thorntail-on-kubernetes-example

Thorntail on Kubernetes

The purpose of this example is to demonstrate the following:

• How you can use the kubernetes-thorntail-starter.
• How Dekorate detects that this is a web app and automatically configures services.
• How you can end-to-end test the application.
• How you can trigger a Docker build after the compilation.

The application is using:

<dependency>
  <groupId>io.dekorate</groupId>
  <artifactId>kubernetes-thorntail-starter</artifactId>
  <version>${project.version}</version>
  <scope>provided</scope>
</dependency>

Which contains all the required modules, including the annotation processors that detect Thorntail web applications.

The RestApplication.class is annotated with @KubernetesApplication which triggers the resource generation. This annotation allows the user to trigger a Docker build after the compilation, by passing the system property dekorate.build=true to the build:

mvn clean install -Ddekorate.build=true

Note: Dekorate is not going to generate a Dockerfile for you. It expects to find one in the root of the module. It also expects to find the docker binary pointing to a running Docker daemon.

The Thorntail web application processor will detect our HelloResource.java, and will:

• Add container port 9090.
• Expose port 9090 as a service.

It will also add readiness and liveness probes, as configured in the @KubernetesApplication annotation.

Note that default port on which Thorntail web apps are exposed is 8080. Dekorate detected (in project-defaults.yml) that the app is configured to be exposed on 9090, and adjusted the configuration automatically.

Integration testing

For the purpose of integration testing, the example includes:

<dependency>
  <groupId>io.dekorate</groupId>
  <artifactId>kubernetes-junit-starter</artifactId>
  <version>${project.version}</version>
  <scope>test</scope>
</dependency>

This annotation will bring in the JUnit5 extension that Dekorate provides, that allows you to run integration tests via the '@KubernetesIntegrationTest' annotation. The integration test is ThorntailOnKubernetesIT.java and it demonstrates:

• How you can deploy the application for end to end testing.
• How use can use the Kubernetes client from within the test to connect to the application.

The test are going to be automatically run when building the application. For example:

mvn clean install

Note: To run the integration tests, an actual Kubernetes environment is required. As the integration test requires a Docker build to run, the tests will only run if an existing Dockerfile is found, and if the Docker daemon you are logged into is the one Kubernetes uses.