feat: add version_file input to read the gcloud version from a file

README.md

@@ -82,6 +82,18 @@ jobs:
     You are responsible for ensuring the `gcloud` version matches the features
     and components required.
 
+-   <a name="__input_version_file"></a><a href="#user-content-__input_version_file"><code>version_file</code></a>: _(Optional)_ Path to a file containing the version or version constraint of the Cloud
+    SDK (`gcloud`) to install. Both a plain version file (containing only a
+    version string) and an asdf/mise-style `.tool-versions` file (containing a
+    `gcloud <version>` line) are supported:
+
+        - uses: 'google-github-actions/setup-gcloud@v3'
+          with:
+            version_file: '.tool-versions'
+
+    The `version` input takes precedence: if `version` is set to anything other
+    than the default `"latest"`, `version_file` is ignored.
+
 -   <a name="__input_project_id"></a><a href="#user-content-__input_project_id"><code>project_id</code></a>: _(Optional)_ ID of the Google Cloud project. If provided, this will configure gcloud to
     use this project ID by default for commands. Individual commands can still
     override the project using the `--project` flag which takes precedence. If

action.yml

@@ -48,6 +48,21 @@ inputs:
     default: 'latest'
     required: false
 
+  version_file:
+    description: |-
+      Path to a file containing the version or version constraint of the Cloud
+      SDK (`gcloud`) to install. Both a plain version file (containing only a
+      version string) and an asdf/mise-style `.tool-versions` file (containing a
+      `gcloud <version>` line) are supported:
+
+          - uses: 'google-github-actions/setup-gcloud@v3'
+            with:
+              version_file: '.tool-versions'
+
+      The `version` input takes precedence: if `version` is set to anything other
+      than the default `"latest"`, `version_file` is ignored.
+    required: false
+
   project_id:
     description: |-
       ID of the Google Cloud project. If provided, this will configure gcloud to

src/main.ts

@@ -31,12 +31,47 @@ import {
   parseBoolean,
   presence,
 } from '@google-github-actions/actions-utils';
+import { promises as fs } from 'fs';
 import path from 'path';
 
 // Do not listen to the linter - this can NOT be rewritten as an ES6 import
 // statement.
 const { version: appVersion } = require('../package.json');
 
+/**
+ * parseVersionFile extracts a gcloud version or version constraint from the
+ * contents of a version file. It supports asdf/mise-style ".tool-versions"
+ * files (a "gcloud <version>" line) as well as plain version files containing
+ * just a version string. Blank lines and "#" comments are ignored.
+ *
+ * @param contents The raw contents of the version file.
+ * @returns The resolved version string, or an empty string if none was found.
+ */
+export function parseVersionFile(contents: string): string {
+  const lines = contents.split(/\r?\n/);
+
+  // First, look for an asdf/mise ".tool-versions" entry ("gcloud <version>"),
+  // which may appear on any line. asdf uses the first token as the version.
+  for (const line of lines) {
+    const toolVersionsMatch = line.trim().match(/^gcloud\s+(\S+)/i);
+    if (toolVersionsMatch) {
+      return toolVersionsMatch[1];
+    }
+  }
+
+  // Otherwise treat the file as a plain version file and return the first
+  // non-comment, non-blank line, so that a version constraint such as
+  // ">= 416.0.0" is preserved.
+  for (const line of lines) {
+    const trimmed = line.trim();
+    if (trimmed && !trimmed.startsWith('#')) {
+      return trimmed;
+    }
+  }
+
+  return '';
+}
+
 export async function run(): Promise<void> {
   // Note: unlike the other actions, we actually want to export this as a
   // persistent variable for future steps. Other actions should set process.env
@@ -71,6 +106,28 @@ export async function run(): Promise<void> {
         );
       }
     } else {
+      // If a version file was provided, resolve the version from it. An
+      // explicitly-provided "version" (anything other than the default
+      // "latest") takes precedence over the file.
+      const versionFile = presence(core.getInput('version_file'));
+      if (versionFile) {
+        if (version && version !== 'latest') {
+          core.warning(
+            `Both "version" ("${version}") and "version_file" were specified; ` +
+              `using "version" and ignoring "version_file".`,
+          );
+        } else {
+          const contents = await fs.readFile(versionFile, 'utf8');
+          version = presence(parseVersionFile(contents));
+          if (!version) {
+            throw new Error(
+              `Failed to resolve a gcloud version from version_file "${versionFile}"`,
+            );
+          }
+          core.debug(`resolved version "${version}" from version_file "${versionFile}"`);
+        }
+      }
+
       // Compute the version information. If the version was not specified,
       // accept any installed version. If the version was specified as "latest",
       // compute the latest version. Otherwise, accept the version/version

tests/setup-gcloud.test.ts

@@ -17,13 +17,26 @@
 import { mock, test } from 'node:test';
 import assert from 'node:assert';
 
