feat(cli): Support disabling version check

If AWS_CDK_DISABLE_VERSION_CHECK is defined, skip checking for newer
versions.

fixes aws#10974

packages/aws-cdk/README.md

@@ -345,3 +345,9 @@ Some of the interesting keys that can be used in the JSON configuration files:
     "versionReporting": false,         // Opt-out of version reporting      (--no-version-reporting)
 }
 ```
+
+#### Environment
+
+The following environment variables affect aws-cdk:
+
+- `AWS_CDK_DISABLE_VERSION_CHECK`: If set, disable automatic check for newer versions.

packages/aws-cdk/lib/version.ts

@@ -98,7 +98,7 @@ export async function latestVersionIfHigher(currentVersion: string, cacheFile: V
 }
 
 export async function displayVersionMessage(): Promise<void> {
-  if (!process.stdout.isTTY) {
+  if (!process.stdout.isTTY || process.env.AWS_CDK_DISABLE_VERSION_CHECK) {
     return;
   }
 

packages/aws-cdk/test/version.test.ts

@@ -3,7 +3,8 @@ import { setTimeout as _setTimeout } from 'timers';
 import { promisify } from 'util';
 import * as fs from 'fs-extra';
 import * as sinon from 'sinon';
-import { latestVersionIfHigher, VersionCheckTTL } from '../lib/version';
+import * as logging from '../lib/logging';
+import { latestVersionIfHigher, VersionCheckTTL, displayVersionMessage } from '../lib/version';
 
 const setTimeout = promisify(_setTimeout);
 
@@ -72,3 +73,11 @@ test('No Version specified for storage in the TTL file', async () => {
   const storedVersion = fs.readFileSync(cacheFile, 'utf8');
   expect(storedVersion).toBe('');
 });
+
+test('Skip version check if environment variable is set', async () => {
+  process.stdout.isTTY = true;
+  process.env.AWS_CDK_DISABLE_VERSION_CHECK = '1';
+  const printStub = sinon.stub(logging, 'print');
+  await displayVersionMessage();
+  expect(printStub.called).toEqual(false);
+});