Custom dev-Service for Quarkus

I am creating a web service using Quarkus as framework, which uses another web service. I thought it would be nice to use the same dev service mechanism, which quarkus uses for databasesm, etc. to start up a container containing this other service (or a mock service of it).

I was able to achieve this for JUnit testing with implementing a class of QuarkusTestResourceLifecycleManager:

        // Create the Image
        ImageFromDockerfile image = new ImageFromDockerfile()...
        // Create the Container
        GenericContainer<?> container = new GenericContainer<>(image)...
        // Start the Container
        container.start();

Now I would like to use the same container in dev mode. Ideally as dev service, which is also shown in the devUI.

What is the best practice for that? Is there any documentation on the API, which I did not find?

For this, you'd need to write an extension for the other web service. Quarkus have a few resources about writing extensions:

• My first extension
• Deeper guide
• A walkthough of writing a logging extension

To scaffold an extension, you'd run something like

mvn io.quarkus.platform:quarkus-maven-plugin:3.2.0.Final:create-extension -N \
    -DgroupId=org.acme \ 
    -DextensionId=other-web-service

Once you have your skeleton extension, the code to add a dev service is pretty compact. In the processor, you need to add a build step producing a build item of type 'dev services'. The build items are a bit like the API for extensions, and you can achieve most things you want just by constructing and returning a build item of the right kind.

    @BuildStep(onlyIfNot = IsNormal.class, onlyIf = GlobalDevServicesConfig.Enabled.class)
    public DevServicesResultBuildItem createContainer(LaunchModeBuildItem launchMode) {

        DockerImageName dockerImageName = DockerImageName.parse("namespace/other-web-service");
        
        // You might want to use Quarkus config here to customise the container
        OtherWebServiceContainer container = new OtherWebServiceContainer()
                .withEnv("whatever", "true")
                .withEnv("otherenv", "something")
                
        container.start();

        Map<String, String> props = Map.of("mynew.url",
                "https://" + container.getHost() + ":" + container.getPort());
        return new DevServicesResultBuildItem.RunningDevService(FEATURE, container.getContainerId(),
                container::close, props)
                .toBuildItem();
    }

    private static class OtherWebServiceContainer extends GenericContainer<OtherWebServiceContainer> {
        static final int PORT = 25565;

        public OtherWebServiceContainer(DockerImageName image) {
            super(image);
        }

        @Override
        protected void configure() {
            withNetwork(Network.SHARED);
            addExposedPorts(PORT);
            // Tell the dev service how to know the container is ready
            waitingFor(Wait.forLogMessage(".*Listening on http://0.0.0.0:9292.*", 1)); 
        }

        public Integer getPort() {
            return this.getMappedPort(PORT);
        }
    }

If you get stuck, looking through the Quarkus codebase for examples of how dev services are created should give you ideas.