feat(aws-lambda): support dead letter queues (#663)

Adds support for DLQ configuration in Lambda

CHANGELOG.md

@@ -49,6 +49,7 @@
     - AWS::Glue::Classifier JsonClassifier (__added__)
     - AWS::Glue::Classifier XMLClassifier (__added__)
     - AWS::Glue::Crawler Configuration (__added__)
+    - AWS::Lambda::Lambda DLQConfigurationSupport (__added__)
     - AWS::Neptune::DBInstance DBSubnetGroupName.UpdateType (__changed__)
       - Old: Mutable
       - New: Immutable

packages/@aws-cdk/aws-lambda/README.md

@@ -60,3 +60,18 @@ new lambda.PipelineInvokeAction(this, 'Lambda', {
 
 See [the AWS documentation](https://docs.aws.amazon.com/codepipeline/latest/userguide/actions-invoke-lambda-function.html)
 on how to write a Lambda function invoked from CodePipeline.
+
+### Lambda with DLQ 
+
+```ts
+import lambda = require('@aws-cdk/aws-lambda');
+
+const fn = new lambda.Function(this, 'MyFunction', {
+    runtime: lambda.Runtime.NodeJS810,
+    handler: 'index.handler'
+    code: lambda.Code.inline('exports.handler = function(event, ctx, cb) { return cb(null, "hi"); }'),
+    deadLetterQueueEnabled: true
+});
+```
+See [the AWS documentation](https://docs.aws.amazon.com/lambda/latest/dg/dlq.html)
+to learn more about AWS Lambdas and DLQs.

packages/@aws-cdk/aws-lambda/lib/lambda.ts

@@ -1,4 +1,5 @@
 import iam = require('@aws-cdk/aws-iam');
+import sqs = require('@aws-cdk/aws-sqs');
 import cdk = require('@aws-cdk/cdk');
 import { Code } from './code';
 import { FunctionRef } from './lambda-ref';
@@ -89,6 +90,22 @@ export interface FunctionProps {
      * Both supplied and generated roles can always be changed by calling `addToRolePolicy`.
      */
     role?: iam.Role;
+
+    /**
+     * Enabled DLQ. If `deadLetterQueue` is undefined,
+     * an SQS queue with default options will be defined for your Function.
+     *
+     * @default false unless `deadLetterQueue` is set, which implies DLQ is enabled
+     */
+    deadLetterQueueEnabled?: boolean;
+
+    /**
+     * The SQS queue to use if DLQ is enabled.
+     *
+     * @default SQS queue with 14 day retention period if `deadLetterQueueEnabled` is `true`
+     */
+    deadLetterQueue?: sqs.QueueRef;
+
 }
 
 /**
@@ -166,6 +183,7 @@ export class Function extends FunctionRef {
             role: this.role.roleArn,
             environment: new cdk.Token(() => this.renderEnvironment()),
             memorySize: props.memorySize,
+            deadLetterConfig: this.buildDeadLetterConfig(props),
         });
 
         resource.addDependency(this.role);
@@ -226,4 +244,27 @@ export class Function extends FunctionRef {
             variables: this.environment
         };
     }
+
+    private buildDeadLetterConfig(props: FunctionProps) {
+        if (props.deadLetterQueue && props.deadLetterQueueEnabled === false) {
+            throw Error('deadLetterQueue defined but deadLetterQueueEnabled explicitly set to false');
+        }
+
+        if (!props.deadLetterQueue && !props.deadLetterQueueEnabled) {
+            return undefined;
+        }
+
+        const deadLetterQueue = props.deadLetterQueue || new sqs.Queue(this, 'DeadLetterQueue', {
+            retentionPeriodSec: 1209600
+        });
+
+        this.addToRolePolicy(new cdk.PolicyStatement()
+            .addAction('sqs:SendMessage')
+            .addResource(deadLetterQueue.queueArn));
+
+        return {
+            targetArn: deadLetterQueue.queueArn
+        };
+    }
+
 }

packages/@aws-cdk/aws-lambda/package.json

@@ -64,6 +64,7 @@
     "@aws-cdk/aws-logs": "^0.8.2",
     "@aws-cdk/aws-s3": "^0.8.2",
     "@aws-cdk/aws-s3-notifications": "^0.8.2",
+    "@aws-cdk/aws-sqs": "^0.8.2",
     "@aws-cdk/cdk": "^0.8.2",
     "@aws-cdk/cx-api": "^0.8.2"
   },