Bump actions/checkout from 4 to 5 (#631)

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 5.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v4...v5)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,7 +7,7 @@ assignees: ''
 
 ---
 
-<!--- Please direct any generic questions related to actions to our support community forum at https://github.community/c/code-to-cloud/github-actions/41 --->
+<!--- Please direct any generic questions related to actions to our support community forum at https://github.com/orgs/community/discussions/categories/actions --->
 <!--- Before opening up a new bug report, please make sure to check for similar existing issues -->
 
 **Description:**

.github/ISSUE_TEMPLATE/feature_request.md

@@ -5,7 +5,7 @@ title: ''
 labels: feature request, needs triage
 assignees: ''
 ---
-<!--- Please direct any generic questions related to actions to our support community forum at https://github.community/c/code-to-cloud/github-actions/41 --->
+<!--- Please direct any generic questions related to actions to our support community forum at https://github.com/orgs/community/discussions/categories/actions --->
 <!--- Before opening up a new feature request, please make sure to check for similar existing issues and pull requests -->
 
 **Description:**

.github/workflows/basic-validation.yml

@@ -15,4 +15,4 @@ jobs:
     name: Basic validation
     uses: actions/reusable-workflows/.github/workflows/basic-validation.yml@main
     with:
-      node-version: '20'
+      node-version: '24.x'

.github/workflows/check-dist.yml

@@ -16,4 +16,4 @@ jobs:
     name: Check dist/
     uses: actions/reusable-workflows/.github/workflows/check-dist.yml@main
     with:
-      node-version: '20'
+      node-version: '24.x'

.github/workflows/publish-immutable-actions.yml

@@ -14,7 +14,7 @@ jobs:
 
     steps:
       - name: Checking out
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
       - name: Publish
         id: publish
         uses: actions/publish-immutable-action@v0.0.4

.github/workflows/versions.yml

@@ -20,7 +20,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest, macos-13]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Setup Go Stable
         uses: ./
         with:
@@ -35,7 +35,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest, macos-13]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Setup Go oldStable
         uses: ./
         with:
@@ -57,7 +57,7 @@ jobs:
           - os: macos-13
             architecture: x32
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Setup Go ${{ matrix.version }} ${{ matrix.architecture }}
         uses: ./
         with:
@@ -82,7 +82,7 @@ jobs:
             go: 1.23.2
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: setup-go ${{ matrix.go }}
         uses: ./
@@ -101,7 +101,7 @@ jobs:
         os: [ubuntu-latest, windows-latest, macos-latest, macos-13]
         go-version: ['1.20', '1.21', '1.22', '1.23']
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Setup Go and check latest
         uses: ./
         with:
@@ -117,7 +117,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest, macos-13]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Setup Go and check latest
         uses: ./
         with:
@@ -133,7 +133,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest, macos-13]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Setup Go and check latest
         uses: ./
         with:
@@ -151,7 +151,7 @@ jobs:
         go: [1.20.14, 1.21.10, 1.22.8, 1.23.2]
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: setup-go ${{ matrix.go }}
         uses: ./
@@ -171,7 +171,7 @@ jobs:
         go: [1.11.12]
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: setup-go ${{ matrix.go }}
         uses: ./
@@ -199,7 +199,7 @@ jobs:
           - os: macos-13
             architecture: x64
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Setup Go and check latest
         uses: ./
         with:

.github/workflows/windows-validation.yml

@@ -19,7 +19,7 @@ jobs:
         cache: [false, true]
         go: [1.20.1]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: 'Setup ${{ matrix.cache }}, cache: ${{ matrix.go }}'
         uses: ./
@@ -88,7 +88,7 @@ jobs:
       matrix:
         cache: [false, true]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: 'Setup default go, cache: ${{ matrix.cache }}'
         uses: ./
@@ -121,7 +121,7 @@ jobs:
         cache: [false]
         go: [1.20.1]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: 'Setup ${{ matrix.go }}, cache: ${{ matrix.cache }}'
         uses: ./

