rubyfmt-action

Run rubyfmt as a GitHub Actions PR check.

rubyfmt-action downloads a pinned, checksum-verified rubyfmt release and runs it with --check, so your job fails whenever a pull request introduces unformatted Ruby. No Ruby installation, gem, or Docker is required — the action just needs curl and tar, which are present on GitHub-hosted runners by default.

Quickstart

name: Ruby formatting

on:
  pull_request:
    branches: ["**"]

permissions:
  contents: read

jobs:
  rubyfmt:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2

      - name: Run rubyfmt
        uses: rubyatscale/rubyfmt-action@v1

If rubyfmt finds unformatted files, the job fails, the diff is printed to the log, and (by default) added to the job summary.

Inputs

paths

Default: .

paths is a whitespace-separated list of files and/or directories for rubyfmt to check.

- uses: rubyatscale/rubyfmt-action@v1
  with:
    paths: |
      app/
      lib/

version

Default: latest

The version of rubyfmt to use. This can be latest or an exact version, e.g. 0.14.2-10 (with or without a leading v). Only versions that have been pinned in support/versions are accepted; see Pinning a new version below.

fail-fast

Default: false

Whether rubyfmt should fail immediately on syntax/IO errors, instead of warning and continuing.

include-gitignored

Default: false

Whether to also check files that are excluded by .gitignore.

header-mode

Default: none

Controls rubyfmt's magic header comment behavior:

• none: check every input file (default)
• opt-in: only check files containing a # rubyfmt: true header
• opt-out: skip files containing a # rubyfmt: false header

summary

Default: true

Whether to write a diff of any unformatted files to the job summary ($GITHUB_STEP_SUMMARY).

Outputs

outcome

Either success or failure, matching whether rubyfmt found any unformatted files.

Supported runners

rubyfmt only publishes precompiled binaries for a subset of platforms, so this action supports:

• ubuntu-latest / other Linux x86_64 runners
• Linux aarch64 runners
• macos-latest / other Apple Silicon (arm64) runners

Intel Mac runners and Windows runners are not supported and will fail with a clear error.

Pinning a new version

This action only downloads rubyfmt releases whose checksums have been pinned in support/versions, to avoid trusting a release's contents sight-unseen at CI time. To pin a new release:

support/sync-versions.sh v0.15.0

This downloads each platform's release asset, records its checksum in support/versions, and marks the version as latest in support/latest. Pass --historical to pin an older release without changing what latest resolves to.

A self-hosted Renovate job runs weekly and opens a PR bumping support/latest when a new rubyfmt release is available, and similarly for the shellcheck version pinned in ci.yml. Neither of those PRs update the corresponding checksum(s) automatically (there's nothing for Renovate to safely fetch a checksum from), so CI on those PRs fails until the checksum is refreshed — run support/sync-versions.sh <tag> for rubyfmt, or manually recompute and update SHELLCHECK_SHA256 for shellcheck. Dependabot (see dependabot.yml) separately handles the rest of this repo's GitHub Actions dependencies.

License

This project is licensed under the MIT License. See LICENSE for the full licensing terms.