feat(events): dead letter queue for an Event Bus (aws#30628)

### Issue # (if applicable)

Closes aws#30531.

### Reason for this change

EventBus L2 construct doesn't support for configuring dead letter queue.

### Description of changes

Add `deadLetterQueue` prop to `EventBusProps`

### Description of how you validated changes

Add both unit and integ test

### 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-testing/framework-integ/test/aws-events/test/integ.eventbus.js.snapshot/Stack.template.json

@@ -1,8 +1,21 @@
 {
  "Resources": {
+  "DLQ581697C4": {
+   "Type": "AWS::SQS::Queue",
+   "UpdateReplacePolicy": "Delete",
+   "DeletionPolicy": "Delete"
+  },
   "BusEA82B648": {
    "Type": "AWS::Events::EventBus",
    "Properties": {
+    "DeadLetterConfig": {
+     "Arn": {
+      "Fn::GetAtt": [
+       "DLQ581697C4",
+       "Arn"
+      ]
+     }
+    },
     "Description": "myEventBus",
     "Name": "StackBusAA0A1E4B"
    }

packages/@aws-cdk-testing/framework-integ/test/aws-events/test/integ.eventbus.ts

@@ -1,11 +1,16 @@
 import * as iam from 'aws-cdk-lib/aws-iam';
+import * as sqs from 'aws-cdk-lib/aws-sqs';
 import { App, Stack } from 'aws-cdk-lib';
 import { IntegTest } from '@aws-cdk/integ-tests-alpha';
 import { EventBus } from 'aws-cdk-lib/aws-events';
 
 const app = new App();
 const stack = new Stack(app, 'Stack');
+
+const dlq = new sqs.Queue(stack, 'DLQ');
+
 const bus = new EventBus(stack, 'Bus', {
+  deadLetterQueue: dlq,
   description: 'myEventBus',
 });
 

packages/aws-cdk-lib/aws-events/README.md

@@ -222,6 +222,22 @@ bus.archive('MyArchive', {
 });
 ```
 
+## Dead-Letter Queue for EventBus
+
+It is possible to configure a [Dead Letter Queue for an EventBus](https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-rule-event-delivery.html#eb-rule-dlq). This is useful when you want to capture events that could not be delivered to any of the targets.
+
+To configure a Dead Letter Queue for an EventBus, you can use the `deadLetterQueue` property of the `EventBus` construct.
+
+```ts
+import * as sqs from 'aws-cdk-lib/aws-sqs';
+
+const dlq = new sqs.Queue(this, 'DLQ');
+
+const bus = new events.EventBus(this, 'Bus', {
+  deadLetterQueue: dlq,
+});
+```
+
 ## Granting PutEvents to an existing EventBus
 
 To import an existing EventBus into your CDK application, use `EventBus.fromEventBusArn`, `EventBus.fromEventBusAttributes`

packages/aws-cdk-lib/aws-events/lib/event-bus.ts

@@ -3,6 +3,7 @@ import { Archive, BaseArchiveProps } from './archive';
 import { CfnEventBus, CfnEventBusPolicy } from './events.generated';
 import * as iam from '../../aws-iam';
 import * as kms from '../../aws-kms';
+import * as sqs from '../../aws-sqs';
 import { ArnFormat, IResource, Lazy, Names, Resource, Stack, Token } from '../../core';
 
 /**
@@ -80,6 +81,15 @@ export interface EventBusProps {
    */
   readonly eventSourceName?: string;
 
+  /**
+   * Dead-letter queue for the event bus
+   *
+   * @see https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-rule-event-delivery.html#eb-rule-dlq
+   *
+   * @default - no dead-letter queue
+   */
+  readonly deadLetterQueue?: sqs.IQueue;
+
   /**
    * The event bus description.
    *
@@ -343,6 +353,9 @@ export class EventBus extends EventBusBase {
     const eventBus = new CfnEventBus(this, 'Resource', {
       name: this.physicalName,
       eventSourceName,
+      deadLetterConfig: props?.deadLetterQueue ? {
+        arn: props.deadLetterQueue.queueArn,
+      } : undefined,
       description: props?.description,
       kmsKeyIdentifier: props?.kmsKey?.keyArn,
     });

packages/aws-cdk-lib/aws-events/test/event-bus.test.ts

@@ -1,8 +1,8 @@
 import { testDeprecated } from '@aws-cdk/cdk-build-tools';
 import { Template } from '../../assertions';
 import * as iam from '../../aws-iam';
-import { Effect } from '../../aws-iam';
 import * as kms from '../../aws-kms';
+import * as sqs from '../../aws-sqs';
 import { Aws, CfnResource, Stack, Arn, App, PhysicalName, CfnOutput } from '../../core';
 import { EventBus } from '../lib';
 
@@ -568,7 +568,7 @@ describe('event bus', () => {
 
     // WHEN
     bus.addToResourcePolicy(new iam.PolicyStatement({
-      effect: Effect.ALLOW,
+      effect: iam.Effect.ALLOW,
       principals: [new iam.AccountPrincipal('111111111111111')],
       actions: ['events:PutEvents'],
       sid: '123',
@@ -616,15 +616,15 @@ describe('event bus', () => {
     const bus = new EventBus(stack, 'Bus');
 
     const statement1 = new iam.PolicyStatement({
-      effect: Effect.ALLOW,
+      effect: iam.Effect.ALLOW,
       principals: [new iam.ArnPrincipal('arn')],
       actions: ['events:PutEvents'],
       sid: 'statement1',
       resources: [bus.eventBusArn],
     });
 
     const statement2 = new iam.PolicyStatement({
-      effect: Effect.ALLOW,
+      effect: iam.Effect.ALLOW,
       principals: [new iam.ArnPrincipal('arn')],
       actions: ['events:DeleteRule'],
       sid: 'statement2',
@@ -649,12 +649,28 @@ describe('event bus', () => {
 
     // THEN
     expect(() => bus.addToResourcePolicy(new iam.PolicyStatement({
-      effect: Effect.ALLOW,
+      effect: iam.Effect.ALLOW,
       principals: [new iam.ArnPrincipal('arn')],
       actions: ['events:PutEvents'],
     }))).toThrow('Event Bus policy statements must have a sid');
   });
 
+  test('set dead letter queue', () => {
+    const app = new App();
+    const stack = new Stack(app, 'Stack');
+    const dlq = new sqs.Queue(stack, 'DLQ');
+    new EventBus(stack, 'Bus', {
+      deadLetterQueue: dlq,
+    });
+
+    Template.fromStack(stack).hasResourceProperties('AWS::Events::EventBus', {
+      DeadLetterConfig: {
+        Arn: {
+          'Fn::GetAtt': ['DLQ581697C4', 'Arn'],
+        },
+      },
+    });
+  });
   test('Event Bus with a customer managed key', () => {
     // GIVEN
     const app = new App();