Add pod ephemeral containers operations

[cronik]

Discussed in #4743

^{Originally posted by cronik January 7, 2023}
Is it possible to call the EphemeralContainers Operations on a Pod resource?

PATCH /api/v1/namespaces/{namespace}/pods/{name}/ephemeralcontainers

It does not appear to be supported directly in the dsl api, but I'm wondering if there is some workaround that might allow me to call the patch operation (maybe by constructing a operations context or something).

Are there plans to support these operations in the dsl? I'd be happy to contribute a PR if it will be welcomed.

Proposed API

Ephemeral containers operations supports PATCH and REPLACE as sub resource of Pod. I propose a new EphemeralContainersResource that exposes the operations supported on this resource.

interface PodResource {
  // ...
  EphemeralContainersResource ephemeralContainers();
}

interface EphemeralContainersResource extends EditReplacePatchable<Pod> { }

class PodOperationsImpl implements EphemeralContainersResource {
    EphemeralContainersResource ephemeralContainers() {
        return new PodOperationsImpl(getContext(), context.withSubresource("ephemeralcontainers"));
    }
}

Example client usage

PodResource resource = client.pods().withName("pod-standard");
resource.ephemeralContainers()
  .edit(p -> new PodBuilder(p)
    .editSpec()
    .addNewEphemeralContainer()
    .withName("debugger-3")
    .withImage("busybox")
    .withCommand("sleep", "36000")
    .endEphemeralContainer()
    .endSpec()
    .build());

resource.waitUntilCondition(p -> {
  return p.getStatus()
      .getEphemeralContainerStatuses()
      .stream()
      .filter(s -> s.getName().equals("debugger-3"))
      .anyMatch(s -> s.getState().getRunning() != null);
  }, 2, TimeUnit.MINUTES);

ByteArrayOutputStream out = new ByteArrayOutputStream();
try (ExecWatch watch = resource.inContainer("debugger-3")
  .writingOutput(out)
  .exec("sh", "-c", "echo 'hello world!'")) {
  assertEquals(0, watch.exitCode().join());
  assertEquals("hello world!", out.toString());
}

https://kubernetes.io/docs/concepts/workloads/pods/ephemeral-containers/