fix: select musl JDK artifacts on Alpine for five distributions (#1220)

On Alpine, `getPlatformOption()` returned the glibc platform key for
Dragonwell, Corretto, Zulu, Liberica and Liberica NIK, so the action
resolved and installed a glibc JDK that cannot run under musl.

Add a shared `isAlpineLinux()` helper and use it to select each vendor's
musl artifacts:

| distribution | glibc         | musl           |
| ------------ | ------------- | -------------- |
| Dragonwell   | `linux`       | `alpine-linux` |
| Corretto     | `linux`       | `alpine`       |
| Zulu         | `linux_glibc` | `linux_musl`   |
| Liberica     | `linux`       | `linux-musl`   |
| Liberica NIK | `linux`       | `linux-musl`   |

Each key was verified against the vendor's live metadata API or manifest.

There is deliberately no silent fallback to glibc when a vendor has no
musl build for the requested version or architecture: the existing "could
not find a version that satisfies" error fires instead. This matches the
behaviour Temurin and SapMachine already have, and a glibc JDK would not
run on musl anyway.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 74248bb0-72af-41d8-b85d-b0f5836e68db

src/distributions/corretto/installer.ts

@@ -18,6 +18,7 @@ import {
   ICorrettoAllAvailableVersions,
   ICorrettoAvailableVersions
 } from './models.js';
+import {isAlpineLinux} from '../platform-types.js';
 
 const CORRETTO_VERSIONS_URL =
   'https://corretto.github.io/corretto-downloads/latest_links/indexmap_with_checksum.json';
@@ -189,6 +190,8 @@ export class CorrettoDistribution extends JavaBase {
         return 'macos';
       case 'win32':
         return 'windows';
+      case 'linux':
+        return isAlpineLinux() ? 'alpine' : 'linux';
       default:
         return process.platform;
     }

src/distributions/dragonwell/installer.ts

@@ -15,6 +15,7 @@ import {
   renameWinArchive
 } from '../../util.js';
 import {IDragonwellVersions, IDragonwellAllVersions} from './models.js';
+import {isAlpineLinux} from '../platform-types.js';
 import {
   JavaDownloadRelease,
   JavaInstallerOptions,
@@ -202,6 +203,8 @@ export class DragonwellDistribution extends JavaBase {
     switch (process.platform) {
       case 'win32':
         return 'windows';
+      case 'linux':
+        return isAlpineLinux() ? 'alpine-linux' : 'linux';
       default:
         return process.platform;
     }

src/distributions/liberica-nik/installer.ts

@@ -14,6 +14,7 @@ import {
 } from '../../util.js';
 import * as core from '@actions/core';
 import {ArchitectureOptions, NikVersion, OsVersions} from './models.js';
+import {isAlpineLinux} from '../platform-types.js';
 import fs from 'fs';
 import path from 'path';
 
@@ -156,7 +157,7 @@ export class LibericaNikDistributions extends JavaBase {
       case 'cygwin':
         return 'windows';
       case 'linux':
-        return 'linux';
+        return isAlpineLinux(platform) ? 'linux-musl' : 'linux';
       default:
         throw new Error(
           `Platform '${platform}' is not supported. Supported platforms: ${supportedPlatform}`

src/distributions/liberica/installer.ts

@@ -14,6 +14,7 @@ import {
 } from '../../util.js';
 import * as core from '@actions/core';
 import {ArchitectureOptions, LibericaVersion, OsVersions} from './models.js';
+import {isAlpineLinux} from '../platform-types.js';
 import fs from 'fs';
 import path from 'path';
 
@@ -154,7 +155,7 @@ export class LibericaDistributions extends JavaBase {
       case 'cygwin':
         return 'windows';
       case 'linux':
-        return 'linux';
+        return isAlpineLinux(platform) ? 'linux-musl' : 'linux';
       case 'sunos':
         return 'solaris';
       default:

src/distributions/zulu/installer.ts

@@ -6,6 +6,7 @@ import semver from 'semver';
 
 import {JavaBase} from '../base-installer.js';
 import {IZuluPackageDetails, IZuluVersions} from './models.js';
+import {isAlpineLinux} from '../platform-types.js';
 import {
   cacheJdkDir,
   extractJdkFile,
@@ -239,9 +240,10 @@ export class ZuluDistribution extends JavaBase {
       case 'win32':
         return 'windows';
       case 'linux':
-        // The new Metadata API's "linux" value returns both glibc and musl packages;
-        // use "linux_glibc" to target only glibc, which is what standard runners use.
-        return 'linux_glibc';
+        // The new Metadata API's "linux" value returns both glibc and musl
+        // packages, so target the libc the runner actually has. A glibc JDK
+        // cannot run on Alpine.
+        return isAlpineLinux() ? 'linux_musl' : 'linux_glibc';
       default:
         return process.platform;
     }