README.md

@@ -50,8 +50,8 @@ Matching by [semver spec](https://github.com/npm/node-semver):
 
 ```yaml
 steps:
-  - uses: actions/checkout@v4
-  - uses: actions/setup-go@v5
+  - uses: actions/checkout@v5
+  - uses: actions/setup-go@v6
     with:
       go-version: '^1.13.1' # The Go version to download (if necessary) and use.
   - run: go version
@@ -59,8 +59,8 @@ steps:
 
 ```yaml
 steps:
-  - uses: actions/checkout@v4
-  - uses: actions/setup-go@v5
+  - uses: actions/checkout@v5
+  - uses: actions/setup-go@v6
     with:
       go-version: '>=1.17.0'
   - run: go version
@@ -78,8 +78,8 @@ Matching an unstable pre-release:
 
 ```yaml
 steps:
-  - uses: actions/checkout@v4
-  - uses: actions/setup-go@v5
+  - uses: actions/checkout@v5
+  - uses: actions/setup-go@v6
     with:
       go-version: '1.18.0-rc.1' # The Go version to download (if necessary) and use.
   - run: go version
@@ -87,8 +87,8 @@ steps:
 
 ```yaml
 steps:
-  - uses: actions/checkout@v4
-  - uses: actions/setup-go@v5
+  - uses: actions/checkout@v5
+  - uses: actions/setup-go@v6
     with:
       go-version: '1.16.0-beta.1' # The Go version to download (if necessary) and use.
   - run: go version
@@ -102,8 +102,8 @@ See [action.yml](action.yml)
 
 ```yaml
 steps:
-  - uses: actions/checkout@v4
-  - uses: actions/setup-go@v5
+  - uses: actions/checkout@v5
+  - uses: actions/setup-go@v6
     with:
       go-version: '1.16.1' # The Go version to download (if necessary) and use.
   - run: go run hello.go
@@ -123,8 +123,8 @@ want the most up-to-date Go version to always be used.
 
 ```yaml
 steps:
-  - uses: actions/checkout@v4
-  - uses: actions/setup-go@v5
+  - uses: actions/checkout@v5
+  - uses: actions/setup-go@v6
     with:
       go-version: '1.14'
       check-latest: true
@@ -144,8 +144,8 @@ set to `true`
 
 ```yaml
 steps:
-  - uses: actions/checkout@v4
-  - uses: actions/setup-go@v5
+  - uses: actions/checkout@v5
+  - uses: actions/setup-go@v6
     with:
       go-version: 'stable'
   - run: go run hello.go
@@ -153,8 +153,8 @@ steps:
 
 ```yaml
 steps:
-  - uses: actions/checkout@v4
-  - uses: actions/setup-go@v5
+  - uses: actions/checkout@v5
+  - uses: actions/setup-go@v6
     with:
       go-version: 'oldstable'
   - run: go run hello.go
@@ -176,8 +176,8 @@ If some problem that prevents success caching happens then the action issues the
 
 ```yaml
 steps:
-  - uses: actions/checkout@v4
-  - uses: actions/setup-go@v5
+  - uses: actions/checkout@v5
+  - uses: actions/setup-go@v6
     with:
       go-version: '1.17'
       check-latest: true
@@ -191,9 +191,15 @@ steps:
 
 ## Getting go version from the go.mod file
 
-The `go-version-file` input accepts a path to a `go.mod` file or a `go.work` file that contains the version of Go to be used by a project.
+The `go-version-file` input accepts a path to a `go.mod` file or a `go.work`
+file that contains the version of Go to be used by a project. The version taken
+from thils file will be:
+
+  - The version from the `toolchain` directive, if there is one, otherwise
+  - The version from the `go` directive
+
+The version can specify a patch version or omit it altogether (e.g., `go 1.22.0` or `go 1.22`).
 
-The `go` directive in `go.mod` can specify a patch version or omit it altogether (e.g., `go 1.22.0` or `go 1.22`).  
 If a patch version is specified, that specific patch version will be used.  
 If no patch version is specified, it will search for the latest available patch version in the cache,
 [versions-manifest.json](https://github.com/actions/go-versions/blob/main/versions-manifest.json), and the
@@ -204,8 +210,8 @@ If both the `go-version` and the `go-version-file` inputs are provided then the
 
