Shim extension - segments peer subnet host routes, and api-ref

Adds shim extension for segment peer-subnet host routes.
Adds api-ref documentation of the new extension.

Related-Bug: 1766380
Depends-On: Iafbabe6352283e7f1a535a7b147bd81fb32f0ed1
Change-Id: Ibd1b565a04a6d979b6e56ca5469af644894d6b4c

api-ref/source/v2/subnets.inc

@@ -47,6 +47,17 @@ The subnet segment_id writable (``subnet-segmentid-writable``) extension
 enhances the `Segments`_ (``segment``) extension in that now the ``segment_id``
 attribute is also available for write when a subnet is updated.
 
+Segment peer subnet host routes extension
+=========================================
+
+The segment peer subnet host routes extension (
+``segments-peer-subnet-host-routes``) extension enhances the `Segments`_
+(``segment``) extension in that now the ``host_routes`` property of the
+different `Subnets`_ (``subnets``) in a routed network gets routes to the peer
+subnets on different segments added automatically. This ensures that traffic
+within an L3 routed network stays within the network even when the default
+route is on a different host interface.
+
 Subnet service types extension
 ==============================
 

neutron_lib/api/definitions/__init__.py

@@ -74,6 +74,7 @@ from neutron_lib.api.definitions import router_interface_fip
 from neutron_lib.api.definitions import routerservicetype
 from neutron_lib.api.definitions import security_groups_port_filtering
 from neutron_lib.api.definitions import segment
+from neutron_lib.api.definitions import segments_peer_subnet_host_routes
 from neutron_lib.api.definitions import servicetype
 from neutron_lib.api.definitions import sfc
 from neutron_lib.api.definitions import sorting
@@ -156,6 +157,7 @@ _ALL_API_DEFINITIONS = {
     routerservicetype,
     security_groups_port_filtering,
     segment,
+    segments_peer_subnet_host_routes,
     servicetype,
     sfc,
     sorting,

neutron_lib/api/definitions/segments_peer_subnet_host_routes.py

@@ -0,0 +1,27 @@
+#    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 segment
+
+
+ALIAS = 'segments-peer-subnet-host-routes'
+IS_SHIM_EXTENSION = True
+IS_STANDARD_ATTR_EXTENSION = False
+NAME = 'Segments peer-subnet host routes'
+DESCRIPTION = 'Add host routes to subnets on a routed network (segments)'
+UPDATED_TIMESTAMP = '2018-06-12T10:00:00-00:00'
+RESOURCE_ATTRIBUTE_MAP = {}
+SUB_RESOURCE_ATTRIBUTE_MAP = {}
+ACTION_MAP = {}
+REQUIRED_EXTENSIONS = [segment.ALIAS]
+OPTIONAL_EXTENSIONS = []
+ACTION_STATUS = {}

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

@@ -0,0 +1,18 @@
+#    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 segments_peer_subnet_host_routes
+from neutron_lib.tests.unit.api.definitions import base
+
+
+class SegmentPeerHostRoutesDefinitionTestCase(base.DefinitionBaseTestCase):
+    extension_module = segments_peer_subnet_host_routes

releasenotes/notes/routed-networks-hostroutes-fb43abf942b154ff.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Adds api-extension ``segments-peer-subnet-host-routes``. Adds host routes
+    to subnets on a routed network (segments). `RFE: 1766380
+    <https://bugs.launchpad.net/neutron/+bug/1766380>`_.