Putting back messages on AWS SQS, for messages processed by Lambda but failed internally

Question

I am fairly new to the SQS Lambda integration and trying to understand the best approach for my use-case.

I have an SQS Lambda integration. My Lambda function is receiving messages from SQS and calls an external API to process the messages. The messages will be received one at a time by Lambda function, with batch size set to 1.

    @Override
    public Void handleRequest(SQSEvent event, Context context) {
        Response response = null;
        if (event != null) {
            for (SQSMessage msg : event.getRecords()) {
                response = callXXXAPI(msg.getBody(), reqId, logger);
            }
        }
            return null;
    }

I'm looking for a way to capture any error responses from the external API call and put back the messages which had failed response (non-200 status) on to the queue. These API-failed messages are not currently going back to the queue as they are considered "PROCESSED". Is there a way to do it with my current setup? Is it recommended?

The SQS also has a Dead Letter Queue.

Answer 1

If you modify your function code to throw an Exception when the API call fails, the Lambda/SQS integration will treat that as a failure and place the message back in the queue.

You will also need to configure Maximum receives to some number greater than 1 if you want the messages to be retried multiple times before being sent to the DLQ.