Dead letter queues (DLQ) is a defined mechanism by Amazon to trace the failure of AWS Lambda functions executing asynchronously. AWS Lambda invokes asynchronous mode and retires it twice in case of failure before the event is discarded. DLQ is used to proceed this failure event to an Amazon SQS queue or Amazon SNS topic.
DLQ can be configured by setting TargetArn (that is, the SQS queue ARN or SNS topic ARN) on the Lambda function's DeadLetterConfig parameter, as mentioned here:
{
"Code": {
"ZipFile": blob,
"S3Bucket": “string”,
"S3Key": “string”,
"S3ObjectVersion": “string”
},
"Description": "string",
"FunctionName": "string",
"Handler": "string",
"MemorySize": number,
"Role": "string",
"Runtime": "string",
"Timeout": number
"Publish": bool,
"DeadLetterConfig": {
"TargetArn": "string"
}
}