-import { promises as fs } from 'fs';
+import { promises as fs, writeFileSync } from 'fs';
+import * as os from 'os';
+import * as path from 'path';
 import * as setupGcloud from '@google-github-actions/setup-cloud-sdk';
 import { TestToolCache } from '@google-github-actions/setup-cloud-sdk';
 import * as core from '@actions/core';
 import * as toolCache from '@actions/tool-cache';
 
-import { run } from '../src/main';
+import { parseVersionFile, run } from '../src/main';
+
+/**
+ * writeTempVersionFile writes contents to a uniquely-named file in the OS temp
+ * directory and returns its path. It uses the synchronous fs API so it is
+ * unaffected by the mocked promise-based fs.writeFile in the test suite.
+ */
+const writeTempVersionFile = (name: string, contents: string): string => {
+  const tmp = path.join(os.tmpdir(), `setup-gcloud-${process.hrtime.bigint()}-${name}`);
+  writeFileSync(tmp, contents);
+  return tmp;
+};
 
 // These are mock data for github actions inputs, where camel case is expected.
 const fakeInputs: { [key: string]: string } = {
@@ -214,6 +227,61 @@ test('#run', { concurrency: true }, async (suite) => {
 
     assert.deepStrictEqual(mocks.setProject.mock.callCount(), 0);
   });
+
+  await suite.test('resolves the version from a .tool-versions version_file', async (t) => {
+    const versionFile = writeTempVersionFile('.tool-versions', 'nodejs 20.0.0\ngcloud 5.6.7\n');
+    const mocks = defaultMocks(t.mock, {
+      version: '',
+      version_file: versionFile,
+    });
+    await run();
+
+    assert.deepStrictEqual(mocks.installGcloudSDK.mock.calls?.at(0)?.arguments?.at(0), '5.6.7');
+  });
+
+  await suite.test('resolves the version from a plain version_file', async (t) => {
+    const versionFile = writeTempVersionFile('version', '5.6.7\n');
+    const mocks = defaultMocks(t.mock, {
+      version: '',
+      version_file: versionFile,
+    });
+    await run();
+
+    assert.deepStrictEqual(mocks.installGcloudSDK.mock.calls?.at(0)?.arguments?.at(0), '5.6.7');
+  });
+
+  await suite.test('prefers an explicit version over version_file', async (t) => {
+    const versionFile = writeTempVersionFile('version', '5.6.7\n');
+    const mocks = defaultMocks(t.mock, {
+      version: '9.9.9',
+      version_file: versionFile,
+    });
+    await run();
+
+    assert.deepStrictEqual(mocks.installGcloudSDK.mock.calls?.at(0)?.arguments?.at(0), '9.9.9');
+  });
+});
+
+test('#parseVersionFile', { concurrency: true }, async (suite) => {
+  await suite.test('extracts the gcloud entry from a .tool-versions file', async () => {
+    assert.deepStrictEqual(parseVersionFile('nodejs 20.0.0\ngcloud 416.0.0\n'), '416.0.0');
+  });
+
+  await suite.test('reads a plain version file', async () => {
+    assert.deepStrictEqual(parseVersionFile('416.0.0\n'), '416.0.0');
+  });
+
+  await suite.test('ignores comments and blank lines', async () => {
+    assert.deepStrictEqual(parseVersionFile('# comment\n\ngcloud 416.0.0\n'), '416.0.0');
+  });
+
+  await suite.test('preserves a version constraint', async () => {
+    assert.deepStrictEqual(parseVersionFile('>= 416.0.0\n'), '>= 416.0.0');
+  });
+
+  await suite.test('returns an empty string for an empty file', async () => {
+    assert.deepStrictEqual(parseVersionFile('\n# only a comment\n'), '');
+  });
 });
 
 /**