[Suggestion] Add extraPortMapping between the container and the host

[cmoulliard]

Suggestion

Some use cases require to add extraPortMapping between the container and the host. This is typically the case when we install an ingress controller exposing routes: argocd.localtest.me:8443, argocd.127.0.0.1.nip.io, etc

Kind supports such an option using

kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
nodes:
- role: control-plane
  image: "kindest/node:v1.31.4"
  labels:
    ingress-ready: "true"
  extraPortMappings:
  - containerPort: 443
    hostPort: 8443
    protocol: TCP
...

Implementation: https://github.com/kubernetes-sigs/kind/blob/5f59a835fa1da606f7709ef51827467f53f8f091/pkg/cluster/internal/providers/podman/provision.go#L100

Such a feature is offered by the Generic TestContainer but protected !!!

// https://github.com/testcontainers/testcontainers-java/blob/main/core/src/main/java/org/testcontainers/containers/GenericContainer.java#L1130-L1148

    /**
     * Add a container port that should be bound to a fixed port on the docker host.
     * <p>
     * Note that this method is protected scope to discourage use, as clashes or instability are more likely when
     * using fixed port mappings. If you need to use this method from a test, please use {@link FixedHostPortGenericContainer}
     * instead of GenericContainer.
     *
     * @param hostPort
     * @param containerPort
     * @param protocol
     */
    protected void addFixedExposedPort(int hostPort, int containerPort, InternetProtocol protocol) {
        ExposedPort exposedPort = new ExposedPort(
            containerPort,
            com.github.dockerjava.api.model.InternetProtocol.parse(protocol.name())
        );
        PortBinding portBinding = new PortBinding(Ports.Binding.bindPort(hostPort), exposedPort);
        this.containerDef.addPortBindings(portBinding);
    }

[dajudge]

Hi @cmoulliard,

thanks for bringing up this use-case!

Looking at #363 and #357 there seems to be a pattern evolving of changes that allow modification of the kubeadm config. Maybe it'd be a good time to think about a more generic solution here like giving the user the opportunity to modify the kubeadm config before it's copied to the container?

We could e.g. introduce a callback that provides the raw string of the config to the user who then can modify it to their likings and we continue with the modified version.

Would that address your needs?

That way we would gain maximum flexibility and be future-proof without requiring additional functionality in the kindcontainer library for each feature the kubeadm config offers.

WDYT?

[cmoulliard]

Maybe it'd be a good time to think about a more generic solution here like giving the user the opportunity to modify the kubeadm config before it's copied to the container?

We need something more generic by the way able not only to configure kubeAdm.

When you use the kind go tool, the kindConfig file will help you to configure:

• The container to be created (ports, volumes, networks, etc) top of docker or podman
• kubeAdm using the field kubeadmConfigPatches - https://kind.sigs.k8s.io/docs/user/configuration/#kubeadm-config-patches

[cmoulliard]

We could e.g. introduce a callback that provides the raw string of the config to the user who then can modify it to their likings and we continue with the modified version.

How could we setup such a callback as this project is used as lib or packaged also as lib part of quarkus ?

[dajudge]

Port exposure is already available through the inherited Testcontainers GenericContainer API:

KindContainer<?> kind = new KindContainer<>()
        .withExposedPorts(443);

kind.start();
int httpsPort = kind.getMappedPort(443);

For example, an ingress can then be reached through https://argocd.localtest.me: plus the mapped port.

A dedicated fixed-host-port API would encourage port collisions between parallel tests and existing host processes, which is why Testcontainers deliberately discourages fixed mappings. The dynamic mapping above provides the required host access, so I’m closing this as already supported.