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Superheroes Event Statistics Microservice

Table of Contents

Quality Gate Status Reliability Rating Maintainability Rating Security Rating Coverage Lines of Code

Introduction

This is the event statistics microservice. It is an event-driven microservice, listening for fight event messages on an Apache Kafka topic utilizing SmallRye Reactive Messaging.

event-statistics

Messages arrive on the fights topic. The SuperStats class listens to these events and keeps track of 2 kinds of statistics: team stats and winner stats.

Messages are stored in Apache Avro format and the fight schema is automatically registered in the Apicurio Schema Registry. This all uses built-in extensions from Quarkus.

This service also has its own UI where you can see the top winners and the percentage of hero victories!

event-statistics-ui

Team Stats

Team stats are accumulated by the number of wins by heroes vs villains. It is calculated as a percentage of hero wins to villain wins.

Team stats are then sent over the /stats/team WebSocket by the TeamStatsWebSocket WebSocket class. Every time a new fight event is received, the team stats are re-computed and a JSON structure is emitted to anyone listening on the WebSocket.

A sample payload might look like this:

{
    "heroWins": 15,
    "villainWins": 5,
    "numberOfFights": 20,
    "heroWinRatio": 0.75
}

Winner Stats

Winner stats are accumulated by the number of wins of each hero or villain.

Winner stats are then sent over the /stats/winners WebSocket by the TopWinnerWebSocket WebSocket class. Every time a new fight event is received, the winner stats are re-computed and a JSON array containing all the winners and the number of wins for each winner is emitted to anyone listening on the WebSocket.

A sample payload might look like this:

[
    {
        "name": "Chewbacca",
        "score": 5
    },
    {
        "nane": "Darth Vader",
        "score": 3
    },
    {
        "name": "Yoda",
        "score": 10
    }
]

Testing

This application has a full suite of tests, including an integration test suite (TeamStatsWebSocketIT and TopWinnerWebSocketIT). The integration test suite uses Quarkus Dev Services (see KafkaProducerResource) to interact with a Kafka instance. Integration tests can inject a KafkaProducer to place messages on the topic and then listen on the WebSockets to verify stats were correctly computed.

Running the Application

The application runs on port 8085 (defined by quarkus.http.port in application.properties).

From the quarkus-super-heroes/event-statistics directory, simply run ./mvnw quarkus:dev to run Quarkus Dev Mode, or running quarkus dev using the Quarkus CLI. The application's UI will be exposed at http://localhost:8085 and the Quarkus Dev UI will be exposed at http://localhost:8085/q/dev. Quarkus Dev Services will ensure an Apache Kafka instance and an Apicurio Schema Registry are started and configured.

NOTE: Running the application outside of Quarkus dev mode requires standing up an Apache Kafka instance and an Apicurio Schema Registry and binding it to the app.

By default, the application is configured with the following:

Description Environment Variable Java Property Value
Kafka Bootstrap servers KAFKA_BOOTSTRAP_SERVERS kafka.bootstrap.servers PLAINTEXT://localhost:9092
Apicurio Schema Registry MP_MESSAGING_CONNECTOR_SMALLRYE_KAFKA_APICURIO_REGISTRY_URL mp.messaging.connector.smallrye-kafka.apicurio.registry.url http://localhost:8086/apis/registry/v2

Running Locally via Docker Compose

Pre-built images for this application can be found at quay.io/quarkus-super-heroes/event-statistics.

Pick one of the 4 versions of the application from the table below and execute the appropriate docker compose command from the quarkus-super-heroes/event-statistics directory.

Note

You may see errors as the applications start up. This may happen if an application completes startup before one if its required services (i.e. database, kafka, etc). This is fine. Once everything completes startup things will work fine.

Description Image Tag Docker Compose Run Command
JVM Java 21 java21-latest docker compose -f deploy/docker-compose/java21.yml up --remove-orphans
Native native-latest docker compose -f deploy/docker-compose/native.yml up --remove-orphans

These Docker Compose files are meant for standing up this application and the required Kafka broker only. If you want to stand up the entire system, follow these instructions.

Once started the application will be exposed at http://localhost:8082. The Apicurio Schema Registry will be exposed at http://localhost:8086.

Deploying to Kubernetes

The application can be deployed to Kubernetes using pre-built images or by deploying directly via the Quarkus Kubernetes Extension. Each of these is discussed below.

Using pre-built images

Pre-built images for this application can be found at quay.io/quarkus-super-heroes/event-statistics.

Deployment descriptors for these images are provided in the deploy/k8s directory. There are versions for OpenShift, Minikube, Kubernetes, and Knative.

Note

The Knative variant can be used on any Knative installation that runs on top of Kubernetes or OpenShift. For OpenShift, you need OpenShift Serverless installed from the OpenShift operator catalog. Using Knative has the benefit that services are scaled down to zero replicas when they are not used.

Pick one of the 4 versions of the application from the table below and deploy the appropriate descriptor from the deploy/k8s directory.

Description Image Tag OpenShift Descriptor Minikube Descriptor Kubernetes Descriptor Knative Descriptor
JVM Java 21 java21-latest java21-openshift.yml java21-minikube.yml java21-kubernetes.yml java21-knative.yml
Native native-latest native-openshift.yml native-minikube.yml native-kubernetes.yml native-knative.yml

The application is exposed outside of the cluster on port 80.

These are only the descriptors for this application and the required Kafka broker and Apicurio Schema Registry only. If you want to deploy the entire system, follow these instructions.

Deploying directly via Kubernetes Extensions

Following the deployment section of the Quarkus Kubernetes Extension Guide (or the deployment section of the Quarkus OpenShift Extension Guide if deploying to OpenShift), you can run one of the following commands to deploy the application and any of its dependencies (see Kubernetes (and variants) resource generation of the automation strategy document) to your preferred Kubernetes distribution.

Note

For non-OpenShift or minikube Kubernetes variants, you will most likely need to push the image to a container registry by adding the -Dquarkus.container-image.push=true flag, as well as setting the quarkus.container-image.registry, quarkus.container-image.group, and/or the quarkus.container-image.name properties to different values.

Target Platform Java Version Command
Kubernetes 21 ./mvnw clean package -Dquarkus.profile=kubernetes -Dquarkus.kubernetes.deploy=true -DskipTests
OpenShift 21 ./mvnw clean package -Dquarkus.profile=openshift -Dquarkus.container-image.registry=image-registry.openshift-image-registry.svc:5000 -Dquarkus.container-image.group=$(oc project -q) -Dquarkus.kubernetes.deploy=true -DskipTests
Minikube 21 ./mvnw clean package -Dquarkus.profile=minikube -Dquarkus.kubernetes.deploy=true -DskipTests
Knative 21 ./mvnw clean package -Dquarkus.profile=knative -Dquarkus.kubernetes.deploy=true -DskipTests
Knative (on OpenShift) 21 ./mvnw clean package -Dquarkus.profile=knative-openshift -Dquarkus.container-image.registry=image-registry.openshift-image-registry.svc:5000 -Dquarkus.container-image.group=$(oc project -q) -Dquarkus.kubernetes.deploy=true -DskipTests

You may need to adjust other configuration options as well (see Quarkus Kubernetes Extension configuration options and Quarkus OpenShift Extension configuration options).

Tip

The do_build function in the generate-k8s-resources.sh script uses these extensions to generate the manifests in the deploy/k8s directory.