chore(cloudfront): add validation for length of comment in cache poli…

…cy (aws#31251)

### Issue # (if applicable)

Closes aws#31248 .

### Reason for this change



CDK doesn't validate the comment's length in the cache policy now.

### Description of changes



Add validation for the length.

### Description of how you validated changes



unit tests.

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/aws-cdk-lib/aws-cloudfront/lib/cache-policy.ts

@@ -26,6 +26,9 @@ export interface CachePolicyProps {
 
   /**
    * A comment to describe the cache policy.
+   *
+   * The comment cannot be longer than 128 characters.
+   *
    * @default - no comment
    */
   readonly comment?: string;
@@ -149,6 +152,10 @@ export class CachePolicy extends Resource implements ICachePolicy {
       throw new Error(`'cachePolicyName' cannot be longer than 128 characters, got: '${cachePolicyName.length}'`);
     }
 
+    if (props.comment && !Token.isUnresolved(props.comment) && props.comment.length > 128) {
+      throw new Error(`'comment' cannot be longer than 128 characters, got: ${props.comment.length}`);
+    }
+
     const minTtl = (props.minTtl ?? Duration.seconds(0)).toSeconds();
     let defaultTtl = (props.defaultTtl ?? Duration.days(1)).toSeconds();
     let maxTtl = (props.maxTtl ?? Duration.days(365)).toSeconds();

packages/aws-cdk-lib/aws-cloudfront/test/cache-policy.test.ts

@@ -108,6 +108,11 @@ describe('CachePolicy', () => {
     })).not.toThrow();
   });
 
+  test('throws on long comment over 128 characters', () => {
+    const errorMessage = /'comment' cannot be longer than 128 characters, got: 129/;
+    expect(() => new CachePolicy(stack, 'CachePolicy1', { comment: 'a'.repeat(129) })).toThrow(errorMessage);
+  });
+
   describe('TTLs', () => {
     test('default TTLs', () => {
       new CachePolicy(stack, 'CachePolicy', { cachePolicyName: 'MyPolicy' });