Merge branch 'actions:main' into restore-only

README.md

@@ -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

__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({
+    expect(vars).toHaveProperty('GOROOT', toolPath);
-      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');
+  });
 });

package-lock.json

@@ -207,12 +207,15 @@
       }
     },
     "node_modules/@azure/core-http/node_modules/form-data": {
-      "version": "4.0.0",
+      "version": "4.0.4",
-      "resolved": "https://registry.npmjs.org/form-data/-/form-data-4.0.0.tgz",
+      "resolved": "https://registry.npmjs.org/form-data/-/form-data-4.0.4.tgz",
-      "integrity": "sha512-ETEklSGi5t0QMZuiXoA/Q6vcnxcLQP5vdugSpuAyi6SVGi2clPPp+xgEhuMaHC+zGgn31Kd235W35f7Hykkaww==",
+      "integrity": "sha512-KrGhL9Q4zjj0kiUt5OO4Mr/A/jlI2jDYs5eHBpYHPcBEVSiipAvn2Ko2HnPe20rmcuuvMHNdZFp+4IlGTMF0Ow==",
+      "license": "MIT",
       "dependencies": {
         "asynckit": "^0.4.0",
         "combined-stream": "^1.0.8",
+        "es-set-tostringtag": "^2.1.0",
+        "hasown": "^2.0.2",
         "mime-types": "^2.1.12"
       },
       "engines": {
@@ -1613,12 +1616,15 @@
       }
     },
     "node_modules/@types/node-fetch/node_modules/form-data": {
-      "version": "4.0.0",
+      "version": "4.0.4",
-      "resolved": "https://registry.npmjs.org/form-data/-/form-data-4.0.0.tgz",
+      "resolved": "https://registry.npmjs.org/form-data/-/form-data-4.0.4.tgz",
-      "integrity": "sha512-ETEklSGi5t0QMZuiXoA/Q6vcnxcLQP5vdugSpuAyi6SVGi2clPPp+xgEhuMaHC+zGgn31Kd235W35f7Hykkaww==",
+      "integrity": "sha512-KrGhL9Q4zjj0kiUt5OO4Mr/A/jlI2jDYs5eHBpYHPcBEVSiipAvn2Ko2HnPe20rmcuuvMHNdZFp+4IlGTMF0Ow==",
+      "license": "MIT",
       "dependencies": {
         "asynckit": "^0.4.0",
         "combined-stream": "^1.0.8",
+        "es-set-tostringtag": "^2.1.0",
+        "hasown": "^2.0.2",
         "mime-types": "^2.1.12"
       },
       "engines": {
@@ -2409,6 +2415,19 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
+    "node_modules/call-bind-apply-helpers": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/call-bind-apply-helpers/-/call-bind-apply-helpers-1.0.2.tgz",
+      "integrity": "sha512-Sp1ablJ0ivDkSzjcaJdxEunN5/XvksFJ2sMBFfq6x0ryhQV/2b/KwFe21cMpmHtPOSij8K99/wSfoEuTObmuMQ==",
+      "license": "MIT",
+      "dependencies": {
+        "es-errors": "^1.3.0",
+        "function-bind": "^1.1.2"
+      },
+      "engines": {
+        "node": ">= 0.4"
+      }
+    },
     "node_modules/callsites": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/callsites/-/callsites-3.1.0.tgz",
@@ -2776,6 +2795,20 @@
         "node": ">=6.0.0"
       }
     },
+    "node_modules/dunder-proto": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/dunder-proto/-/dunder-proto-1.0.1.tgz",
+      "integrity": "sha512-KIN/nDJBQRcXw0MLVhZE9iQHmG68qAVIBg9CqmUYjmQIhgij9U5MFvrqkUL5FbtyyzZuOeOt0zdeRe4UY7ct+A==",
+      "license": "MIT",
+      "dependencies": {
+        "call-bind-apply-helpers": "^1.0.1",
+        "es-errors": "^1.3.0",
+        "gopd": "^1.2.0"
+      },
+      "engines": {
+        "node": ">= 0.4"
+      }
+    },
     "node_modules/ejs": {
       "version": "3.1.10",
       "resolved": "https://registry.npmjs.org/ejs/-/ejs-3.1.10.tgz",
@@ -2825,6 +2858,51 @@
         "is-arrayish": "^0.2.1"
       }
     },
