Use the Bundler shipped with that Ruby by default

* Fixes #358

Author: eregon

README.md

@@ -155,9 +155,12 @@ should be able to fix them by setting `rubygems: 3.0.0` or higher.
 
 ### Bundler
 
-By default, if there is a `Gemfile.lock` file (or `$BUNDLE_GEMFILE.lock` or `gems.locked`) with a `BUNDLED WITH` section,
-that version of Bundler will be installed and used.
-Otherwise, the latest compatible Bundler version is installed (Bundler 2 on Ruby >= 2.4, Bundler 1 on Ruby < 2.4).
+By default, Bundler is installed as follows:
+
+* If there is a `Gemfile.lock` file (or `$BUNDLE_GEMFILE.lock` or `gems.locked`) with a `BUNDLED WITH` section,
+  that version of Bundler will be installed and used.
+* If the Ruby ships with Bundler (as a default gem), that version is used.
+* Otherwise, the latest compatible Bundler version is installed (Bundler 2 on Ruby >= 2.4, Bundler 1 on Ruby < 2.4).
 
 This behavior can be customized, see [action.yml](action.yml) for more details about the `bundler` input.
 

action.yml

@@ -16,9 +16,11 @@ inputs:
       Similarly, if a version number is given, `gem update --system <version>` is run to update to that version of RubyGems, as long as that version is newer than the one provided by default.
   bundler:
     description: |
-      The version of Bundler to install. Either 'none', 'latest', 'Gemfile.lock', or a version number (e.g., 1, 2, 2.1, 2.1.4).
-      For 'Gemfile.lock', the version is determined based on the BUNDLED WITH section from the file Gemfile.lock, $BUNDLE_GEMFILE.lock or gems.locked.
-      Defaults to 'default', which means 'Gemfile.lock' if the file exists and 'latest' otherwise.
+      The version of Bundler to install. Either 'Gemfile.lock' (the default), 'default', 'latest', 'none', or a version number (e.g., 1, 2, 2.1, 2.1.4).
+      For 'Gemfile.lock', the version of the BUNDLED WITH section from the Gemfile.lock if it exists. If the file or section does not exist then the same as 'default'.
+      For 'default', the version of Bundler that comes with that Ruby by default is used, or if that Ruby comes without Bundler then the same as 'latest'.
+      For 'latest', the latest compatible Bundler version is installed (Bundler 2 on Ruby >= 2.4, Bundler 1 on Ruby < 2.4).
+      For 'none', nothing is done.
   bundler-cache:
     description: 'Run "bundle install", and cache the result automatically. Either true or false.'
     default: 'false'

bundler.js

@@ -53,15 +53,29 @@ async function afterLockFile(lockFile, platform, engine, rubyVersion) {
 export async function installBundler(bundlerVersionInput, rubygemsInputSet, lockFile, platform, rubyPrefix, engine, rubyVersion) {
   let bundlerVersion = bundlerVersionInput
 
-  if (rubygemsInputSet && bundlerVersion === 'default') {
+  if (rubygemsInputSet && (bundlerVersion === 'default' || bundlerVersion === 'Gemfile.lock')) {
     console.log('Using the Bundler installed by updating RubyGems')
     return 'unknown'
   }
 
-  if (bundlerVersion === 'default' || bundlerVersion === 'Gemfile.lock') {
-    bundlerVersion = readBundledWithFromGemfileLock(lockFile)
+  if (bundlerVersion === 'Gemfile.lock') {
+    let bundlerVersionFromGemfileLock = readBundledWithFromGemfileLock(lockFile)
 
-    if (!bundlerVersion) {
+    if (bundlerVersionFromGemfileLock) {
+      bundlerVersion = bundlerVersionFromGemfileLock
+    } else {
+      bundlerVersion = 'default'
+    }
+  }
+
+  if (bundlerVersion === 'default') {
+    if (common.isBundler2Default(engine, rubyVersion)) {
+      console.log(`Using Bundler 2 shipped with ${engine}-${rubyVersion}`)
+      return '2'
+    } else if (common.isBundler1Default(engine, rubyVersion)) {
+      console.log(`Using Bundler 1 shipped with ${engine}-${rubyVersion}`)
+      return '1'
+    } else {
       bundlerVersion = 'latest'
     }
   }
@@ -92,30 +106,14 @@ export async function installBundler(bundlerVersionInput, rubygemsInputSet, lock
     }
   }
 