 ```yaml
 steps:
-  - uses: actions/checkout@v4
-  - uses: actions/setup-go@v5
+  - uses: actions/checkout@v5
+  - uses: actions/setup-go@v6
     with:
       go-version-file: 'path/to/go.mod'
   - run: go version
@@ -222,9 +228,9 @@ jobs:
         go: [ '1.14', '1.13' ]
     name: Go ${{ matrix.go }} sample
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Setup go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version: ${{ matrix.go }}
       - run: go run hello.go
@@ -252,7 +258,7 @@ If that fails as well the action will try to download versions directly from htt
 If that fails as well you can get a higher rate limit with [generating a personal access token on github.com](https://github.com/settings/tokens/new) and passing it as the `token` input to the action:
 
 ```yaml
-uses: actions/setup-go@v5
+uses: actions/setup-go@v6
 with:
   token: ${{ secrets.GH_DOTCOM_TOKEN }}
   go-version: '1.18'

__tests__/setup-go.test.ts

@@ -129,6 +129,9 @@ describe('setup-go', () => {
   });
 
   afterEach(() => {
+    // clear out env var set during 'run'
+    delete process.env[im.GOTOOLCHAIN_ENV_VAR];
+
     //jest.resetAllMocks();
     jest.clearAllMocks();
     //jest.restoreAllMocks();
@@ -285,7 +288,7 @@ describe('setup-go', () => {
     expect(logSpy).toHaveBeenCalledWith(`Setup go version spec 1.13.0`);
   });
 
-  it('does not export any variables for Go versions >=1.9', async () => {
+  it('does not export GOROOT for Go versions >=1.9', async () => {
     inputs['go-version'] = '1.13.0';
     inSpy.mockImplementation(name => inputs[name]);
 
@@ -298,7 +301,7 @@ describe('setup-go', () => {
     });
 
     await main.run();
-    expect(vars).toStrictEqual({});
+    expect(vars).not.toHaveProperty('GOROOT');
   });
 
   it('exports GOROOT for Go versions <1.9', async () => {
@@ -314,9 +317,7 @@ describe('setup-go', () => {
     });
 
     await main.run();
-    expect(vars).toStrictEqual({
-      GOROOT: toolPath
-    });
+    expect(vars).toHaveProperty('GOROOT', toolPath);
   });
 
   it('finds a version of go already in the cache', async () => {
@@ -989,4 +990,104 @@ use .
       }
     );
   });
+
+  describe('go-version-file-toolchain', () => {
+    const goVersions = ['1.22.0', '1.21rc2', '1.18'];
+    const placeholderVersion = '1.19';
+    const buildGoMod = (
+      goVersion: string,
+      toolchainVersion: string
+    ) => `module example.com/mymodule
+
+go ${goVersion}
+
+toolchain go${toolchainVersion}
+
+require (
+	example.com/othermodule v1.2.3
+	example.com/thismodule v1.2.3
+	example.com/thatmodule v1.2.3
+)
+
+replace example.com/thatmodule => ../thatmodule
+exclude example.com/thismodule v1.3.0
+`;
+
+    const buildGoWork = (
+      goVersion: string,
+      toolchainVersion: string
+    ) => `go 1.19
+
+toolchain go${toolchainVersion}
+
+use .
+
+`;
+
+    goVersions.forEach(version => {
+      [
+        {
+          goVersionfile: 'go.mod',
+          fileContents: Buffer.from(buildGoMod(placeholderVersion, version)),
+          expected_version: version,
+          desc: 'from toolchain directive'
+        },
+        {
+          goVersionfile: 'go.work',
+          fileContents: Buffer.from(buildGoMod(placeholderVersion, version)),
+          expected_version: version,
+          desc: 'from toolchain directive'
+        },
+        {
+          goVersionfile: 'go.mod',
+          fileContents: Buffer.from(buildGoMod(placeholderVersion, version)),