+    "node_modules/es-define-property": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/es-define-property/-/es-define-property-1.0.1.tgz",
+      "integrity": "sha512-e3nRfgfUZ4rNGL232gUgX06QNyyez04KdjFrF+LTRoOXmrOgFKDg4BCdsjW8EnT69eqdYGmRpJwiPVYNrCaW3g==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 0.4"
+      }
+    },
+    "node_modules/es-errors": {
+      "version": "1.3.0",
+      "resolved": "https://registry.npmjs.org/es-errors/-/es-errors-1.3.0.tgz",
+      "integrity": "sha512-Zf5H2Kxt2xjTvbJvP2ZWLEICxA6j+hAmMzIlypy4xcBg1vKVnx89Wy0GbS+kf5cwCVFFzdCFh2XSCFNULS6csw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 0.4"
+      }
+    },
+    "node_modules/es-object-atoms": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/es-object-atoms/-/es-object-atoms-1.1.1.tgz",
+      "integrity": "sha512-FGgH2h8zKNim9ljj7dankFPcICIK9Cp5bm+c2gQSYePhpaG5+esrLODihIorn+Pe6FGJzWhXQotPv73jTaldXA==",
+      "license": "MIT",
+      "dependencies": {
+        "es-errors": "^1.3.0"
+      },
+      "engines": {
+        "node": ">= 0.4"
+      }
+    },
+    "node_modules/es-set-tostringtag": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/es-set-tostringtag/-/es-set-tostringtag-2.1.0.tgz",
+      "integrity": "sha512-j6vWzfrGVfyXxge+O0x5sh6cvxAog0a/4Rdd2K36zCMV5eJ+/+tOAngRO8cODMNWbVRdVlmGZQL2YS3yR8bIUA==",
+      "license": "MIT",
+      "dependencies": {
+        "es-errors": "^1.3.0",
+        "get-intrinsic": "^1.2.6",
+        "has-tostringtag": "^1.0.2",
+        "hasown": "^2.0.2"
+      },
+      "engines": {
+        "node": ">= 0.4"
+      }
+    },
     "node_modules/escalade": {
       "version": "3.1.1",
       "resolved": "https://registry.npmjs.org/escalade/-/escalade-3.1.1.tgz",
@@ -3353,13 +3431,17 @@
       "dev": true
     },
     "node_modules/form-data": {
-      "version": "2.5.1",
+      "version": "2.5.5",
-      "resolved": "https://registry.npmjs.org/form-data/-/form-data-2.5.1.tgz",
+      "resolved": "https://registry.npmjs.org/form-data/-/form-data-2.5.5.tgz",
-      "integrity": "sha512-m21N3WOmEEURgk6B9GLOE4RuWOFf28Lhh9qGYeNlGq4VDXUlJy2th2slBNU8Gp8EzloYZOibZJ7t5ecIrFSjVA==",
+      "integrity": "sha512-jqdObeR2rxZZbPSGL+3VckHMYtu+f9//KXBsVny6JSX/pa38Fy+bGjuG8eW/H6USNQWhLi8Num++cU2yOCNz4A==",
+      "license": "MIT",
       "dependencies": {
         "asynckit": "^0.4.0",
-        "combined-stream": "^1.0.6",
+        "combined-stream": "^1.0.8",
-        "mime-types": "^2.1.12"
+        "es-set-tostringtag": "^2.1.0",
+        "hasown": "^2.0.2",
+        "mime-types": "^2.1.35",
+        "safe-buffer": "^5.2.1"
       },
       "engines": {
         "node": ">= 0.12"
@@ -3389,7 +3471,6 @@
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/function-bind/-/function-bind-1.1.2.tgz",
       "integrity": "sha512-7XHNxH7qX9xG5mIwxkhumTox/MIRNcOgDrxWsMt2pAr23WHp6MrRlN7FBSFpCpr+oVO0F744iUgR82nJMfG2SA==",
-      "dev": true,
       "funding": {
         "url": "https://github.com/sponsors/ljharb"
       }
@@ -3431,15 +3512,24 @@
       }
     },
     "node_modules/get-intrinsic": {
-      "version": "1.2.2",
+      "version": "1.3.0",
-      "resolved": "https://registry.npmjs.org/get-intrinsic/-/get-intrinsic-1.2.2.tgz",
+      "resolved": "https://registry.npmjs.org/get-intrinsic/-/get-intrinsic-1.3.0.tgz",
-      "integrity": "sha512-0gSo4ml/0j98Y3lngkFEot/zhiCeWsbYIlZ+uZOVgzLyLaUw7wxUL+nCTP0XJvJg1AXulJRI3UJi8GsbDuxdGA==",
