README.md

bookmarkit - Quarkus coding dojo

You can use the docker-compose.yml file located on the root of this repository to launch all dependencies.

So going inside the root directory and launching the following command will get you up and running :)

docker-compose up

There is a Postman collection that can help to test your application during you developement, it is located here.

Step 1 - Quarkus basics

Goal: implements a bookmark service that pass the test from fr.loicmathieu.bookmarkit.BookmarkResourceTest.

Steps:

• Open bookmark-service inside your favorite IDE
• Implements the fr.loicmathieu.bookmarkit.BookmarkResource service, it's a classical CRUD service to allow to create/read/update/delete a bookmark. You must implement the service as a JAX-RS resource (WRITING JSON REST SERVICES). You must use Hibernate ORM with Panache to access the database (SIMPLIFIED HIBERNATE ORM WITH PANACHE).
• Run the service with mvn compile quarkus:dev it has live reload !
• Test that everything works with mvn test -Dtest=BookmarkResourceTest.

NOTE: Hibernate is configured to drop and recreate the schema each time you restart your application. You can change this behavior inside your application.properties.

Step 2 - Observability: OpenAPI, OpenMetrics and Health

Goal: implements Observability principles: metrology, health and discoverability

Steps:

• Add OpenAPI annotations to document your API, it will be available at http://localhost:8080/openapi and there is an embedded swagger UI at http://localhost:8080/swagger-ui
  • Use @Operation to document each operation.
• Add OpenMetrics annotations to create metrics for each method of your endpoints, you should provide counted and timed metrics via @Counted and @Timed, be careful that the name of the metric must be unique. You can access your metrics at http://localhost:8080/metrics.
• See that an health check is available at http://localhost:8080/health.
• Create a custom check

@Readiness
public class AppHealthCheck implements HealthCheck {

    @Override
    public HealthCheckResponse call() {
        return HealthCheckResponse.builder().name("bookmark").withData("is", "always").up().build();
    }
}

• Test that everything works with mvn test -Dtest=BookmarkObservabilityTest.

NOTE: OpenAPI and OpenMetrics works as soon as you integrate the extension inside your application as it provides default documentation and metrics. Health provides basic liveness and readiness checks, you can add your own if needed.

Step 3 - Configuration

Goal: understand how we can configure the application: Application Configuration.

Steps:

• Add a configuration property inside you application.properties file: greeting=World
• Modify BookmarkResource to read this configuration property and log it at startup:
  • Use @ConfigProperty to inject the property inside a greeting variable.
  • Create a @PostConstruct method that log it via LOGGER.infof("Hello %s", greeting) using Jboss logging.
• Test using mvn quarkus:dev you should see Hello World in the console.
• Add a new line to application.properties file: %dev.greeting=Dev this is an override of the same property for the dev profile.
• Test using mvn quarkus:dev you should see Hello Dev in the console.

NOTE: you must call the endpoint to initialize it so the method annotated by @PostConstructruns.

Step 4 - Run you app inside a container

Goal: understand how to build your application, package it in a container, configure it and run it.

Steps:

• Package your application with mvn package -DskipTests
• Run your application with java -jar target/bookmark-service-1.0-SNAPSHOT-runner.jar
• Limit it's Heap memory with java -Xmx32m -jar target/bookmark-service-1.0-SNAPSHOT-runner.jar (you can go lower but your apps will be slower)
• Override it's configuration from the command line with java -Dgreeting=JAR -jar target/bookmark-service-1.0-SNAPSHOT-runner.jar
• Build a docker image with docker build -f src/main/docker/Dockerfile.jvm -t bookmarkit .
• Run it with docker run -ti -p 8080:8080 -e "QUARKUS_DATASOURCE_URL=jdbc:postgresql://{your_ip}:5432/mydatabase" bookmarkit (replace {your_ip} by your ip).

Step 5 - Send a message via AMQP for each created bookmark

Goal: implements asynchronous messaging via AMQP

Steps:

• Uncomment the commented dependency quarkus-smallrye-reactive-messaging-amqp inside the pom.xml file.
• Configure AMQP inside your application.properties

amqp-username=quarkus
amqp-password=quarkus

• Configure MicroProfile messaging inside your application.properties

mp.messaging.outgoing.bookmarks.connector=smallrye-amqp
mp.messaging.outgoing.bookmarks.address=bookmarks
mp.messaging.outgoing.bookmarks.durable=true

• Inject an Emitter inside your BookmarkResource : @Inject @Stream("bookmarks") Emitter<Bookmark> emitter;
• Use this emitter to send the bookmark inside the create() method.
• Launch the consumer from bookmark-message-consumer via mvn compile quarkus:dev in an other console
• Create some bookmarks, you should see a line in the console of bookmark-message-consumer for each creation

Step 6 - Call an external service reliability

Goal: learn how to call an external REST service via MicroProfile RestClient and use the fault-tolerance capabilities to make it reliable

Steps:

• Uncomment the commented dependencies quarkus-rest-client and quarkus-smallrye-fault-tolerance inside the pom.xml file.
• Create an interface annotated with Jax-rs annotations to call the webservice TODO
• Inject it inside the BookmarkResource with the @RestClient annotation
• Use it to make a call to the ws each time a bookmark is created
• Test it multiple times, you should see that it crash half of the time
• Add fault-tolerance @Retry annotation to retry the call
• Test it again multiple times, it should work now :)