Add support to regenerate port mac_address

Passing 'null' (None) as the mac address in a port update
request causes the port's mac address to be re-generated
using the base MAC address Neutron uses for VIFs.

This change implementes a temporary lib api definition
with a new converter that will generate valid mac if the
data provided is None.

APIImpact: Port mac_addr regenerated if None passed on update.
Closes-Bug: #1768690
Change-Id: I7d04beea4810718c3b745de8ea97897b1323267e

neutron/extensions/_port_mac_address_regenerate_lib.py

@@ -0,0 +1,59 @@
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+
+"""
+TODO(hjensas): This module should be deleted once neutron-lib containing
+Change-Id: Ibfcf179c2051d2bf47d4d1e62e8146cbee29fd64 is released.
+"""
+
+from neutron_lib.api.definitions import port as port_def
+from neutron_lib import constants
+from neutron_lib.utils import net as net_utils
+from oslo_config import cfg
+
+
+def convert_to_mac_if_none(data):
+    """Convert to a random mac address if data is None
+
+    :param data: The data value
+    :return: Random mac address if data is None, else return data.
+    """
+    if data is None:
+        return net_utils.get_random_mac(cfg.CONF.base_mac.split(':'))
+
+    return data
+
+
+NAME = 'Neutron Port MAC address regenerate'
+ALIAS = 'port-mac-address-regenerate'
+DESCRIPTION = "Network port MAC address regenerate"
+UPDATED_TIMESTAMP = "2018-05-03T10:00:00-00:00"
+
+RESOURCE_ATTRIBUTE_MAP = {
+    port_def.COLLECTION_NAME: {
+        'mac_address': {'allow_post': True, 'allow_put': True,
+                        'default': constants.ATTR_NOT_SPECIFIED,
+                        'convert_to': convert_to_mac_if_none,
+                        'validate': {'type:mac_address': None},
+                        'enforce_policy': True,
+                        'is_visible': True},
+    }
+}
+
+IS_SHIM_EXTENSION = False
+IS_STANDARD_ATTR_EXTENSION = False
+SUB_RESOURCE_ATTRIBUTE_MAP = {}
+ACTION_MAP = {}
+REQUIRED_EXTENSIONS = []
+OPTIONAL_EXTENSIONS = []
+ACTION_STATUS = {}

neutron/extensions/port_mac_address_regenerate.py

@@ -0,0 +1,24 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# TODO(hjensas) When we have neutron-lib release, use it.
+# from neutron_lib.api.definitions import port_mac_address_regenerate as apidef
+
+from neutron.extensions import _port_mac_address_regenerate_lib as apidef
+from neutron_lib.api import extensions as api_extensions
+
+
+class Port_mac_address_regenerate(api_extensions.APIExtensionDescriptor):
+    """Extension to support port MAC address regeneration"""
+
+    api_definition = apidef

neutron/plugins/ml2/plugin.py

@@ -159,7 +159,8 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                                     "subnet-service-types",
                                     "ip-substring-filtering",
                                     "port-security-groups-filtering",
-                                    "empty-string-filtering"]
+                                    "empty-string-filtering",
+                                    "port-mac-address-regenerate"]
 
     @property
     def supported_extension_aliases(self):

neutron/tests/contrib/hooks/api_all_extensions

@@ -40,6 +40,7 @@ NETWORK_API_EXTENSIONS+=",rbac-policies"
 NETWORK_API_EXTENSIONS+=",router"
 NETWORK_API_EXTENSIONS+=",router_availability_zone"
 NETWORK_API_EXTENSIONS+=",security-group"
+NETWORK_API_EXTENSIONS+=",port-mac-address-regenerate"
 NETWORK_API_EXTENSIONS+=",port-security-groups-filtering"
 NETWORK_API_EXTENSIONS+=",segment"
 NETWORK_API_EXTENSIONS+=",service-type"

neutron/tests/unit/plugins/ml2/test_plugin.py

@@ -962,6 +962,29 @@ class TestMl2PortsV2(test_plugin.TestPortsV2, Ml2PluginV2TestCase):
             host_arg={portbindings.HOST_ID: HOST},
             arg_list=(portbindings.HOST_ID,))
 
+    def test_update_port_regenerate_mac(self):
+        ctx = context.get_admin_context()
+        plugin = directory.get_plugin()
+        data = {'port': {'mac_address': None}}
+        with self.port() as port:
+            current_mac = port['port']['mac_address']
+            req = self.new_update_request('ports', data, port['port']['id'])
+            self.assertEqual(200, req.get_response(self.api).status_int)
+            new_mac = plugin.get_port(ctx, port['port']['id'])['mac_address']
+            self.assertNotEqual(current_mac, new_mac)
+            self.assertTrue(netaddr.valid_mac(new_mac))
+
+    def test_update_port_mac_does_not_change(self):
+        ctx = context.get_admin_context()
+        plugin = directory.get_plugin()
+        data = {'port': {'description': 'Port Description'}}
+        with self.port() as port:
+            current_mac = port['port']['mac_address']
+            req = self.new_update_request('ports', data, port['port']['id'])
+            self.assertEqual(200, req.get_response(self.api).status_int)
+            new_mac = plugin.get_port(ctx, port['port']['id'])['mac_address']
+            self.assertEqual(current_mac, new_mac)
+
     def test_update_non_existent_port(self):
         ctx = context.get_admin_context()
         plugin = directory.get_plugin()

releasenotes/notes/port-mac-address-regenerate-312978c834abaa52.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    Adds  api extenstion ``port-mac-address-regenerate``. When passing
+    ``'null'`` (``None``) as the ``mac_address`` on port update a converter
+    will generate a new mac address that will be assigned to the port.
+    `RFE:  #1768690 <https://bugs.launchpad.net/neutron/+bug/1768690>`_.