-  // Workaround for truffleruby 22.0 + latest Bundler, use shipped Bundler instead: https://github.com/oracle/truffleruby/issues/2586
-  const truffleruby22workaround = engine.startsWith('truffleruby') && rubyVersion.startsWith('22.0')
-  const useShippedBundler2 = common.isHeadVersion(rubyVersion) || truffleruby22workaround
+  const gem = path.join(rubyPrefix, 'bin', 'gem')
+  // Workaround for https://github.com/rubygems/rubygems/issues/5245
+  const force = (platform.startsWith('windows-') && engine === 'ruby' && floatVersion >= 3.1) ? ['--force'] : []
 
-  if (useShippedBundler2 && common.isBundler2Default(engine, rubyVersion) && bundlerVersion.startsWith('2')) {
-    // Avoid installing a newer Bundler version for head versions as it might not work.
-    // For releases, even if they ship with Bundler 2 we install the latest Bundler.
-    if (truffleruby22workaround) {
-      console.log(`Using Bundler 2 shipped with ${engine}-${rubyVersion} (workaround for https://github.com/oracle/truffleruby/issues/2586 on truffleruby 22.0)`)
-    } else {
-      console.log(`Using Bundler 2 shipped with ${engine}-${rubyVersion} (head versions do not always support the latest Bundler release)`)
-    }
-  } else if (engine.startsWith('truffleruby') && common.isBundler1Default(engine, rubyVersion) && bundlerVersion.startsWith('1')) {
-    console.log(`Using Bundler 1 shipped with ${engine}-${rubyVersion} (required for truffleruby < 21.0)`)
-  } else {
-    const gem = path.join(rubyPrefix, 'bin', 'gem')
-    // Workaround for https://github.com/rubygems/rubygems/issues/5245
-    const force = (platform.startsWith('windows-') && engine === 'ruby' && floatVersion >= 3.1) ? ['--force'] : []
+  const versionParts = [...bundlerVersion.matchAll(/\d+/g)].length
+  const bundlerVersionConstraint = versionParts === 3 ? bundlerVersion : `~> ${bundlerVersion}.0`
 
-    const versionParts = [...bundlerVersion.matchAll(/\d+/g)].length
-    const bundlerVersionConstraint = versionParts === 3 ? bundlerVersion : `~> ${bundlerVersion}.0`
-
-    await exec.exec(gem, ['install', 'bundler', ...force, '-v', bundlerVersionConstraint])
-  }
+  await exec.exec(gem, ['install', 'bundler', ...force, '-v', bundlerVersionConstraint])
 
   return bundlerVersion
 }

common.js

@@ -56,7 +56,15 @@ export function isStableVersion(rubyVersion) {
 }
 
 export function isBundler1Default(engine, rubyVersion) {
-  return !isBundler2Default(engine, rubyVersion)
+  if (engine === 'ruby') {
+    return floatVersion(rubyVersion) >= 2.6 && floatVersion(rubyVersion) < 2.7
+  } else if (engine.startsWith('truffleruby')) {
+    return floatVersion(rubyVersion) < 21.0
+  } else if (engine === 'jruby') {
+    return false
+  } else {
+    return false
+  }
 }
 
 export function isBundler2Default(engine, rubyVersion) {

dist/index.js

@@ -12,7 +12,7 @@ const windows = common.windows
 const inputDefaults = {
   'ruby-version': 'default',
   'rubygems': 'default',
-  'bundler': 'default',
+  'bundler': 'Gemfile.lock',
   'bundler-cache': 'false',
   'working-directory': '.',
   'cache-version': bundler.DEFAULT_CACHE_VERSION,