Rehome net-mtu-enh extension definition

This new extension allows to set mtu on create and update. Plugins are
free to implement only create if needed, returning a meaningful error if
update is not supported. Plugins should also make sure that MTU makes
general sense in context of corresponding deployment.

Plugins supporting the new extension are expected to signal support for
net-mtu too because the new extension is a superset of the old feature.

We can't just update the existing net-mtu extension because then support
for writes is not discoverable.

Change-Id: I3dd29578cee4ac4f9f55f6500965664e9e8069a6
Related-Bug: #1671634

neutron_lib/api/definitions/__init__.py

@@ -36,6 +36,7 @@ from neutron_lib.api.definitions import network
 from neutron_lib.api.definitions import network_availability_zone
 from neutron_lib.api.definitions import network_ip_availability
 from neutron_lib.api.definitions import network_mtu
+from neutron_lib.api.definitions import network_mtu_writable
 from neutron_lib.api.definitions import pagination
 from neutron_lib.api.definitions import port
 from neutron_lib.api.definitions import port_security
@@ -80,6 +81,7 @@ _ALL_API_DEFINITIONS = {
     network_availability_zone,
     network_ip_availability,
     network_mtu,
+    network_mtu_writable,
     pagination,
     port,
     port_security,

neutron_lib/api/definitions/network_mtu_writable.py

@@ -0,0 +1,82 @@
+# All rights reserved.
+#
+#    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.
+
+from neutron_lib.api import converters
+from neutron_lib.api.definitions import network
+from neutron_lib.api.definitions import network_mtu
+
+
+MTU = 'mtu'
+
+# The alias of the extension.
+ALIAS = 'net-mtu-writable'
+
+# The label to lookup the plugin in the plugin directory. It can match the
+# alias, as required.
+LABEL = ALIAS
+
+# Whether or not this extension is simply signaling behavior to the user
+# or it actively modifies the attribute map.
+IS_SHIM_EXTENSION = False
+
+# Whether the extension is marking the adoption of standardattr model for
+# legacy resources, or introducing new standardattr attributes. False or
+# None if the standardattr model is adopted since the introduction of
+# resource extension.
+# If this is True, the alias for the extension should be prefixed with
+# 'standard-attr-'.
+IS_STANDARD_ATTR_EXTENSION = False
+
+# The name of the extension.
+NAME = 'Network MTU (writable)'
+
+# A prefix for API resources. An empty prefix means that the API is going
+# to be exposed at the v2/ level as any other core resource.
+API_PREFIX = ''
+
+# The description of the extension.
+DESCRIPTION = (
+    "Provides a writable MTU attribute for a network resource.")
+
+# A timestamp of when the extension was introduced.
+UPDATED_TIMESTAMP = "2017-07-12T00:00:00-00:00"
+
+
+RESOURCE_ATTRIBUTE_MAP = {
+    network.COLLECTION_NAME: {
+        MTU: {'allow_post': True, 'allow_put': True, 'is_visible': True,
+              'validate': {'type:non_negative': None}, 'default': 0,
+              'convert_to': converters.convert_to_int},
+    },
+}
+
+# The subresource attribute map for the extension. It adds child resources
+# to main extension's resource. The subresource map must have a parent and
+# a parameters entry. If an extension does not need such a map, None can
+# be specified (mandatory).
+SUB_RESOURCE_ATTRIBUTE_MAP = {}
+
+# The action map: it associates verbs with methods to be performed on
+# the API resource.
+ACTION_MAP = {}
+
+# The action status.
+ACTION_STATUS = {
+}
+
+# The list of required extensions.
+REQUIRED_EXTENSIONS = [network_mtu.ALIAS]
+
+# The list of optional extensions.
+OPTIONAL_EXTENSIONS = []

neutron_lib/tests/unit/api/definitions/test_network_mtu_writable.py

@@ -0,0 +1,19 @@
+#    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.
+
+from neutron_lib.api.definitions import network_mtu_writable
+from neutron_lib.tests.unit.api.definitions import base
+
+
+class NetworkMtuDefinitionTestCase(base.DefinitionBaseTestCase):
+    extension_module = network_mtu_writable
+    extension_attributes = ('mtu',)

releasenotes/notes/create-netmtu-writable-extension-284892119ef6595c.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - The new ``net-mtu-writable`` extension API definition has been added as
+    ``neutron_lib.api.definitions.network_mtu_writable``. The new extension
+    indicates that the network ``mtu`` attribute is writeable.  Plugins
+    supporting the new extension are expected to also support ``net-mtu``.