+          gotoolchain_env: 'local',
+          expected_version: placeholderVersion,
+          desc: 'from go directive when GOTOOLCHAIN is local'
+        },
+        {
+          goVersionfile: 'go.work',
+          fileContents: Buffer.from(buildGoMod(placeholderVersion, version)),
+          gotoolchain_env: 'local',
+          expected_version: placeholderVersion,
+          desc: 'from go directive when GOTOOLCHAIN is local'
+        }
+      ].forEach(test => {
+        it(`reads version (${version}) in ${test.goVersionfile} ${test.desc}`, async () => {
+          inputs['go-version-file'] = test.goVersionfile;
+          if (test.gotoolchain_env !== undefined) {
+            process.env[im.GOTOOLCHAIN_ENV_VAR] = test.gotoolchain_env;
+          }
+          existsSpy.mockImplementation(() => true);
+          readFileSpy.mockImplementation(() => Buffer.from(test.fileContents));
+
+          await main.run();
+
+          expect(logSpy).toHaveBeenCalledWith(
+            `Setup go version spec ${test.expected_version}`
+          );
+          expect(logSpy).toHaveBeenCalledWith(
+            `Attempting to download ${test.expected_version}...`
+          );
+          expect(logSpy).toHaveBeenCalledWith(
+            `matching ${test.expected_version}...`
+          );
+        });
+      });
+    });
+  });
+
+  it('exports GOTOOLCHAIN and sets it in current process env', async () => {
+    inputs['go-version'] = '1.21.0';
+    inSpy.mockImplementation(name => inputs[name]);
+
+    const vars: {[key: string]: string} = {};
+    exportVarSpy.mockImplementation((name: string, val: string) => {
+      vars[name] = val;
+    });
+
+    await main.run();
+    expect(vars).toStrictEqual({GOTOOLCHAIN: 'local'});
+    expect(process.env).toHaveProperty('GOTOOLCHAIN', 'local');
+  });
 });

__tests__/utils.test.ts

@@ -0,0 +1,52 @@
+import {isSelfHosted} from '../src/utils';
+
+describe('utils', () => {
+  describe('isSelfHosted', () => {
+    let AGENT_ISSELFHOSTED: string | undefined;
+    let RUNNER_ENVIRONMENT: string | undefined;
+
+    beforeEach(() => {
+      AGENT_ISSELFHOSTED = process.env['AGENT_ISSELFHOSTED'];
+      delete process.env['AGENT_ISSELFHOSTED'];
+      RUNNER_ENVIRONMENT = process.env['RUNNER_ENVIRONMENT'];
+      delete process.env['RUNNER_ENVIRONMENT'];
+    });
+
+    afterEach(() => {
+      if (AGENT_ISSELFHOSTED === undefined) {
+        delete process.env['AGENT_ISSELFHOSTED'];
+      } else {
+        process.env['AGENT_ISSELFHOSTED'] = AGENT_ISSELFHOSTED;
+      }
+      if (RUNNER_ENVIRONMENT === undefined) {
+        delete process.env['RUNNER_ENVIRONMENT'];
+      } else {
+        process.env['RUNNER_ENVIRONMENT'] = RUNNER_ENVIRONMENT;
+      }
+    });
+
+    it('isSelfHosted should be true if no environment variables set', () => {
+      expect(isSelfHosted()).toBeTruthy();
+    });
+
+    it('isSelfHosted should be true if environment variable is not set to denote GitHub hosted', () => {
+      process.env['RUNNER_ENVIRONMENT'] = 'some';
+      expect(isSelfHosted()).toBeTruthy();
+    });
+
+    it('isSelfHosted should be true if environment variable set to denote Azure Pipelines self hosted', () => {
+      process.env['AGENT_ISSELFHOSTED'] = '1';
+      expect(isSelfHosted()).toBeTruthy();
+    });
+
+    it('isSelfHosted should be false if environment variable set to denote GitHub hosted', () => {
