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An action to download a prebuilt Ruby and add it to the PATH in 5 seconds
JavaScript Ruby
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Latest commit cdeaf53 Feb 16, 2020


Note: this action used to be at eregon/use-ruby-action and was moved to the ruby organization.

This action downloads a prebuilt ruby and adds it to the PATH.

It is very efficient and takes about 5 seconds to download, extract and add the given Ruby to the PATH. No extra packages need to be installed.

Compared to actions/setup-ruby, this actions supports many more versions and features.

Supported Versions

This action currently supports these versions of MRI, JRuby and TruffleRuby:

Interpreter Versions
Ruby 2.2, 2.3.0 - 2.3.8, 2.4.0 - 2.4.9, 2.5.0 - 2.5.7, 2.6.0 - 2.6.5, 2.7.0, head
JRuby, head
TruffleRuby 19.3.0, 19.3.1, head
Rubinius 4.14

Note that Ruby ≤ 2.3 and the OpenSSL version it needs (1.0.2) are both end-of-life, which means Ruby ≤ 2.3 is unmaintained and considered insecure. On Windows, Ruby 2.4 uses OpenSSL 1.0.2, which is no longer maintained. Ruby 2.2 resolves to 2.2.6 on Windows (last build from RubyInstaller) and 2.2.10 otherwise.

Supported Platforms

The action works for all GitHub-hosted runners.

Operating System Versions
Ubuntu ubuntu-latest (= ubuntu-18.04), ubuntu-16.04
macOS macos-latest
Windows windows-latest

Rubinius is only available on ubuntu-latest.

The prebuilt releases are generated by ruby-builder and on Windows by RubyInstaller2. ruby-head is generated by ruby-dev-builder and truffleruby-head is generated by truffleruby-dev-builder. The full list of available Ruby versions can be seen in ruby-builder-versions.js for Ubuntu and macOS and in windows-versions.js for Windows.


Single Job

name: My workflow
on: [push]
    runs-on: ubuntu-latest
    - uses: actions/checkout@v2
    - uses: ruby/setup-ruby@v1
        ruby-version: 2.6
    - run: ruby -v


This matrix tests all stable releases of MRI, JRuby and TruffleRuby on Ubuntu and macOS.

name: My workflow
on: [push]
      fail-fast: false
        os: [ ubuntu-latest, macos-latest ]
        ruby: [ 2.4, 2.5, 2.6, 2.7, jruby, truffleruby ]
    runs-on: ${{ matrix.os }}
    - uses: actions/checkout@v2
    - uses: ruby/setup-ruby@v1
        ruby-version: ${{ matrix.ruby }}
    - run: ruby -v

Supported Version Syntax

  • engine-version like ruby-2.6.5 and truffleruby-19.3.0

  • short version like 2.6, automatically using the latest release matching that version (2.6.5)

  • version only like 2.6.5, assumes MRI for the engine

  • engine only like truffleruby, uses the latest stable release of that implementation

  • .ruby-version reads from the project's .ruby-version file

  • .tool-versions reads from the project's .tool-versions file

  • If the ruby-version input is not specified, .ruby-version is tried first, followed by .tool-versions


Currently, Bundler is guaranteed to be installed for all versions. If the Ruby ships with Bundler (Ruby >= 2.6), that version is used. Otherwise (Ruby < 2.6), Bundler 1 is installed when that Ruby was built.

Caching bundle install

You can cache the installed gems with these two steps:

    - uses: actions/cache@v1
        path: vendor/bundle
        key: bundle-use-ruby-${{ matrix.os }}-${{ matrix.ruby }}-${{ hashFiles('**/Gemfile.lock') }}
        restore-keys: |
          bundle-use-ruby-${{ matrix.os }}-${{ matrix.ruby }}-
    - name: bundle install
      run: |
        bundle config path vendor/bundle
        bundle install --jobs 4 --retry 3

When using a single job with a Ruby version, replace ${{ matrix.ruby }} with the Ruby version.
When using .ruby-version, replace ${{ matrix.ruby }} with ${{ hashFiles('.ruby-version') }}.
When using .tool-versions, replace ${{ matrix.ruby }} with ${{ hashFiles('.tool-versions') }}.

This uses the cache action. The code above is a more complete version of the Ruby - Bundler example. Make sure to include use-ruby in the key to avoid conflicting with previous caches.


Note that running CI on Windows can be quite challenging if you are not very familiar with Windows. It is recommended to first get your build working on Ubuntu and macOS before trying Windows.

  • The default shell on Windows is not Bash but PowerShell. This can lead issues such as multi-line scripts not working as expected.
  • The PATH contains multiple compiler toolchains. Use where.exe to debug which tool is used.
  • MSYS2 is prepended to the PATH, similar to what RubyInstaller2 does.
  • JRuby on Windows has a known bug that bundle exec rake fails.


  • This action currently only works with GitHub-hosted runners, not private runners.


This action follows semantic versioning with a moving v1 branch. This follows the recommendations of GitHub Actions.


The current maintainer of this action is @eregon. Most of the Windows logic is from by MSP-Greg. Many thanks to MSP-Greg and Lars Kanis for the help with Ruby Installer.

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