Add `CapabilityAdd` and `CapabilityDrop` to

ContainerSpec

Docker Engine v1.41 added `CapAdd` and `CapDrop` as part of the
ContainerSpec, and `docker-py` should do the same.

```
GET /services now returns CapAdd and CapDrop as part of the ContainerSpec.
GET /services/{id} now returns CapAdd and CapDrop as part of the ContainerSpec.
POST /services/create now accepts CapAdd and CapDrop as part of the ContainerSpec.
POST /services/{id}/update now accepts CapAdd and CapDrop as part of the ContainerSpec.
GET /tasks now returns CapAdd and CapDrop as part of the ContainerSpec.
GET /tasks/{id} now returns CapAdd and CapDrop as part of the ContainerSpec.
```

I added capabilities on docstrings, `service.create` init method and
create tests for that.

That change was mention in issue #2802.

Signed-off-by: Felipe Ruhland <felipe.ruhland@gmail.com>

docker/models/services.py

@@ -213,6 +213,10 @@ class ServiceCollection(Collection):
                 to the service.
             privileges (Privileges): Security options for the service's
                 containers.
+            cap_add (:py:class:`list`): A list of kernel capabilities to add to
+                the default set for the container.
+            cap_drop (:py:class:`list`): A list of kernel capabilities to drop
+                from the default set for the container.
 
         Returns:
             :py:class:`Service`: The created service.
@@ -277,6 +281,8 @@ class ServiceCollection(Collection):
 # kwargs to copy straight over to ContainerSpec
 CONTAINER_SPEC_KWARGS = [
     'args',
+    'cap_add',
+    'cap_drop',
     'command',
     'configs',
     'dns_config',

docker/types/services.py

@@ -112,13 +112,18 @@ class ContainerSpec(dict):
             containers. Only used for Windows containers.
         init (boolean): Run an init inside the container that forwards signals
             and reaps processes.
+        cap_add (:py:class:`list`): A list of kernel capabilities to add to the
+            default set for the container.
+        cap_drop (:py:class:`list`): A list of kernel capabilities to drop from
+            the default set for the container.
     """
     def __init__(self, image, command=None, args=None, hostname=None, env=None,
                  workdir=None, user=None, labels=None, mounts=None,
                  stop_grace_period=None, secrets=None, tty=None, groups=None,
                  open_stdin=None, read_only=None, stop_signal=None,
                  healthcheck=None, hosts=None, dns_config=None, configs=None,
-                 privileges=None, isolation=None, init=None):
+                 privileges=None, isolation=None, init=None, cap_add=None,
+                 cap_drop=None):
         self['Image'] = image
 
         if isinstance(command, six.string_types):
@@ -188,6 +193,18 @@ class ContainerSpec(dict):
         if init is not None:
             self['Init'] = init
 
+        if cap_add is not None:
+            if not isinstance(cap_add, list):
+                raise TypeError('cap_add must be a list')
+
+            self['CapabilityAdd'] = cap_add
+
+        if cap_drop is not None:
+            if not isinstance(cap_drop, list):
+                raise TypeError('cap_drop must be a list')
+
+            self['CapabilityDrop'] = cap_drop
+
 
 class Mount(dict):
     """

tests/integration/api_service_test.py

@@ -1358,3 +1358,33 @@ class ServiceTest(BaseAPIIntegrationTest):
                 self.client.update_service(*args, **kwargs)
             else:
                 raise
+
+    @requires_api_version('1.41')
+    def test_create_service_cap_add(self):
+        name = self.get_service_name()
+        container_spec = docker.types.ContainerSpec(
+            TEST_IMG, ['echo', 'hello'], cap_add=['CAP_SYSLOG']
+        )
+        task_tmpl = docker.types.TaskTemplate(container_spec)
+        svc_id = self.client.create_service(task_tmpl, name=name)
+        assert self.client.inspect_service(svc_id)
+        services = self.client.services(filters={'name': name})
+        assert len(services) == 1
+        assert services[0]['ID'] == svc_id['ID']
+        spec = services[0]['Spec']['TaskTemplate']['ContainerSpec']
+        assert 'CAP_SYSLOG' in spec['CapabilityAdd']
+
+    @requires_api_version('1.41')
+    def test_create_service_cap_drop(self):
+        name = self.get_service_name()
+        container_spec = docker.types.ContainerSpec(
+            TEST_IMG, ['echo', 'hello'], cap_drop=['CAP_SYSLOG']
+        )
+        task_tmpl = docker.types.TaskTemplate(container_spec)
+        svc_id = self.client.create_service(task_tmpl, name=name)
+        assert self.client.inspect_service(svc_id)
+        services = self.client.services(filters={'name': name})
+        assert len(services) == 1
+        assert services[0]['ID'] == svc_id['ID']
+        spec = services[0]['Spec']['TaskTemplate']['ContainerSpec']
+        assert 'CAP_SYSLOG' in spec['CapabilityDrop']

tests/integration/models_services_test.py

@@ -333,3 +333,41 @@ class ServiceTest(unittest.TestCase):
         assert service.force_update()
         service.reload()
         assert service.version > initial_version
+
+    @helpers.requires_api_version('1.41')
+    def test_create_cap_add(self):
+        client = docker.from_env(version=TEST_API_VERSION)
+        name = helpers.random_name()
+        service = client.services.create(
+            name=name,
+            labels={'foo': 'bar'},
+            image="alpine",
+            command="sleep 300",
+            container_labels={'container': 'label'},
+            cap_add=["CAP_SYSLOG"]
+        )
+        assert service.name == name
+        assert service.attrs['Spec']['Labels']['foo'] == 'bar'
+        container_spec = service.attrs['Spec']['TaskTemplate']['ContainerSpec']
+        assert "alpine" in container_spec['Image']
+        assert container_spec['Labels'] == {'container': 'label'}
+        assert "CAP_SYSLOG" in container_spec["CapabilityAdd"]
+
+    @helpers.requires_api_version('1.41')
+    def test_create_cap_drop(self):
+        client = docker.from_env(version=TEST_API_VERSION)
+        name = helpers.random_name()
+        service = client.services.create(
+            name=name,
+            labels={'foo': 'bar'},
+            image="alpine",
+            command="sleep 300",
+            container_labels={'container': 'label'},
+            cap_drop=["CAP_SYSLOG"]
+        )
+        assert service.name == name
+        assert service.attrs['Spec']['Labels']['foo'] == 'bar'
+        container_spec = service.attrs['Spec']['TaskTemplate']['ContainerSpec']
+        assert "alpine" in container_spec['Image']
+        assert container_spec['Labels'] == {'container': 'label'}
+        assert "CAP_SYSLOG" in container_spec["CapabilityDrop"]