feat: add option pulumi-version-file

action.yml

@@ -15,6 +15,9 @@ inputs:
     description: 'Install a specific version of the Pulumi CLI'
     required: false
     default: '^3'
+  pulumi-version-file:
+    description: 'File containing the version of the Pulumi CLI to install. Example: .pulumi.version'
+    required: false
   work-dir:
     description: 'Location of your Pulumi files. Defaults to ./'
     required: false

src/__tests__/run.test.ts

@@ -47,6 +47,61 @@ describe('Config without a provided command', () => {
       pulumiVersion: '^2',
     });
   });
+
+  it('should read version from pulumi-version-file', async () => {
+    jest.mock('fs', () => ({
+      ...jest.requireActual('fs'),
+      readFileSync: jest.fn((path: string) => {
+        expect(path).toEqual('.pulumi.version');
+        return '3.121.0';
+      }),
+      existsSync: jest.fn(() => {
+        return true;
+      }),
+    }));
+    jest.mock('@actions/core', () => ({
+      getInput: jest.fn((name: string) => {
+        if (name === 'pulumi-version-file') {
+          return '.pulumi.version';
+        }
+        return installConfig[name];
+      }),
+    }));
+
+    const { makeInstallationConfig } = require('../config');
+    const conf = makeInstallationConfig();
+    expect(conf.success).toBeTruthy();
+    expect(conf.value).toEqual({
+      command: undefined,
+      pulumiVersion: '3.121.0',
+    });
+  });
+
+  it('should fail if pulumi-version-file does not exist', async () => {
+    jest.mock('fs', () => ({
+      ...jest.requireActual('fs'),
+      readFileSync: jest.fn((path: string) => {
+        expect(path).toEqual('.pulumi.version');
+        return '3.121.0';
+      }),
+      existsSync: jest.fn(() => {
+        return false;
+      }),
+    }));
+    jest.mock('@actions/core', () => ({
+      getInput: jest.fn((name: string) => {
+        if (name === 'pulumi-version-file') {
+          return '.pulumi.version';
+        }
+        return installConfig[name];
+      }),
+    }));
+
+    const { makeInstallationConfig } = require('../config');
+    expect(() => {
+      makeInstallationConfig();
+    }).toThrow(/pulumi-version-file '\.pulumi\.version' does not exist/);
+  });
 });
 
 describe('main.login', () => {

src/config.ts

@@ -1,3 +1,4 @@
+import * as fs from 'fs';
 import { ConfigMap } from '@pulumi/pulumi/automation';
 import {
   getBooleanInput,
@@ -22,9 +23,20 @@ export const installationConfig = rt.Record({
 export type InstallationConfig = rt.Static<typeof installationConfig>;
 
 export function makeInstallationConfig(): rt.Result<InstallationConfig> {
+  let pulumiVersion = getInput('pulumi-version') || '^3';
+  const versionFile = getInput('pulumi-version-file');
+  if (versionFile) {
+    if (fs.existsSync(versionFile)) {
+      pulumiVersion = fs
+        .readFileSync(versionFile, { encoding: 'utf-8' })
+        .trim();
+    } else {
+      throw new Error(`pulumi-version-file '${versionFile}' does not exist`);
+    }
+  }
   return installationConfig.validate({
     command: getInput('command') || undefined,
-    pulumiVersion: getInput('pulumi-version') || '^3',
+    pulumiVersion,
   });
 }
 
@@ -33,7 +45,14 @@ export function makeConfig() {
   return {
     command: getUnionInput('command', {
       required: true,
-      alternatives: ['up', 'update', 'refresh', 'destroy', 'preview', 'output'] as const,
+      alternatives: [
+        'up',
+        'update',
+        'refresh',
+        'destroy',
+        'preview',
+        'output',
+      ] as const,
     }),
     stackName: getInput('stack-name', { required: true }),
     pulumiVersion: getInput('pulumi-version', { required: true }),