docker_container: cgroup_parent (#59)

* Document that the Docker SDK for Python is used by the module.

* Allow to specify cgroup_parent for container.

plugins/doc_fragments/docker.py

@@ -111,6 +111,9 @@ notes:
 
     DOCKER_PY_1_DOCUMENTATION = r'''
 options: {}
+notes:
+  - This module uses the L(Docker SDK for Python,https://docker-py.readthedocs.io/en/stable/) to
+    communicate with the Docker daemon.
 requirements:
   - "Docker SDK for Python: Please note that the L(docker-py,https://pypi.org/project/docker-py/)
      Python module has been superseded by L(docker,https://pypi.org/project/docker/)
@@ -127,6 +130,9 @@ requirements:
 
     DOCKER_PY_2_DOCUMENTATION = r'''
 options: {}
+notes:
+  - This module uses the L(Docker SDK for Python,https://docker-py.readthedocs.io/en/stable/) to
+    communicate with the Docker daemon.
 requirements:
   - "Python >= 2.7"
   - "Docker SDK for Python: Please note that the L(docker-py,https://pypi.org/project/docker-py/)

plugins/modules/docker_container.py

@@ -52,6 +52,11 @@ options:
       - List of capabilities to drop from the container.
     type: list
     elements: str
+  cgroup_parent:
+    description:
+      - Specify the parent cgroup for the container.
+    type: str
+    version_added: 1.1.0
   cleanup:
     description:
       - Use with I(detach=false) to remove the container after successful execution.
@@ -1596,6 +1601,7 @@ class TaskParameters(DockerBaseClass):
             publish_all_ports='publish_all_ports',
             links='links',
             privileged='privileged',
+            cgroup_parent='cgroup_parent',
             dns='dns_servers',
             dns_opt='dns_opts',
             dns_search='dns_search_domains',
@@ -2190,6 +2196,7 @@ class Container(DockerBaseClass):
             interactive=config.get('OpenStdin'),
             capabilities=host_config.get('CapAdd'),
             cap_drop=host_config.get('CapDrop'),
+            cgroup_parent=host_config.get('CgroupParent'),
             expected_devices=host_config.get('Devices'),
             dns_servers=host_config.get('Dns'),
             dns_opts=host_config.get('DnsOptions'),
@@ -3389,6 +3396,7 @@ def main():
         blkio_weight=dict(type='int'),
         capabilities=dict(type='list', elements='str'),
         cap_drop=dict(type='list', elements='str'),
+        cgroup_parent=dict(type='str'),
         cleanup=dict(type='bool', default=False),
         command=dict(type='raw'),
         comparisons=dict(type='dict'),