+      process.env['RUNNER_ENVIRONMENT'] = 'github-hosted';
+      expect(isSelfHosted()).toBeFalsy();
+    });
+
+    it('isSelfHosted should be false if environment variable is not set to denote Azure Pipelines self hosted', () => {
+      process.env['AGENT_ISSELFHOSTED'] = 'some';
+      expect(isSelfHosted()).toBeFalsy();
+    });
+  });
+});

package.json

@@ -1,9 +1,12 @@
 {
   "name": "setup-go",
-  "version": "5.0.0",
+  "version": "6.0.0",
   "private": true,
   "description": "setup go action",
   "main": "lib/setup-go.js",
+  "engines": {
+    "node": ">=24.0.0"
+  },
   "scripts": {
     "build": "tsc && ncc build -o dist/setup src/setup-go.ts && ncc build -o dist/cache-save src/cache-save.ts",
     "format": "prettier --no-error-on-unmatched-pattern --config ./.prettierrc.js --write \"**/*.{ts,yml,yaml}\"",
@@ -25,31 +28,31 @@
   "author": "GitHub",
   "license": "MIT",
   "dependencies": {
-    "@actions/cache": "^4.0.0",
-    "@actions/core": "^1.10.0",
-    "@actions/exec": "^1.1.0",
-    "@actions/glob": "^0.4.0",
+    "@actions/cache": "^4.0.3",
+    "@actions/core": "^1.11.1",
+    "@actions/exec": "^1.1.1",
+    "@actions/glob": "^0.5.0",
     "@actions/http-client": "^2.2.1",
     "@actions/io": "^1.0.2",
-    "@actions/tool-cache": "^2.0.1",
-    "semver": "^7.6.0"
+    "@actions/tool-cache": "^2.0.2",
+    "semver": "^7.6.3"
   },
   "devDependencies": {
-    "@types/jest": "^29.5.12",
-    "@types/node": "^20.11.28",
+    "@types/jest": "^29.5.14",
+    "@types/node": "^24.1.0",
     "@types/semver": "^7.5.8",
-    "@typescript-eslint/eslint-plugin": "^5.54.0",
-    "@typescript-eslint/parser": "^5.54.0",
+    "@typescript-eslint/eslint-plugin": "^8.31.1",
+    "@typescript-eslint/parser": "^8.35.1",
     "@vercel/ncc": "^0.38.1",
     "eslint": "^8.57.0",
-    "eslint-config-prettier": "^8.6.0",
-    "eslint-plugin-jest": "^27.9.0",
+    "eslint-config-prettier": "^10.0.1",
+    "eslint-plugin-jest": "^29.0.1",
     "eslint-plugin-node": "^11.1.0",
     "jest": "^29.7.0",
     "jest-circus": "^29.7.0",
     "nock": "^10.0.6",
     "prettier": "^2.8.4",
-    "ts-jest": "^29.1.2",
-    "typescript": "^5.4.2"
+    "ts-jest": "^29.3.2",
+    "typescript": "^5.8.3"
   }
 }

src/installer.ts

@@ -6,8 +6,11 @@ import * as httpm from '@actions/http-client';
 import * as sys from './system';
 import fs from 'fs';
 import os from 'os';
-import {StableReleaseAlias} from './utils';
+import {StableReleaseAlias, isSelfHosted} from './utils';
+import {Architecture} from './types';
 
+export const GOTOOLCHAIN_ENV_VAR = 'GOTOOLCHAIN';
+export const GOTOOLCHAIN_LOCAL_VAL = 'local';
 const MANIFEST_REPO_OWNER = 'actions';
 const MANIFEST_REPO_NAME = 'go-versions';
 const MANIFEST_REPO_BRANCH = 'main';
@@ -39,7 +42,7 @@ export async function getGo(
   versionSpec: string,
   checkLatest: boolean,
   auth: string | undefined,
-  arch = os.arch()
+  arch: Architecture = os.arch() as Architecture
 ) {
   let manifest: tc.IToolRelease[] | undefined;
   const osPlat: string = os.platform();
@@ -151,7 +154,7 @@ async function resolveVersionFromManifest(
   versionSpec: string,
   stable: boolean,
   auth: string | undefined,
-  arch: string,
+  arch: Architecture,
   manifest: tc.IToolRelease[] | undefined
 ): Promise<string | undefined> {
   try {
@@ -180,11 +183,7 @@ async function cacheWindowsDir(
   if (os.platform() !== 'win32') return false;
 
