version of rustdoc, taking advantage of the latest bugfixes and avoiding false-positives. If you want to change this default behavior, see Use toolchain other than stable.

Input options

Every argument is optional.

Input	Description	Default
package	Comma-separated list of the packages whose API to check for semver (in Package Id Specification format, see https://doc.rust-lang.org/cargo/reference/pkgid-spec.html for reference). If not set, all packages defined in the Cargo.toml file are processed.
exclude	Comma-separated list of the packages that will be excluded from being processed. Has effect only if the input package is not specified.
manifest-path	Path to Cargo.toml of crate or workspace to check. If not specified, the action assumes the manifest is under the default GITHUB_WORKSPACE path.
feature-group	Which feature group to enable. When not set, the action heuristically enables all features that are not unstable, nightly, or internal-only. Possible values: all-features, default-features, only-explicit-features.
features	Explicitly enable a list of features when checking. Corresponds to the tool's --features flag.
verbose	Enables verbose output of cargo-semver-checks.	false
release-type	Sets the release type instead of deriving it from the version number specified in the Cargo.toml file. Possible values are major, minor, patch.
rust-toolchain	Rust toolchain name to use, e.g. stable, nightly or 1.68.0. It will be installed if necessary and used regardless of local overrides and the rust-toolchain.toml file. However, if the input is set to manual, the action assumes some Rust toolchain is already installed and uses the default one.	stable
rust-target	Rust target to build for, e.g. x86_64-pc-windows-msvc or aarch64-apple-darwin. It will be installed if necessary and used regardless of the .cargo/config.toml file. However, if rust-toolchain is set to manual, the action assumes the target is already installed.
shared-key	A cache key that will be used instead of the automatic key based on the name of the GitHub job and values of the inputs package, exclude and manifest-path. Might be provided e.g. to share the cache between the jobs.
prefix-key	Additional prefix of the cache key, can be set to start a new cache manually.
github-token	The GITHUB_TOKEN secret used to download precompiled binaries from GitHub API. If not specified, the automatic GitHub token provided to the workflow will be used. The token may be alternatively passed in an environment variable GITHUB_TOKEN.	${{ github.token }}

Example scenarios

Use outside root directory of a crate or a workspace

The action will work well with defaults settings if it is run inside the package root directory. When the package location is different, you have to specify the path to its Cargo.toml file:

- name: Check semver for my-crate
  uses: obi1kenobi/cargo-semver-checks-action@v2
  with:
    manifest-path: semver/my-crate/Cargo.toml  # or just semver/my-crate/

In the same way you can provide the path to the workspace Cargo.toml file, which will result in checking all its crates:

- name: Check semver for all crates from my-workspace
  uses: obi1kenobi/cargo-semver-checks-action@v2
  with:
    manifest-path: semver/my-workspace/Cargo.toml  # or just semver/my-workspace/

Specify crates to be checked

By default, all packages defined in the Cargo.toml file are processed. You can specify one or more packages to be checked instead using input package.

For example, this will check my-crate-api and my-crate-core:

- name: Check semver for my-crate-api and my-crate-core
  uses: obi1kenobi/cargo-semver-checks-action@v2
  with:
    package: my-crate-api, my-crate-core

Inputs package and manifest-path might be used together:

- name: Check semver for my-crate from my-workspace
  uses: obi1kenobi/cargo-semver-checks-action@v2
  with:
    manifest-path: semver/my-workspace/Cargo.toml  # or just semver/my-workspace/
    package: my-crate

Exclude crates from being checked

This will process all crates from the current workspace except my-crate-tests:

- name: Check semver for all crates except my-crate-tests
  uses: obi1kenobi/cargo-semver-checks-action@v2
  with:
    exclude: my-crate-tests

Use toolchain other than stable

By default, the action installs (if necessary) and then uses the stable toolchain regardless of local overrides and the rust-toolchain.toml file. You can force using a different toolchain using rust-toolchain:

- name: Check semver
  uses: obi1kenobi/cargo-semver-checks-action@v2
  with:
    rust-toolchain: nightly

If you want to setup the toolchain manually, you can set rust-toolchain to manual. In this case, the action assumes some Rust toolchain is already installed and uses the default one:

- name: Setup Rust
  uses: actions-rust-lang/setup-rust-toolchain@v1
  with:
    toolchain: stable
- name: Check semver
  uses: obi1kenobi/cargo-semver-checks-action@v2
  with:
    rust-toolchain: manual

Build for target other than default

By default, the action uses the default target based on the host platform. You can force using a different target (which will be installed if missing) using rust-target. For example, you can check an aarch64-apple-darwin build while using the default Linux-based GitHub Actions runner:

- name: Check semver
  uses: obi1kenobi/cargo-semver-checks-action@v2
  with:
    rust-target: aarch64-apple-darwin

If you want to set up the toolchain manually, you can set rust-toolchain to manual. In this case, the action will not attempt to install the target — instead, it assumes the target is already set up:

- name: Setup Rust
  uses: actions-rust-lang/setup-rust-toolchain@v1
  with:
    toolchain: stable
    target: aarch64-apple-darwin
- name: Check semver
  uses: obi1kenobi/cargo-semver-checks-action@v2
  with:
    rust-toolchain: manual
    rust-target: aarch64-apple-darwin

Customizing baseline rustdoc caching strategy

The action caches the baseline rustdoc for each package in the workspace. The keys used to distinguish the caches consist of four components:

• prefix-key input, which defaults to an empty string,
• shared-key input if provided, otherwise the value of environmental variable GITHUB_JOB concatenated with a hash of the values of inputs package, exclude and manifest-path (we hash the path itself, not the file it points to),
• internal, unchangable component, being a concatenation of the runner OS, rustc version, cargo-semver-checks version and hash of all Cargo.lock files in the current workspace,
• constant suffix "semver-checks-rustdoc".

Runs that differ in at least one of the above components will use separate caches. Inputs prefix-key and shared-key might be therefore used to customize the caching strategy. For example, the two following jobs will share the key even despite using different manifest-path:

semver:
  runs-on: ubuntu-latest
  steps:
    - name: Checkout
      uses: actions/checkout@v4
    - name: Check semver
      uses: obi1kenobi/cargo-semver-checks-action@v2
      with:
        shared-key: my-workspace-semver

semver2:
  runs-on: ubuntu-latest
  steps:
    - name: Checkout
      uses: actions/checkout@v4
      with:
        path: semver
    - name: Check semver
      uses: obi1kenobi/cargo-semver-checks-action@v2
      with:
        manifest-path: semver/Cargo.toml
        shared-key: my-workspace-semver

which is reasonable until they are checking the same packages. Runs with different targets must not share the cache! For example, the below job is doing well with default settings:

semver:
  runs-on: ubuntu-latest
  strategy:
    matrix:
      crate: ['api', 'core']
  steps:
    - name: Checkout
      uses: actions/checkout@v4
    - name: Check semver
      uses: obi1kenobi/cargo-semver-checks-action@v2
      with:
        package: ${{ matrix.crate }}
        # Do not do this!
        # shared-key: 'my-workspace-semver'

as both runs will use separate caches, but providing the shared key will lead to data race and significant drop of performance. On the other hand, if you want to further separate the caches that are shared by default, you can use the input prefix-key:

- name: Check semver
  uses: obi1kenobi/cargo-semver-checks-action@v2
  with:
    prefix-key: v1