Add check on docker_volume_size

In magnum server side, docker_volume_size allowed minimum value is 1GB.
In fact, the minimum value should be 3GB when docker-storage-driver is
devicemapper, because the limitation of docker-storage-setup. So, I add
check on "--docker-volume-size". If "--docker-storage-driver=devicemapper",
the minimum docker-volume-size should be 3GB, otherwise it should 1GB.

Change-Id: I53c6a9c93ee156fa9afabdbd72a87bb4044d71ca
Closes-Bug: #1583878

doc/source/dev/tls.rst

@@ -47,7 +47,7 @@ Create a baymodel, by default TLS is enabled in Magnum::
                            --external-network-id public \
                            --image-id fedora-atomic-latest \
                            --flavor-id m1.small \
-                           --docker-volume-size 1 \
+                           --docker-volume-size 3 \
                            --coe kubernetes \
                            --network-driver flannel
 
@@ -65,7 +65,7 @@ Create a baymodel, by default TLS is enabled in Magnum::
     | keypair_id          | default                              |
     | public              | False                                |
     | labels              | {}                                   |
-    | docker_volume_size  | 1                                    |
+    | docker_volume_size  | 3                                    |
     | external_network_id | public                               |
     | cluster_distro      | fedora-atomic                        |
     | image_id            | fedora-atomic-latest                 |

doc/source/userguide.rst

@@ -200,7 +200,9 @@ They are loosely grouped as: mandatory, infrastructure, COE specific.
 --docker-volume-size \<docker-volume-size\>
   The size in GB for the local storage on each server for the Docker
   daemon to cache the images and host the containers.  Cinder volumes
-  provide the storage.  The default is 25 GB.
+  provide the storage.  The default is 25 GB. For the 'devicemapper'
+  storage driver, the minimum value is 3GB. For the 'overlay' storage
+  driver, the minimum value is 1GB.
 
 --docker-storage-driver \<docker-storage-driver\>
   The name of a driver to manage the storage for the images and the

magnum/api/controllers/v1/baymodel.py

@@ -318,6 +318,7 @@ class BayModelsController(rest.RestController):
     @expose.expose(BayModel, body=BayModel, status_code=201)
     @validation.enforce_network_driver_types_create()
     @validation.enforce_volume_driver_types_create()
+    @validation.enforce_volume_storage_size_create()
     def post(self, baymodel):
         """Create a new baymodel.
 

magnum/api/validation.py

@@ -133,6 +133,16 @@ def enforce_volume_driver_types_create():
     return wrapper
 
 
+def enforce_volume_storage_size_create():
+    @decorator.decorator
+    def wrapper(func, *args, **kwargs):
+        baymodel = args[1]
+        _enforce_volume_storage_size(baymodel.as_dict())
+        return func(*args, **kwargs)
+
+    return wrapper
+
+
 def enforce_volume_driver_types_update():
     @decorator.decorator
     def wrapper(func, *args, **kwargs):
@@ -157,6 +167,19 @@ def _enforce_volume_driver_types(baymodel):
     validator.validate_volume_driver(baymodel['volume_driver'])
 
 
+def _enforce_volume_storage_size(baymodel):
+    if not baymodel.get('docker_volume_size'):
+        return
+    volume_size = baymodel.get('docker_volume_size')
+    storage_driver = baymodel.get('docker_storage_driver')
+    if storage_driver == 'devicemapper':
+        if volume_size < 3:
+            raise exception.InvalidParameterValue(
+                'docker volume size %s GB is not valid, '
+                'expecting minimum value 3GB for %s storage '
+                'driver.') % (volume_size, storage_driver)
+
+
 def validate_bay_properties(delta):
 
     update_disallowed_properties = delta - bay_update_allowed_properties

magnum/tests/unit/api/controllers/v1/test_baymodel.py

@@ -541,6 +541,12 @@ class TestPost(api_base.FunctionalTest):
     def test_create_baymodel_with_invalid_docker_volume_size(self):
         self._create_baymodel_raises_app_error(docker_volume_size=0)
         self._create_baymodel_raises_app_error(docker_volume_size=-1)
+        self._create_baymodel_raises_app_error(
+            docker_volume_size=1,
+            docker_storage_driver="devicemapper")
+        self._create_baymodel_raises_app_error(
+            docker_volume_size=2,
+            docker_storage_driver="devicemapper")
         self._create_baymodel_raises_app_error(docker_volume_size='notanint')
 
     def test_create_baymodel_with_invalid_dns_nameserver(self):
@@ -583,6 +589,20 @@ class TestPost(api_base.FunctionalTest):
             cc_mock.assert_called_once_with(mock.ANY)
             self.assertNotIn('id', cc_mock.call_args[0][0])
 
+    @mock.patch('magnum.api.attr_validator.validate_image')
+    def test_create_baymodel_with_overlay(self, mock_image_data):
+        with mock.patch.object(self.dbapi, 'create_baymodel',
+                               wraps=self.dbapi.create_baymodel) as cc_mock:
+            mock_image_data.return_value = {'name': 'mock_name',
+                                            'os_distro': 'fedora-atomic'}
+            bdict = apiutils.baymodel_post_data(
+                docker_volume_size=1, docker_storage_driver="overlay")
+            response = self.post_json('/baymodels', bdict)
+            self.assertEqual(bdict['docker_volume_size'],
+                             response.json['docker_volume_size'])
+            cc_mock.assert_called_once_with(mock.ANY)
+            self.assertNotIn('id', cc_mock.call_args[0][0])
+
     @mock.patch('magnum.api.attr_validator.validate_image')
     def test_create_baymodel_generate_uuid(self,
                                            mock_image_data):