Quarkus Kafka Consumer Demo

This is a simple example of how to build a Kafka consumer with Quarkus and Tekton.

This demo implements a small Quarkus App that connects to a Kafka broker and receives a stream of events from a specific topic. Events are streamed as Server Sent Events and displayed on a web page via Angular asynchronous calls.

The "event" message is a JSon-formatted payload that contains

an unique UUID that identifies an event stream
a message string
an event severity index (integer)
the event timestamp

The kafka message key is set to be equal to the UUID contained in the payload.

Running the application in dev mode

You can run your application in dev mode that enables live coding using:

./mvnw compile quarkus:dev

Running the application in dev mode requires an already running Kafka Broker. A simple one-node broker running on localhost is enough. To install AMQ Streams on a RedHat Enterprise Linux 8 server, refer to this Ansible Playbook.

NOTE: Quarkus now ships with a Dev UI, which is available in dev mode only at http://localhost:8080/q/dev/.

Packaging and running the application

The application can be packaged using:

./mvnw package

It produces the quarkus-run.jar file in the target/quarkus-app/ directory. Be aware that it’s not an über-jar as the dependencies are copied into the target/quarkus-app/lib/ directory.

The application is now runnable using java -jar target/quarkus-app/quarkus-run.jar.

If you want to build an über-jar, execute the following command:

./mvnw package -Dquarkus.package.type=uber-jar

The application, packaged as an über-jar, is now runnable using java -jar target/*-runner.jar.

Testing the application

Some simple automated tests are shipped as JUnit test cases. To run tests simply use maven:

./mvnw clean test

An embedded Kafka Cluster is automatically started as a Quarkus Resource for the Test Lifecycle Manager.

Creating a native executable

You can create a native executable using:

./mvnw package -Pnative

Or, if you don't have GraalVM installed, you can run the native executable build in a container using:

./mvnw package -Pnative -Dquarkus.native.container-build=true

You can then execute your native executable with: ./target/consumer-1.0.0-SNAPSHOT-runner

If you want to learn more about building native executables, please consult https://quarkus.io/guides/maven-tooling.html.

Building the artifact using Tekton on Openshift Container Platform

Please follow the steps described here to deploy the CI environment. The repo contains automation that deploys the CI env, the application manifests and the tektok pipeline used to build the app itself.

Related Guides

RESTEasy JAX-RS (guide): REST endpoint framework implementing JAX-RS and more
Kafka for JUnit (docs): Embedded Kafka for JUnit
Vert.x under Quarkus (docs): Use Vert.x under Quarkus reference docs
Quarkus Kafka Guide (docs): Guide for using Kafka under Quarkus

Provided Code

The application comes with a simple Angular frontend listening on the default quarkus HTTP server port:

mcaimi / kafka-event-consumer-demo