   // make sure the action runs in the hosted environment
-  if (
-    process.env['RUNNER_ENVIRONMENT'] !== 'github-hosted' &&
-    process.env['AGENT_ISSELFHOSTED'] === '1'
-  )
-    return false;
+  if (isSelfHosted()) return false;
 
   const defaultToolCacheRoot = process.env['RUNNER_TOOL_CACHE'];
   if (!defaultToolCacheRoot) return false;
@@ -279,11 +278,46 @@ export async function extractGoArchive(archivePath: string): Promise<string> {
   return extPath;
 }
 
+function isIToolRelease(obj: any): obj is tc.IToolRelease {
+  return (
+    typeof obj === 'object' &&
+    obj !== null &&
+    typeof obj.version === 'string' &&
+    typeof obj.stable === 'boolean' &&
+    Array.isArray(obj.files) &&
+    obj.files.every(
+      (file: any) =>
+        typeof file.filename === 'string' &&
+        typeof file.platform === 'string' &&
+        typeof file.arch === 'string' &&
+        typeof file.download_url === 'string'
+    )
+  );
+}
+
 export async function getManifest(
   auth: string | undefined
 ): Promise<tc.IToolRelease[]> {
   try {
-    return await getManifestFromRepo(auth);
+    const manifest = await getManifestFromRepo(auth);
+    if (
+      Array.isArray(manifest) &&
+      manifest.length &&
+      manifest.every(isIToolRelease)
+    ) {
+      return manifest;
+    }
+
+    let errorMessage =
+      'An unexpected error occurred while fetching the manifest.';
+    if (
+      typeof manifest === 'object' &&
+      manifest !== null &&
+      'message' in manifest
+    ) {
+      errorMessage = (manifest as {message: string}).message;
+    }
+    throw new Error(errorMessage);
   } catch (err) {
     core.debug('Fetching the manifest via the API failed.');
     if (err instanceof Error) {
@@ -322,7 +356,7 @@ export async function getInfoFromManifest(
   versionSpec: string,
   stable: boolean,
   auth: string | undefined,
-  arch = os.arch(),
+  arch: Architecture = os.arch() as Architecture,
   manifest?: tc.IToolRelease[] | undefined
 ): Promise<IGoVersionInfo | null> {
   let info: IGoVersionInfo | null = null;
@@ -348,7 +382,7 @@ export async function getInfoFromManifest(
 
 async function getInfoFromDist(
   versionSpec: string,
-  arch: string
+  arch: Architecture
 ): Promise<IGoVersionInfo | null> {
   const version: IGoVersion | undefined = await findMatch(versionSpec, arch);
   if (!version) {
@@ -367,7 +401,7 @@ async function getInfoFromDist(
 
 export async function findMatch(
   versionSpec: string,
-  arch = os.arch()
+  arch: Architecture = os.arch() as Architecture
 ): Promise<IGoVersion | undefined> {
   const archFilter = sys.getArch(arch);
   const platFilter = sys.getPlatform();
@@ -464,14 +498,30 @@ export function parseGoVersionFile(versionFilePath: string): string {
     path.basename(versionFilePath) === 'go.mod' ||
     path.basename(versionFilePath) === 'go.work'
   ) {
-    const match = contents.match(/^go (\d+(\.\d+)*)/m);
-    return match ? match[1] : '';
+    // for backwards compatibility: use version from go directive if
+    // 'GOTOOLCHAIN' has been explicitly set
+    if (process.env[GOTOOLCHAIN_ENV_VAR] !== GOTOOLCHAIN_LOCAL_VAL) {
+      // toolchain directive: https://go.dev/ref/mod#go-mod-file-toolchain
+      const matchToolchain = contents.match(
+        /^toolchain go(1\.\d+(?:\.\d+|rc\d+)?)/m
+      );
+      if (matchToolchain) {
+        return matchToolchain[1];
+      }
+    }
+
