diff --git a/docs/src/main/asciidoc/extension-writing-dev-service.adoc b/docs/src/main/asciidoc/extension-writing-dev-service.adoc new file mode 100644 index 00000000000000..1afb950e9b3449 --- /dev/null +++ b/docs/src/main/asciidoc/extension-writing-dev-service.adoc @@ -0,0 +1,123 @@ +//// +This document is maintained in the main Quarkus repository +and pull requests should be submitted there: +https://github.com/quarkusio/quarkus/tree/main/docs/src/main/asciidoc +//// +[id="extension-writing-dev-service"] += Writing a dev service +include::_attributes.adoc[] +:categories: writing-extensions +:diataxis-type: howto +:topics: extensions +//// +//// + + +== Prerequisites + +- You should already have an xref:building-my-first-extension.adoc[extension structure] in place +- You should have a containerised version of your external service (not all dev services rely on containers, but most do) + +== Creating a dev service + +If your extension provides APIs for connecting to an external service, it's a good idea to provide a xref:dev-services.adoc[dev service] implementation. + +To create a dev service, add a new build step into the extension processor class that returns a `DevServicesResultBuildItem`. +Here, the link:https://hub.docker.com/_/hello-world`hello-world` image is used, but you should set up the right image for your service. + +[source%nowrap,java] +---- + @BuildStep(onlyIfNot = IsNormal.class, onlyIf = GlobalDevServicesConfig.Enabled.class) { + public DevServicesResultBuildItem createContainer() { + DockerImageName dockerImageName = DockerImageName.parse("hello-world"); + GenericContainer container = new GenericContainer<>(dockerImageName) + .withExposedPorts(SERVICE_PORT, OTHER_SERVICE_PORT) + .waitingFor(Wait.forLogMessage(".*" + "Started" + ".*", 1)) + .withReuse(true); + + container.start(); + + String newUrl = "http://" + container.getHost() + ":" + container.getMappedPort(SERVICE_PORT); + Map configOverrides = Map.of("some-service.base-url", newUrl); + + return new DevServicesResultBuildItem.RunningDevService(FEATURE, container.getContainerId(), + container::close, configOverrides) + .toBuildItem(); + } +---- + +With this code, you should be able to see your container starting if you add your extension to a test application and run `quarkus dev`. +However, the application will not be able to connect to it, because no ports are exposed. To expose ports, add `withExposedPorts` to the container construction. +For example, + +[source%nowrap,java] +---- +GenericContainer container = new GenericContainer<>(dockerImageName) + .withExposedPorts(SERVICE_PORT, OTHER_SERVICE_PORT); +---- + +Testcontainers will map these ports to random ports on the host. This avoids port conflicts, but presents a new problem – how do applications connect to the service in the container? + +To allow applications to connect, the extension should override the default configuration for the service with the mapped ports. +This must be done after starting the container. +For example, + +[source%nowrap,java] +---- + container.start(); + Map configOverrides = Map.of("some-service.base-url", + "http://" + container.getHost() + ":" + container.getMappedPort(SERVICE_PORT)); +---- + +Other configuration overrides may be included in the same map. + +== Waiting for the container to start + +You should add a `.waitingFor` call to the container construction, to wait for the container to start. For example + +[source%nowrap,java] +---- + .waitingFor(Wait.forLogMessage(".*" + "Started" + ".*", 1)) +---- + +Waiting for a port to be open is another option. See the link:https://java.testcontainers.org/features/startup_and_waits/[Testcontainers documentation] for a full discussion of wait strategies. + +== Configuring the dev service + +To configure the dev service launch process, your build step can accept a `ConfigPhase.BUILD_TIME` config class in its constructor. +For example, + +[source%nowrap,java] +---- + @BuildStep(onlyIfNot = IsNormal.class, onlyIf = GlobalDevServicesConfig.Enabled.class) { + public DevServicesResultBuildItem createContainer(MyConfig config) { +---- + +You may wish to use this config to set a fixed port, or set an image name, for example. + +[source%nowrap,java] +---- + if (config.port.isPresent()) { + container.setPortBindings(List.of(config.port.get() + ":" + SERVICE_PORT)); + } +---- + +== Controlling re-use + +In dev mode, with hot reload, Quarkus may restart frequently. By default, this will also restart test containers. +Quarkus restarts are usually very fast, but containers may take much longer to restart. +To prevent containers restarting on every code change, you can mark the container as reusable: + +[source%nowrap,java] +---- + .withReuse(true) +---- + +Some dev services implement sophisticated reuse logic in which they track the state of the container in the processor itself. +You may need this if your service has more complex requirements, or needs sharing across instances. + + +== References + +- xref:dev-services.adoc[Dev services overview] +- xref:writing-extensions.adoc[Guide to writing extensions] diff --git a/docs/src/main/asciidoc/writing-extensions.adoc b/docs/src/main/asciidoc/writing-extensions.adoc index bdee927dfb80bd..e5f7af44acbddd 100644 --- a/docs/src/main/asciidoc/writing-extensions.adoc +++ b/docs/src/main/asciidoc/writing-extensions.adoc @@ -1978,6 +1978,12 @@ in your runtime module, and add a `META-INF/services/io.quarkus.dev.spi.HotRepla On startup the `setupHotDeployment` method will be called, and you can use the provided `io.quarkus.dev.spi.HotReplacementContext` to initiate a scan for changed files. +==== Dev services + +Where extensions use an external service, adding dev service can improve the user experience in development and test modes. +See xref:extension-writing-dev-service.adoc[how to write a dev service] for more details. + + === Testing Extensions Testing of Quarkus extensions should be done with the `io.quarkus.test.QuarkusUnitTest` JUnit 5 extension.