Add k8s_exec module to execute command through the API

This change adds a new module to execute command in a container
through the API:
https://docs.okd.io/latest/dev_guide/executing_remote_commands.html#protocol

lib/ansible/modules/clustering/k8s/k8s_exec.py

@@ -0,0 +1,112 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# (c) 2019, Red Hat
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import absolute_import, division, print_function
+
+__metaclass__ = type
+
+
+ANSIBLE_METADATA = {'metadata_version': '1.1',
+                    'status': ['preview'],
+                    'supported_by': 'community'}
+
+DOCUMENTATION = '''
+
+module: k8s_exec
+
+short_description: Execute command in Pod
+
+version_added: "2.9"
+
+author: "Tristan de Cacqueray"
+
+description:
+  - Use the Kubernetes Python client to execute command on K8s pods.
+
+requirements:
+  - "python >= 2.7"
+  - "openshift == 0.4.3"
+  - "PyYAML >= 3.11"
+'''
+
+EXAMPLES = '''
+- name: Execute a command
+  k8s_exec:
+    namespace: myproject
+    pod: zuul-scheduler
+    command: zuul-scheduler full-reconfigure
+'''
+
+RETURN = '''
+result:
+  description:
+  - The command object
+  returned: success
+  type: complex
+  contains:
+     stdout:
+       description: The command stdout
+       type: str
+     stdout_lines:
+       description: The command stdout
+       type: str
+     stderr:
+       description: The command stderr
+       type: str
+     stderr_lines:
+       description: The command stderr
+       type: str
+'''
+
+import copy
+import shlex
+from ansible.module_utils.k8s.common import KubernetesAnsibleModule
+from ansible.module_utils.k8s.common import AUTH_ARG_SPEC, COMMON_ARG_SPEC
+
+from kubernetes.client.apis import core_v1_api
+from kubernetes.stream import stream
+
+
+class KubernetesExecCommand(KubernetesAnsibleModule):
+    @property
+    def argspec(self):
+        spec = copy.deepcopy(COMMON_ARG_SPEC)
+        spec.update(copy.deepcopy(AUTH_ARG_SPEC))
+        for k in ('kind', 'state', 'force', 'resource_definition', 'src'):
+            del spec[k]
+        spec['pod'] = {'type': 'str'}
+        spec['command'] = {'type': 'str'}
+        return spec
+
+
+def main():
+    module = KubernetesExecCommand()
+    # Load kubernetes.client.Configuration
+    module.get_api_client()
+    api = core_v1_api.CoreV1Api()
+    resp = stream(
+        api.connect_get_namespaced_pod_exec,
+        module.params["pod"],
+        module.params["namespace"],
+        command=shlex.split(module.params["command"]),
+        stdout=True,
+        stderr=True,
+        stdin=False,
+        tty=False,
+        _preload_content=False)
+    stdout, stderr = [], []
+    while resp.is_open():
+        resp.update(timeout=1)
+        if resp.peek_stdout():
+            stdout.append(resp.read_stdout())
+        if resp.peek_stderr():
+            stderr.append(resp.read_stderr())
+    module.exit_json(
+        changed=True, stdout="".join(stdout), stderr="".join(stderr))
+
+
+if __name__ == '__main__':
+    main()