Switch JAVA_HOME to 21 for JRuby

common.js

@@ -6,6 +6,7 @@ const stream = require('stream')
 const crypto = require('crypto')
 const core = require('@actions/core')
 const tc = require('@actions/tool-cache')
+const exec = require('@actions/exec')
 const { performance } = require('perf_hooks')
 const linuxOSInfo = require('linux-os-info')
 
@@ -403,3 +404,35 @@ export function setupPath(newPathEntries) {
   core.addPath(newPath.join(path.delimiter))
   return msys2Type
 }
+
+export async function setupJavaHome() {
+  core.startGroup(`Modifying JAVA_HOME for JRuby`)
+
+  console.log("attempting to run with existing JAVA_HOME")
+
+  let ret = await exec.exec('ruby', ['--version'])
+
+  if (ret === 0) {
+    console.log("JRuby successfully starts, using existing JAVA_HOME")
+  } else {
+    console.log("JRuby failed to start, try Java 21 envs")
+
+    let arch = os.arch();
+    if (arch === "x64" || os.platform() !== "darwin") {
+      arch = "X64"
+    }
+
+    let newHomeVar = `JAVA_HOME_21_${arch}`
+    let newHome = process.env[newHomeVar]
+
+    if (newHome === "undefined") {
+      throw new Error(`JAVA_HOME is not Java 21+ needed for JRuby and \$${newHomeVar} is not defined`)
+    }
+
+    console.log(`Setting JAVA_HOME to ${newHomeVar} path ${newHome}`)
+
+    core.exportVariable("JAVA_HOME", newHome)
+  }
+
+  core.endGroup()
+}

index.js

@@ -79,6 +79,10 @@ export async function setupRuby(options = {}) {
 
   const rubyPrefix = await installer.install(platform, engine, version)
 
+  if (engine === "jruby") {
+    await common.setupJavaHome()
+  }
+
   await common.measure('Print Ruby version', async () =>
     await exec.exec('ruby', ['--version']))