+    // go directive: https://go.dev/ref/mod#go-mod-file-go
+    const matchGo = contents.match(/^go (\d+(\.\d+)*)/m);
+    return matchGo ? matchGo[1] : '';
   }
 
   return contents.trim();
 }
 
-async function resolveStableVersionDist(versionSpec: string, arch: string) {
+async function resolveStableVersionDist(
+  versionSpec: string,
+  arch: Architecture
+) {
   const archFilter = sys.getArch(arch);
   const platFilter = sys.getPlatform();
   const dlUrl = 'https://golang.org/dl/?mode=json&include=all';

src/main.ts

@@ -8,6 +8,7 @@ import {isCacheFeatureAvailable} from './cache-utils';
 import cp from 'child_process';
 import fs from 'fs';
 import os from 'os';
+import {Architecture} from './types';
 
 export async function run() {
   try {
@@ -16,14 +17,15 @@ export async function run() {
     // If not supplied then problem matchers will still be setup.  Useful for self-hosted.
     //
     const versionSpec = resolveVersionInput();
+    setGoToolchain();
 
     const cache = core.getBooleanInput('cache');
     core.info(`Setup go version spec ${versionSpec}`);
 
-    let arch = core.getInput('architecture');
+    let arch = core.getInput('architecture') as Architecture;
 
     if (!arch) {
-      arch = os.arch();
+      arch = os.arch() as Architecture;
     }
 
     if (versionSpec) {
@@ -160,3 +162,20 @@ function resolveVersionInput(): string {
 
   return version;
 }
+
+function setGoToolchain() {
+  // docs: https://go.dev/doc/toolchain
+  // "local indicates the bundled Go toolchain (the one that shipped with the go command being run)"
+  // this is so any 'go' command is run with the selected Go version
+  // and doesn't trigger a toolchain download and run commands with that
+  // see e.g. issue #424
+  // and a similar discussion: https://github.com/docker-library/golang/issues/472.
+  // Set the value in process env so any `go` commands run as child-process
+  // don't cause toolchain downloads
+  process.env[installer.GOTOOLCHAIN_ENV_VAR] = installer.GOTOOLCHAIN_LOCAL_VAL;
+  // and in the runner env so e.g. a user running `go mod tidy` won't cause it
+  core.exportVariable(
+    installer.GOTOOLCHAIN_ENV_VAR,
+    installer.GOTOOLCHAIN_LOCAL_VAL
+  );
+}

src/system.ts

@@ -1,4 +1,5 @@
 import os from 'os';
+import {Architecture} from './types';
 
 export function getPlatform(): string {
   // darwin and linux match already
@@ -15,7 +16,7 @@ export function getPlatform(): string {
   return plat;
 }
 
-export function getArch(arch: string): string {
+export function getArch(arch: Architecture): string {
   // 'arm', 'arm64', 'ia32', 'mips', 'mipsel', 'ppc', 'ppc64', 's390', 's390x', 'x32', and 'x64'.
 
   // wants amd64, 386, arm64, armv61, ppc641e, s390x

src/types.ts

@@ -0,0 +1,2 @@
+// match what @actions/tool-cache expects
+export type Architecture = string;

src/utils.ts

@@ -2,3 +2,13 @@ export enum StableReleaseAlias {
   Stable = 'stable',
   OldStable = 'oldstable'
 }
+
+export const isSelfHosted = (): boolean =>
+  process.env['RUNNER_ENVIRONMENT'] !== 'github-hosted' &&
+  (process.env['AGENT_ISSELFHOSTED'] === '1' ||
+    process.env['AGENT_ISSELFHOSTED'] === undefined);
+/* the above is simplified from:
+    process.env['RUNNER_ENVIRONMENT'] !== 'github-hosted' && process.env['AGENT_ISSELFHOSTED'] === '1'
+    ||
+    process.env['RUNNER_ENVIRONMENT'] !== 'github-hosted' && process.env['AGENT_ISSELFHOSTED'] === undefined
+*/