Add support for optional architecture input for cross-architecture .NET installs (#700)

* fix basic validation with npm command

* Revert "fix basic validation with npm command"

This reverts commit 27a0803a2a.

* add architecture support

* updated installdir logic

* update architecture resolution

* update normalizeArch

src/installer.ts

@@ -184,6 +184,16 @@ export class DotnetInstallScript {
     return this;
   }
 
+  // When architecture is empty/undefined, the installer auto-detects the current runner architecture.
+  public useArchitecture(architecture?: string) {
+    if (!architecture) return this;
+    this.useArguments(
+      IS_WINDOWS ? '-Architecture' : '--architecture',
+      architecture
+    );
+    return this;
+  }
+
   public useVersion(dotnetVersion: DotnetVersion, quality?: QualityOptions) {
     if (dotnetVersion.type) {
       this.useArguments(dotnetVersion.type, dotnetVersion.value);
@@ -250,6 +260,17 @@ export abstract class DotnetInstallDir {
   }
 }
 
+export function normalizeArch(arch: string): string {
+  switch (arch.toLowerCase()) {
+    case 'amd64':
+      return 'x64';
+    case 'ia32':
+      return 'x86';
+    default:
+      return arch.toLowerCase();
+  }
+}
+
 export class DotnetCoreInstaller {
   static {
     DotnetInstallDir.setEnvironmentVariable();
@@ -257,18 +278,30 @@ export class DotnetCoreInstaller {
 
   constructor(
     private version: string,
-    private quality: QualityOptions
+    private quality: QualityOptions,
+    private architecture?: string
   ) {}
 
   public async installDotnet(): Promise<string | null> {
     const versionResolver = new DotnetVersionResolver(this.version);
     const dotnetVersion = await versionResolver.createDotnetVersion();
 
+    const architectureArguments =
+      this.architecture &&
+      normalizeArch(this.architecture) !== normalizeArch(os.arch())
+        ? [
+            IS_WINDOWS ? '-InstallDir' : '--install-dir',
+            IS_WINDOWS
+              ? `"${path.join(DotnetInstallDir.dirPath, this.architecture)}"`
+              : path.join(DotnetInstallDir.dirPath, this.architecture)
+          ]
+        : [];
     /**
-     * Install dotnet runitme first in order to get
+     * Install dotnet runtime first in order to get
      * the latest stable version of dotnet CLI
      */
     const runtimeInstallOutput = await new DotnetInstallScript()
+      .useArchitecture(this.architecture)
       // If dotnet CLI is already installed - avoid overwriting it
       .useArguments(
         IS_WINDOWS ? '-SkipNonVersionedFiles' : '--skip-non-versioned-files'
@@ -277,6 +310,7 @@ export class DotnetCoreInstaller {
       .useArguments(IS_WINDOWS ? '-Runtime' : '--runtime', 'dotnet')
       // Use latest stable version
       .useArguments(IS_WINDOWS ? '-Channel' : '--channel', 'LTS')
+      .useArguments(...architectureArguments)
       .execute();
 
     if (runtimeInstallOutput.exitCode) {
@@ -294,12 +328,14 @@ export class DotnetCoreInstaller {
      * dotnet CLI
      */
     const dotnetInstallOutput = await new DotnetInstallScript()
+      .useArchitecture(this.architecture)
       // Don't overwrite CLI because it should be already installed
       .useArguments(
         IS_WINDOWS ? '-SkipNonVersionedFiles' : '--skip-non-versioned-files'
       )
       // Use version provided by user
       .useVersion(dotnetVersion, this.quality)
+      .useArguments(...architectureArguments)
       .execute();
 
     if (dotnetInstallOutput.exitCode) {

src/setup-dotnet.ts

@@ -1,9 +1,14 @@
 import * as core from '@actions/core';
 import * as exec from '@actions/exec';
-import {DotnetCoreInstaller, DotnetInstallDir} from './installer';
+import {
+  DotnetCoreInstaller,
+  DotnetInstallDir,
+  normalizeArch
+} from './installer';
 import * as fs from 'fs';
 import path from 'path';
 import semver from 'semver';
+import os from 'os';
 import * as auth from './authutil';
 import {isCacheFeatureAvailable} from './cache-utils';
 import {restoreCache} from './cache-restore';
@@ -17,6 +22,17 @@ const qualityOptions = [
   'preview',
   'ga'
 ] as const;
+const supportedArchitectures = [
+  'x64',
+  'x86',
+  'arm64',
+  'amd64',
+  'arm',
+  's390x',
+  'ppc64le',
+  'riscv64'
+] as const;
+type SupportedArchitecture = (typeof supportedArchitectures)[number];
 
 export type QualityOptions = (typeof qualityOptions)[number];
 
@@ -33,6 +49,7 @@ export async function run() {
     //
     const versions = core.getMultilineInput('dotnet-version');
     const installedDotnetVersions: (string | null)[] = [];
+    const architecture = getArchitectureInput();
 
     const globalJsonFileInput = core.getInput('global-json-file');
     if (globalJsonFileInput) {
@@ -70,10 +87,23 @@ export async function run() {
       let dotnetInstaller: DotnetCoreInstaller;
       const uniqueVersions = new Set<string>(versions);
       for (const version of uniqueVersions) {
-        dotnetInstaller = new DotnetCoreInstaller(version, quality);
+        dotnetInstaller = new DotnetCoreInstaller(
+          version,
+          quality,
+          architecture
+        );
         const installedVersion = await dotnetInstaller.installDotnet();
         installedDotnetVersions.push(installedVersion);
       }
+      if (
+        architecture &&
+        normalizeArch(architecture) !== normalizeArch(os.arch())
+      ) {
+        process.env['DOTNET_INSTALL_DIR'] = path.join(
+          DotnetInstallDir.dirPath,
+          architecture
+        );
+      }
       DotnetInstallDir.addToPath();
 
       const workloadsInput = core.getInput('workloads');
@@ -119,6 +149,20 @@ export async function run() {
   }
 }
 
+function getArchitectureInput(): SupportedArchitecture | '' {
+  const raw = (core.getInput('architecture') || '').trim();
+  if (!raw) return '';
+  const normalized = raw.toLowerCase();
+  if ((supportedArchitectures as readonly string[]).includes(normalized)) {
+    return normalizeArch(normalized) as SupportedArchitecture;
+  }
+  throw new Error(
+    `Value '${raw}' is not supported for the 'architecture' option. Supported values are: ${supportedArchitectures.join(
+      ', '
+    )}.`
+  );
+}
+
 function getVersionFromGlobalJson(globalJsonPath: string): string {
   let version = '';
   const globalJson = JSON5.parse(