add go_version_file input

README.md

@@ -101,6 +101,11 @@ Optional. Additional reviewdog flags
 Optional. Install a specific version of Go.
 By default, the latest version of Go 1.x is installed.
 
+### `go_version_file`
+
+Optional. Install a specific version of Go from a file. It accepts a path to a `go.mod` file or a file containing only Go version.
+If both the `go_version` and the `go_version_file` inputs are provided then the `go_version` input is used.
+
 ### `cache`
 
 Optional. [`true`, `false`]

src/main.ts

@@ -19,6 +19,7 @@ async function run() {
     const reviewdogVersion = core.getInput("reviewdog_version") || "latest";
     const golangciLintVersion = core.getInput("golangci_lint_version") || "latest";
     const goVersion = core.getInput("go_version");
+    const goVersionFile = core.getInput("go_version_file");
     const golangciLintFlags = core.getInput("golangci_lint_flags");
     const toolName = core.getInput("tool_name") || "golangci";
     const level = core.getInput("level") || "error";
@@ -30,9 +31,9 @@ async function run() {
     const cwd = path.relative(process.env["GITHUB_WORKSPACE"] || process.cwd(), workdir);
     const enableCache = core.getBooleanInput("cache");
 
-    if (goVersion !== "") {
+    if (goVersion !== "" || goVersionFile !== "") {
       await core.group("Installing Go ...", async () => {
-        await setupGo.run(goVersion);
+        await setupGo.run(goVersion, goVersionFile);
       });
     }
 

src/setup-go/installer.ts

@@ -1,4 +1,4 @@
-// this file comes from https://github.com/actions/setup-go/blob/3b4dc6cbed1779f759b9c638cb83696acea809d1/src/installer.ts
+// this file comes from https://github.com/actions/setup-go/blob/b22fbbc2921299758641fab08929b4ac52b32923/src/installer.ts
 // see LICENSE for its license
 
 import * as core from "@actions/core";
@@ -8,6 +8,7 @@ import * as semver from "semver";
 import * as sys from "./system";
 import * as tc from "@actions/tool-cache";
 import os from "os";
+import fs from "fs";
 
 type InstallationType = "dist" | "manifest";
 
@@ -261,3 +262,14 @@ export function makeSemver(version: string): string {
   }
   return fullVersion;
 }
+
+export function parseGoVersionFile(versionFilePath: string): string {
+  const contents = fs.readFileSync(versionFilePath).toString();
+
+  if (path.basename(versionFilePath) === "go.mod") {
+    const match = contents.match(/^go (\d+(\.\d+)*)/m);
+    return match ? match[1] : "";
+  }
+
+  return contents.trim();
+}

src/setup-go/main.ts

@@ -1,4 +1,4 @@
-// this file comes from https://github.com/actions/setup-go/blob/3b4dc6cbed1779f759b9c638cb83696acea809d1/src/main.ts
+// this file comes from https://github.com/actions/setup-go/blob/b22fbbc2921299758641fab08929b4ac52b32923/src/main.ts
 // see LICENSE for its license
 
 import * as core from "@actions/core";
@@ -9,8 +9,13 @@ import cp from "child_process";
 import fs from "fs";
 import path from "path";
 
-export async function run(versionSpec: string): Promise<void> {
+export async function run(version: string, versionFilePath: string): Promise<void> {
   try {
+    const versionSpec = resolveVersionInput(version, versionFilePath);
+    if (versionSpec === "") {
+      return;
+    }
+
     core.info(`Setup go version spec ${versionSpec}`);
 
     if (versionSpec) {
@@ -78,3 +83,22 @@ function isGhes(): boolean {
   const ghUrl = new URL(process.env["GITHUB_SERVER_URL"] || "https://github.com");
   return ghUrl.hostname.toUpperCase() !== "GITHUB.COM";
 }
+
+function resolveVersionInput(version: string, versionFilePath: string): string {
+  if (version && versionFilePath) {
+    core.warning("Both go_version and go_version_file inputs are specified, only go_version will be used");
+  }
+
+  if (version) {
+    return version;
+  }
+
+  if (versionFilePath) {
+    if (!fs.existsSync(versionFilePath)) {
+      throw new Error(`The specified go version file at: ${versionFilePath} does not exist`);
+    }
+    version = installer.parseGoVersionFile(versionFilePath);
+  }
+
+  return version;
+}