Add k8s_exec module to collection

[geerlingguy]

SUMMARY

A new k8s_exec module would allow execution of command in a pod container through the API:
https://docs.okd.io/latest/dev_guide/executing_remote_commands.html#protocol

See: ansible/ansible#55029

Currently the only easy way to do this (without using a custom module) is via kubectl and the command or shell module, which requires more dependencies and setup, and is more fragile.

ISSUE TYPE

• Feature Idea

COMPONENT NAME

k8s_exec

ADDITIONAL INFORMATION

Example playbook:

- hosts: localhost
  gather_facts: no
  vars:
    pod: example-sf-zuul-scheduler-84bf645594-kw9lr
    namespace: myproject
  tasks:
    - name: Test Exec
      k8s_exec:
        pod: "{{ pod }}"
        namespace: "{{ namespace }}"
        command: zuul --version

    - name: Test Stderr
      k8s_exec:
        pod: "{{ pod }}"
        namespace: "{{ namespace }}"
        command: sh -c "echo toto > /dev/stderr"

Results in:

$ ansible-playbook -v test-exec.yaml
PLAY [localhost] *************************************************************

TASK [Test Exec] *************************************************************
changed: [localhost] => {
  "changed": true, "stderr": "", "stderr_lines": [],
  "stdout": "Zuul version: 3.7.2.dev37\n",
  "stdout_lines": ["Zuul version: 3.7.2.dev37"]
}

TASK [Test Stderr] ***********************************************************
changed: [localhost] => {
  "changed": true, "stderr": "toto\n", "stderr_lines": ["toto"],
  "stdout": "", "stdout_lines": []
}

PLAY RECAP *******************************************************************
localhost                  : ok=2    changed=2    unreachable=0    failed=0