Read Ruby version from Gemfile.lock

.github/workflows/test.yml

@@ -217,6 +217,18 @@ jobs:
         rubygems: 3.2.3
     - run: gem --version | grep -F "3.3.3"
 
+  testRubyVersionFromGemfile:
+    name: "Test RUBY VERSION from Gemfile.lock"
+    runs-on: ubuntu-latest
+    env:
+      BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/ruby-version.gemfile
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          ruby-version: gemfile
+      - run: ruby --version | grep -F "3.3.1"
+
   testUseBundlerFromRubyGemsUpdate:
     name: "Test rubygems: version uses the Bundler installed by the rubygems update"
     runs-on: ubuntu-latest

.ruby-version

@@ -1 +1 @@
-ruby-2.6.5
+ruby-3.3.1

.tool-versions

@@ -1,2 +1,3 @@
 nodejs 16.0.0
-ruby 2.7.0
+yarn 1.22.19
+ruby 3.3.1

README.md

@@ -20,7 +20,7 @@ This action currently supports these versions of MRI, JRuby and TruffleRuby:
 | `truffleruby` | 19.3.0 - 24.0.1, head |
 | `truffleruby+graalvm` | 21.2.0 - 24.0.1, head |
 
-`ruby-debug` is the same as `ruby-head` but with assertions enabled (`-DRUBY_DEBUG=1`).  
+`ruby-debug` is the same as `ruby-head` but with assertions enabled (`-DRUBY_DEBUG=1`).
 
 Regarding Windows ruby master builds, `mingw` is a MSYS2/MinGW build, `head` & `ucrt` are MSYS2/UCRT64
 builds, and `mswin` is a MSVC/VS 2022 build.
@@ -135,7 +135,8 @@ and the [condition and expression syntax](https://help.github.com/en/actions/ref
 * engine only like `ruby` and `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`
+* `gemfile` reads from the project's `Gemfile.lock` file
+* If the `ruby-version` input is not specified, `.ruby-version` is tried first, followed by `.tool-versions`, then `Gemfile.lock`.
 
 ### Working Directory
 
@@ -176,8 +177,8 @@ This action provides a way to automatically run `bundle install` and cache the r
 
 Note that any step doing `bundle install` (for the root `Gemfile`) or `gem install bundler` can be removed with `bundler-cache: true`.
 
-This caching speeds up installing gems significantly and avoids too many requests to RubyGems.org.  
-It needs a `Gemfile` (or `$BUNDLE_GEMFILE` or `gems.rb`) under the [`working-directory`](#working-directory).  
+This caching speeds up installing gems significantly and avoids too many requests to RubyGems.org.
+It needs a `Gemfile` (or `$BUNDLE_GEMFILE` or `gems.rb`) under the [`working-directory`](#working-directory).
 If there is a `Gemfile.lock` (or `$BUNDLE_GEMFILE.lock` or `gems.locked`), `bundle config --local deployment true` is used.
 
 To use a `Gemfile` which is not at the root or has a different name, set `BUNDLE_GEMFILE` in the `env` at the job level
@@ -191,7 +192,7 @@ They should be set in the `env` at the job level as shown in the [example](#matr
 To find the correct the environment variable name, see the [Bundler docs](https://bundler.io/man/bundle-config.1.html) or look at `.bundle/config` after running `bundle config --local KEY VALUE` locally.
 You might need to `"`-quote the environment variable name in YAML if it has unusual characters like `/`.
 
-To perform caching, this action will use `bundle config --local path $PWD/vendor/bundle`.  
+To perform caching, this action will use `bundle config --local path $PWD/vendor/bundle`.
 Therefore, the Bundler `path` should not be changed in your workflow for the cache to work (no `bundle config path`).
 
 #### How it Works

action.yml

@@ -6,7 +6,7 @@ branding:
   icon: download
 inputs:
   ruby-version:
-    description: 'Engine and version to use, see the syntax in the README. Reads from .ruby-version or .tool-versions if unset.'
+    description: 'Engine and version to use, see the syntax in the README. Reads from .ruby-version, .tool-versions or Gemfile.lock.'
     default: 'default'
   rubygems:
     description: |

gemfiles/ruby-version.gemfile

@@ -0,0 +1,3 @@
+source 'https://rubygems.org'
+
+ruby "3.3.1"

gemfiles/ruby-version.gemfile.lock

@@ -0,0 +1,15 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+
+PLATFORMS
+  arm64-darwin-23
+  ruby
+
+DEPENDENCIES
+
+RUBY VERSION
+   ruby 3.3.1p55
+
+BUNDLED WITH
+   2.5.9

index.js

@@ -105,14 +105,29 @@ export async function setupRuby(options = {}) {
   core.setOutput('ruby-prefix', rubyPrefix)
 }
 
+function readRubyVersionFromGemfileLock(lockFile) {
+  if (lockFile !== null && fs.existsSync(lockFile)) {
+    const contents = fs.readFileSync(lockFile, 'utf8')
+    const lines = contents.split(/\r?\n/)
+    const rubyVersionLine = lines.findIndex(line => /^RUBY VERSION$/.test(line.trim()))
+    if (rubyVersionLine !== -1) {
+      const nextLine = lines[rubyVersionLine+1].trim().replace(/p\d+$/, '') // Strip off patchlevel because ruby-builder can't be that precise
+      return nextLine
+    }
+  }
+  return null
+}
+
 function parseRubyEngineAndVersion(rubyVersion) {
   if (rubyVersion === 'default') {
     if (fs.existsSync('.ruby-version')) {
       rubyVersion = '.ruby-version'
     } else if (fs.existsSync('.tool-versions')) {
       rubyVersion = '.tool-versions'
+    } else if (fs.existsSync('Gemfile.lock')) {
+      rubyVersion = 'gemfile'
     } else {
-      throw new Error('input ruby-version needs to be specified if no .ruby-version or .tool-versions file exists')
+      throw new Error('input ruby-version needs to be specified if no .ruby-version, .tool-versions or Gemfile.lock file exists')
     }
   }
 
@@ -124,19 +139,29 @@ function parseRubyEngineAndVersion(rubyVersion) {
     const rubyLine = toolVersions.split(/\r?\n/).filter(e => /^ruby\s/.test(e))[0]
     rubyVersion = rubyLine.match(/^ruby\s+(.+)$/)[1]
     console.log(`Using ${rubyVersion} as input from file .tool-versions`)
+  } else if (rubyVersion === 'gemfile') { // Read from Gemfile.lock
+    rubyVersion = readRubyVersionFromGemfileLock('Gemfile.lock')
+    if (rubyVersion === null) {
+      throw new Error('Could not find Ruby version in Gemfile.lock')
+    }
+    console.log(`Using ${rubyVersion} as input from Gemfile.lock`)
   }
 
   let engine, version
   if (/^(\d+)/.test(rubyVersion) || common.isHeadVersion(rubyVersion)) { // X.Y.Z => ruby-X.Y.Z
     engine = 'ruby'
     version = rubyVersion
+  } else if (rubyVersion.includes(' ')) { // engine X.Y.Z
+    [engine, version] = common.partition(rubyVersion, ' ')
   } else if (!rubyVersion.includes('-')) { // myruby -> myruby-stableVersion
     engine = rubyVersion
     version = '' // Let the logic in validateRubyEngineAndVersion() find the version
   } else { // engine-X.Y.Z
     [engine, version] = common.partition(rubyVersion, '-')
   }
 
+  console.log(`Using ruby engine ${engine} and version ${version}`)
+
   return [engine, version]
 }