kindcontainer

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Kindcontainer

A Java-based testcontainers.org container implementation that uses Kubernetes in Docker (KIND) to provide ephemeral Kubernetes clusters for unit/integration testing.

Container Flavors

The Kindcontainer libraries offers three different Kubernetes container implementations:

• ApiServerContainer
• K3sContainer
• KindContainer

While ApiServerContainer (as the name suggests) starts only a Kubernetes Api Server (plus the required) etcd in the background, both K3sContainer and KindContainer are feature rich Kubernetes containers that can e.g. spin up Pods and even provision PersistentVolumes.

Usage

Add dependency

First you need to add the Kindcontainer dependency to your build. Kindcontainer is available on maven central.

Maven

Add the Kindcontainer dependency:

<project>
    <dependencies>
        <dependency>
            <groupId>com.dajudge.kindcontainer</groupId>
            <artifactId>kindcontainer</artifactId>
            <version>1.3.0</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

Gradle

Add the Kindcontainer dependency:

repositories {
    mavenCentral()
}

dependencies {
    testImplementation "com.dajudge.kindcontainer:kindcontainer:1.3.0"
}

Use in JUnit test

With KindContainer

public class SomeKindTest {
    @ClassRule
    public static final KindContainer<?> KUBE = new KindContainer<>();

    @Test
    public void verify_node_is_present() {
        // Create a fabric8 client and use it!
        try(final KubernetesClient client = new DefaultKubernetesClient(fromKubeconfig(KUBE.getKubeconfig()))) {
            assertEquals(1, client.nodes().list().getItems().size());
        }
    }
}

Look here for the reference test.

With K3sContainer

public class SomeK3sTest {
    @ClassRule
    public static final K3sContainer<?> K3S = new K3sContainer<>();

    @Test
    public void verify_node_is_present() {
        // Create a fabric8 client and use it!
        try(final KubernetesClient client = new DefaultKubernetesClient(fromKubeconfig(K3S.getKubeconfig()))) {
            assertEquals(1, client.nodes().list().getItems().size());
        }
    }
}

Look here for the reference test.

With ApiServerContainer

If you don't need a full-fledged Kubernetes distribution for your testing, using the ApiServerContainer might be an option for you that shaves off a lot of the startup overhead of the KindContainer. The ApiServerContainer only starts an etcd instance and a Kubernetes API-Server, can be more than enough e.g. if all you want to test is if your custom operator handles it's CRDs properly or creates the required objects in the control plane.

public class SomeApiServerTest {
    @ClassRule
    public static final ApiServerContainer<?> KUBE = new ApiServerContainer<>();

    @Test
    public void verify_no_node_is_present() {
        // Create a fabric8 client and use it!
        try (final KubernetesClient client = new DefaultKubernetesClient(fromKubeconfig(KUBE.getKubeconfig()))) {
            assertTrue(client.nodes().list().getItems().isEmpty());
        }
    }
}

Look here for the reference test.

Examples

You can find examples in the kindcontainer-examples repository.