feat: add cgroup to host config--according to api docs (closes#2340)

docker/models/containers.py

@@ -570,6 +570,7 @@ def run(self, image, command=None, stdout=True, stderr=False,
                 ``["SYS_ADMIN", "MKNOD"]``.
             cap_drop (list of str): Drop kernel capabilities.
             cgroup_parent (str): Override the default parent cgroup.
+            cgroup (str): Cgroup to use for the container.
             cgroupns (str): Override the default cgroup namespace mode for the
                 container. One of:
                 - ``private`` the container runs in its own private cgroup

docker/types/containers.py

@@ -284,7 +284,7 @@ def __init__(self, version, binds=None, port_bindings=None,
                  nano_cpus=None, cpuset_mems=None, runtime=None, mounts=None,
                  cpu_rt_period=None, cpu_rt_runtime=None,
                  device_cgroup_rules=None, device_requests=None,
-                 cgroupns=None):
+                 cgroupns=None, cgroup=None):
 
         if mem_limit is not None:
             self['Memory'] = parse_bytes(mem_limit)
@@ -424,6 +424,10 @@ def __init__(self, version, binds=None, port_bindings=None,
         if cgroup_parent is not None:
             self['CgroupParent'] = cgroup_parent
 
+        if cgroup is not None:
+            if isinstance(cgroup, str):
+                self['Cgroup'] = cgroup
+
         if ulimits is not None:
             if not isinstance(ulimits, list):
                 raise host_config_type_error('ulimits', ulimits, 'list')

tests/unit/api_container_test.py

@@ -306,6 +306,20 @@ def test_create_container_with_cgroup_parent(self):
         assert 'CgroupParent' in data['HostConfig']
         assert data['HostConfig']['CgroupParent'] == 'test'
 
+    def test_create_container_with_cgroup(self):
+        self.client.create_container(
+            'busybox', 'ls', host_config=self.client.create_host_config(
+                cgroup='host'
+            )
+        )
+
+        args = fake_request.call_args
+        assert args[0][1] == url_prefix + 'containers/create'
+        data = json.loads(args[1]['data'])
+        assert 'HostConfig' in data
+        assert 'Cgroup' in data['HostConfig']
+        assert data['HostConfig']['Cgroup'] == 'host'
+
     def test_create_container_with_working_dir(self):
         self.client.create_container('busybox', 'ls',
                                      working_dir='/root')

tests/unit/models_containers_test.py

@@ -49,6 +49,7 @@ def test_create_container_args(self):
             'cap_add': ['foo'],
             'cap_drop': ['bar'],
             'cgroup_parent': 'foobar',
+            'cgroup': 'host',
             'cgroupns': 'host',
             'cpu_period': 1,
             'cpu_quota': 2,