+      "integrity": "sha512-9fSjSaos/fRIVIp+xSJlE6lfwhES7LNtKaCBIamHsjr2na1BiABJPo0mOjjz8GJDURarmCPGqaiVg5mfjb98CQ==",
-      "dev": true,
+      "license": "MIT",
       "dependencies": {
+        "call-bind-apply-helpers": "^1.0.2",
+        "es-define-property": "^1.0.1",
+        "es-errors": "^1.3.0",
+        "es-object-atoms": "^1.1.1",
         "function-bind": "^1.1.2",
-        "has-proto": "^1.0.1",
+        "get-proto": "^1.0.1",
-        "has-symbols": "^1.0.3",
+        "gopd": "^1.2.0",
-        "hasown": "^2.0.0"
+        "has-symbols": "^1.1.0",
+        "hasown": "^2.0.2",
+        "math-intrinsics": "^1.1.0"
+      },
+      "engines": {
+        "node": ">= 0.4"
       },
       "funding": {
         "url": "https://github.com/sponsors/ljharb"
@@ -3454,6 +3544,19 @@
         "node": ">=8.0.0"
       }
     },
+    "node_modules/get-proto": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/get-proto/-/get-proto-1.0.1.tgz",
+      "integrity": "sha512-sTSfBjoXBp89JvIKIefqw7U2CCebsc74kiY6awiGogKtoSGbgjYE/G/+l9sF3MWFPNc9IcoOC4ODfKHfxFmp0g==",
+      "license": "MIT",
+      "dependencies": {
+        "dunder-proto": "^1.0.1",
+        "es-object-atoms": "^1.0.0"
+      },
+      "engines": {
+        "node": ">= 0.4"
+      }
+    },
     "node_modules/get-stream": {
       "version": "6.0.1",
       "resolved": "https://registry.npmjs.org/get-stream/-/get-stream-6.0.1.tgz",
@@ -3514,12 +3617,12 @@
       }
     },
     "node_modules/gopd": {
-      "version": "1.0.1",
+      "version": "1.2.0",
-      "resolved": "https://registry.npmjs.org/gopd/-/gopd-1.0.1.tgz",
+      "resolved": "https://registry.npmjs.org/gopd/-/gopd-1.2.0.tgz",
-      "integrity": "sha512-d65bNlIadxvpb/A2abVdlqKqV563juRnZ1Wtk6s1sIR8uNsXR70xqIzVqxVf1eTqDunwT2MkczEeaezCKTZhwA==",
+      "integrity": "sha512-ZUKRh6/kUFoAiTAtTYPZJ3hw9wNxx+BIBOijnlG9PnrJsCcSjs1wyyD6vJpaYtgnzDrKYRSqf3OO6Rfa93xsRg==",
-      "dev": true,
+      "license": "MIT",
-      "dependencies": {
+      "engines": {
-        "get-intrinsic": "^1.1.3"
+        "node": ">= 0.4"
       },
       "funding": {
         "url": "https://github.com/sponsors/ljharb"
@@ -3558,23 +3661,11 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
-    "node_modules/has-proto": {
-      "version": "1.0.1",
-      "resolved": "https://registry.npmjs.org/has-proto/-/has-proto-1.0.1.tgz",
-      "integrity": "sha512-7qE+iP+O+bgF9clE5+UoBFzE65mlBiVj3tKCrlNQ0Ogwm0BjpT/gK4SlLYDMybDh5I3TCTKnPPa0oMG7JDYrhg==",
-      "dev": true,
-      "engines": {
-        "node": ">= 0.4"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/ljharb"
-      }
-    },
     "node_modules/has-symbols": {
-      "version": "1.0.3",
+      "version": "1.1.0",
-      "resolved": "https://registry.npmjs.org/has-symbols/-/has-symbols-1.0.3.tgz",
+      "resolved": "https://registry.npmjs.org/has-symbols/-/has-symbols-1.1.0.tgz",
-      "integrity": "sha512-l3LCuF6MgDNwTDKkdYGEihYjt5pRPbEg46rtlmnSPlUbgmB8LOIrKJbYYFBSbnPaJexMKtiPO8hmeRjRz2Td+A==",
+      "integrity": "sha512-1cDNdwJ2Jaohmb3sg4OmKaMBwuC48sYni5HUw2DvsC8LjGTLK9h+eb1X6RyuOHe4hT0ULCW68iomhjUoKUqlPQ==",
-      "dev": true,
+      "license": "MIT",
       "engines": {
         "node": ">= 0.4"
       },
@@ -3583,12 +3674,12 @@
       }
     },
     "node_modules/has-tostringtag": {
-      "version": "1.0.0",
