npm run build

dist/index.js

@@ -1432,7 +1432,13 @@ function run() {
             // versionSpec is optional.  If supplied, install / use from the tool cache
             // If not supplied then problem matchers will still be setup.  Useful for self-hosted.
             //
-            let versionSpec = core.getInput('go-version');
+            const versionFilePath = core.getInput('go-version-from-file');
+            const versionSpecFromFile = versionFilePath &&
+                fs_1.default
+                    .readFileSync(versionFilePath)
+                    .toString()
+                    .trim();
+            let versionSpec = core.getInput('go-version') || versionSpecFromFile;
             // stable will be true unless false is the exact input
             // since getting unstable versions should be explicit
             let stable = (core.getInput('stable') || 'true').toUpperCase() === 'TRUE';