Automatically find the latest stable version

.github/workflows/test.yml

@@ -6,7 +6,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ 'ubuntu-16.04', 'ubuntu-18.04', 'macos-latest' ]
-        ruby: [ 'ruby-2.6.5', 'ruby-2.7.0', 'truffleruby-19.3.0', 'jruby-9.2.9.0' ]
+        ruby: [ 'ruby-2.6.5', '2.7.0', 'truffleruby', 'jruby-9.2.9.0' ]
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2

README.md

@@ -46,6 +46,10 @@ jobs:
     - run: ruby -v
 ```
 
+If a specific version is not given, it uses the latest stable release of that implementation.
+
+For instance `truffleruby` is currently the same as `truffleruby-19.3.0`.
+
 ## Efficiency
 
 It takes about 5 seconds to setup the given Ruby.

index.js

@@ -1,16 +1,24 @@
+const os = require('os')
+const fs = require('fs')
 const core = require('@actions/core')
 const io = require('@actions/io')
 const tc = require('@actions/tool-cache')
-const os = require('os')
-const fs = require('fs')
+const axios = require('axios')
 
 async function run() {
   try {
     const rubyVersion = core.getInput('ruby-version')
 
     let ruby = rubyVersion
-    if (!ruby.includes('-')) {
-      ruby = 'ruby-' + ruby;
+    if (ruby.match(/^\d+/)) { // X.Y.Z => ruby-X.Y.Z
+      ruby = 'ruby-' + ruby
+    }
+    if (!ruby.includes('-')) { // myruby -> myruby-stableVersion
+      const versionsUrl = 'https://raw.githubusercontent.com/eregon/ruby-install-builder/metadata/versions.json'
+      const response = await axios.get(versionsUrl)
+      const stableVersions = response.data[ruby]
+      const latestStableVersion = stableVersions[stableVersions.length-1]
+      ruby = ruby + '-' + latestStableVersion
     }
 
     const rubiesDir = `${process.env.HOME}/.rubies`

package-lock.json

@@ -122,6 +122,15 @@
       "integrity": "sha512-+Ryf6g3BKoRc7jfp7ad8tM4TtMiaWvbF/1/sQcZPkkS7ag3D5nMBCe2UfOTONtAkaG0tO0ij3C5Lwmf1EiyjHg==",
       "dev": true
     },
+    "axios": {
+      "version": "0.19.0",
+      "resolved": "https://registry.npmjs.org/axios/-/axios-0.19.0.tgz",
+      "integrity": "sha512-1uvKqKQta3KBxIz14F2v06AEHZ/dIoeKfbTRkK1E5oqjDnuEerLmYTgJB5AiQZHJcljpg1TuRzdjDR06qNk0DQ==",
+      "requires": {
+        "follow-redirects": "1.5.10",
+        "is-buffer": "^2.0.2"
+      }
+    },
     "balanced-match": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.0.tgz",
@@ -210,6 +219,14 @@
         "which": "^1.2.9"
       }
     },
+    "debug": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/debug/-/debug-3.1.0.tgz",
+      "integrity": "sha512-OX8XqP7/1a9cqkxYw2yXss15f26NKWBpDXQd0/uK/KPqdQhxbPa994hnzjcE2VqQpDslf55723cKPUOGSmMY3g==",
+      "requires": {
+        "ms": "2.0.0"
+      }
+    },
     "deep-is": {
       "version": "0.1.3",
       "resolved": "https://registry.npmjs.org/deep-is/-/deep-is-0.1.3.tgz",
@@ -454,6 +471,14 @@
       "integrity": "sha512-a1hQMktqW9Nmqr5aktAux3JMNqaucxGcjtjWnZLHX7yyPCmlSV3M54nGYbqT8K+0GhF3NBgmJCc3ma+WOgX8Jg==",
       "dev": true
     },
+    "follow-redirects": {
+      "version": "1.5.10",
+      "resolved": "https://registry.npmjs.org/follow-redirects/-/follow-redirects-1.5.10.tgz",
+      "integrity": "sha512-0V5l4Cizzvqt5D44aTXbFZz+FtyXV1vrDN6qrelxtfYQKW0KO0W2T/hkE8xvGa/540LkZlkaUjO4ailYTFtHVQ==",
+      "requires": {
+        "debug": "=3.1.0"
+      }
+    },
     "fs.realpath": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
@@ -606,6 +631,11 @@
         }
       }
     },
+    "is-buffer": {
+      "version": "2.0.4",
+      "resolved": "https://registry.npmjs.org/is-buffer/-/is-buffer-2.0.4.tgz",
+      "integrity": "sha512-Kq1rokWXOPXWuaMAqZiJW4XxsmD9zGx9q4aePabbn3qCRGedtH7Cm+zV8WETitMfu1wdh+Rvd6w5egwSngUX2A=="
+    },
     "is-extglob": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/is-extglob/-/is-extglob-2.1.1.tgz",
@@ -723,6 +753,11 @@
         }
       }
     },
+    "ms": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/ms/-/ms-2.0.0.tgz",
+      "integrity": "sha1-VgiurfwAvmwpAd9fmGF4jeDVl8g="
+    },
     "mute-stream": {
       "version": "0.0.7",
       "resolved": "https://registry.npmjs.org/mute-stream/-/mute-stream-0.0.7.tgz",

package.json

@@ -25,7 +25,8 @@
   "dependencies": {
     "@actions/core": "^1.1.1",
     "@actions/io": "^1.0.1",
-    "@actions/tool-cache": "^1.1.2"
+    "@actions/tool-cache": "^1.1.2",
+    "axios": "^0.19.0"
   },
   "devDependencies": {
     "@zeit/ncc": "^0.20.5",