Last week I merged Quarkus Live Coding and Continuous Testing support for Lambda and it will be available in Quarkus 2.3. I’m excited to see how its received by the Quarkus community. The PR allows you to run in Quarkus Dev or Test mode all locally within a mock Lambda environment automatically set up by the Quarkus build and runtime. This works when writing raw lambdas, with Quarkus’s Lambda + HTTP support, as well as with Funqy and Lambda. For all these integration points with Lambda, Quarkus provides an HTTP server that you can invoke on with Curl manually, or via Rest Assured or another HTTP client if you’re writing tests.

To completely understand what is going on here and how it works, I need to explain a little bit how Lambda’s work in general. Lambda’s (at least Java Lambdas) do not receive or process requests directly. Instead, an AWS Lambda event server is polled by your Lambda deployment for new requests that need to be processed. The AWS Lambda Java runtime has this poll loop built in. For native binary deployments with Graal VM, Quarkus re-implemented this poll loop itself.

The new Quarkus Live Coding and Continuous Testing support I merged has a new Mock Event Server that simulates the AWS Lambda event server. When running in Dev or Test mode, Quarkus boots up this Mock Event Server and runs your Lambda’s within the Quarkus poll loop. The Mock Event Server starts an HTTP server under port 8080 in Dev mode and port 8081 in Test mode. You can send requests to the event server with any HTTP client at http://localhost:8080 and http://localhost:8081 respectively. The payload of the request is sent as a Lambda event and is picked up by the poll loop and sent to your lambda code.

For Quarkus’s Lambda + HTTP support, the same Mock Event Server is started as well. In this case the Mock Event Server looks like a normal HTTP server to the client, but under the covers it automatically converts HTTP requests to the JSON HTTP event payload that the AWS API Gateway uses. If you want to send raw API Gateway HTTP events, you can by posting to http://localhost:8080/_lambda_ or http://localhost:8081/_lambda_ depending on whether you are in dev or test mode. Sending raw API Gateway HTTP events is a great way to test AWS security locally.

Anyways, I hope you all like this support. I’m very curious how what I’ve done compares to running locally with SAM CLI. Is it better? Worse? Needs a few more tweaks? Hope to hear from you soon.