Add Exec command to Pods

[pablochacin]

Add function for executing a command in an existing pod and return the output (stdin and strerr) in a similar way than executing a non interactive command using kubectl exec

Note: for implementing this functionality it is necessary to access the k8s client configuration. As the client library does not allow to retrieve it from the client instance, it was necessary to add the config to the Pod structure.

Closes #35

[ppcano]

@pablochacin

Reviewing the example from a user perspective, it would be ideal to skip passing the container name.

What makes me think if we could pass the pod directly , so either the podName or the pod.

kubernetes.pods.exec({
  pod: pod,
  command:[]
  stadin: []
});

[pablochacin]

Pods can have multiple containers, so it is important that the API allows specifying the target container.

For example, when using ephemeral containers to add chaos behavior to a running pod, it is necessary to be able to execute commands in the ephemeral container.

What could be improved is to mimic the behavior of the kubectl command and chose a default container if none is specified.

[dgzlopes]

What could be improved is to mimic the behavior of the kubectl command and chose a default container if none is specified.

Personally, I never liked this behavior :(

So, I would keep it as it is right now.

[ppcano]

posted a code comment

[ppcano]

cc @javaducky

[javaducky]

LGTM