+      "version": "1.0.2",
-      "resolved": "https://registry.npmjs.org/has-tostringtag/-/has-tostringtag-1.0.0.tgz",
+      "resolved": "https://registry.npmjs.org/has-tostringtag/-/has-tostringtag-1.0.2.tgz",
-      "integrity": "sha512-kFjcSNhnlGV1kyoGk7OXKSawH5JOb/LzUc5w9B02hOTO0dfFRjbHQKvg1d6cf3HbeUmtU9VbbV3qzZ2Teh97WQ==",
+      "integrity": "sha512-NqADB8VjPFLM2V0VvHUewwwsw0ZWBaIdgo+ieHtK3hasLz4qeCRjYcqfB6AQrBggRKppKF8L52/VqdVsO47Dlw==",
-      "dev": true,
+      "license": "MIT",
       "dependencies": {
-        "has-symbols": "^1.0.2"
+        "has-symbols": "^1.0.3"
       },
       "engines": {
         "node": ">= 0.4"
@@ -3598,10 +3689,10 @@
       }
     },
     "node_modules/hasown": {
-      "version": "2.0.0",
+      "version": "2.0.2",
-      "resolved": "https://registry.npmjs.org/hasown/-/hasown-2.0.0.tgz",
+      "resolved": "https://registry.npmjs.org/hasown/-/hasown-2.0.2.tgz",
-      "integrity": "sha512-vUptKVTpIJhcczKBbgnS+RtcuYMB8+oNzPK2/Hp3hanz8JmpATdmmgLgSaadVREkDm+e2giHwY3ZRkyjSIDDFA==",
+      "integrity": "sha512-0hJU9SCPvmMzIBdZFqNPXWa6dqh7WdH0cII9y+CyS8rG3nL48Bclra9HmKhVVUHyPWNH5Y7xDwAB7bfgSjkUMQ==",
-      "dev": true,
+      "license": "MIT",
       "dependencies": {
         "function-bind": "^1.1.2"
       },
@@ -4674,6 +4765,15 @@
         "tmpl": "1.0.5"
       }
     },
+    "node_modules/math-intrinsics": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/math-intrinsics/-/math-intrinsics-1.1.0.tgz",
+      "integrity": "sha512-/IXtbwEk5HTPyEwyKX6hGkYXxM9nbj64B+ilVJnC/R6B0pH5G4V3b0pVbL7DBj4tkhBAppbQUlf6F6Xl9LHu1g==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 0.4"
+      }
+    },
     "node_modules/merge-stream": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/merge-stream/-/merge-stream-2.0.0.tgz",
@@ -5421,6 +5521,26 @@
         "queue-microtask": "^1.2.2"
       }
     },
+    "node_modules/safe-buffer": {
+      "version": "5.2.1",
+      "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.2.1.tgz",
+      "integrity": "sha512-rp3So07KcdmmKbGvgaNxQSJr7bGVSVk5S9Eq1F+ppbRo70+YeaDxkw5Dd8NPN+GD6bjnYm2VuPuCXmpuYvmCXQ==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/feross"
+        },
+        {
+          "type": "patreon",
+          "url": "https://www.patreon.com/feross"
+        },
+        {
+          "type": "consulting",
+          "url": "https://feross.org/support"
+        }
+      ],
+      "license": "MIT"
+    },
     "node_modules/sax": {
       "version": "1.3.0",
       "resolved": "https://registry.npmjs.org/sax/-/sax-1.3.0.tgz",

src/installer.ts

@@ -8,6 +8,8 @@ import fs from 'fs';
 import os from 'os';
 import {StableReleaseAlias, isSelfHosted} from './utils';
 
+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';
@@ -495,8 +497,21 @@ export function parseGoVersionFile(versionFilePath: string): string {
     path.basename(versionFilePath) === 'go.mod' ||
     path.basename(versionFilePath) === 'go.work'
   ) {
-    const match = contents.match(/^go (\d+(\.\d+)*)/m);
+    // for backwards compatibility: use version from go directive if
-    return match ? match[1] : '';
+    // '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();

src/main.ts

@@ -16,6 +16,7 @@ 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}`);
@@ -160,3 +161,20 @@ 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
+  );
+}