Lambda Dead Letter Queue Missing

What this rule checks

Detects Lambda functions without dead letter queue configuration.

How to fix it

1. 1Configure a dead letter queue (SQS or SNS)
2. 2Set up monitoring for DLQ messages
3. 3Implement retry logic for failed invocations

import * as lambda from 'aws-cdk-lib/aws-lambda';

// Async-invoked (EventBridge) with no DLQ: after retries are exhausted,
// failed events are dropped.
const fn = new lambda.Function(this, 'Fn', {
  runtime: lambda.Runtime.NODEJS_20_X,
  handler: 'index.handler',
  code: lambda.Code.fromInline('exports.handler = async () => {};'),
});
new lambda.CfnPermission(this, 'EventsPermission', {
  action: 'lambda:InvokeFunction',
  functionName: fn.functionName,
  principal: 'events.amazonaws.com',
  sourceArn: 'arn:aws:events:eu-west-2:111122223333:rule/tick',
});

import * as lambda from 'aws-cdk-lib/aws-lambda';
import * as sqs from 'aws-cdk-lib/aws-sqs';

const dlq = new sqs.Queue(this, 'Dlq', { enforceSSL: true });
const fn = new lambda.Function(this, 'Fn', {
  runtime: lambda.Runtime.NODEJS_20_X,
  handler: 'index.handler',
  code: lambda.Code.fromInline('exports.handler = async () => {};'),
  deadLetterQueue: dlq,
});
new lambda.CfnPermission(this, 'EventsPermission', {
  action: 'lambda:InvokeFunction',
  functionName: fn.functionName,
  principal: 'events.amazonaws.com',
  sourceArn: 'arn:aws:events:eu-west-2:111122223333:rule/tick',
});

CDK Insights pinpoints the exact file and line in your CDK source for every finding, so you can jump straight to the fix.

Affected resource types

Intentional? Suppress this finding

Sometimes a flag is deliberate — a genuinely public endpoint, say. You can dismiss lambda-dlq-missing and the reason is kept in the report, not silently hidden.

In .cdk-insights.json:

{
  "ignoreRules": [
    { "id": "lambda-dlq-missing", "reason": "Why this is intentional" }
  ]
}

Or inline in your CDK code:

Validations.of(scope).acknowledge({
  id: 'cdk-insights::lambda-dlq-missing',
  reason: 'Why this is intentional',
});

Use the rule ID lambda-dlq-missing shown above — not the CDK-* ID from SARIF / GitHub code scanning. To dismiss every finding on one construct instead, use ignorePaths. Suppression docs →

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