initial L3 understack plugin setup

components/neutron/aio-values.yaml

@@ -52,7 +52,7 @@ conf:
         type_drivers: "vlan,local,understack_vxlan"
   neutron:
     DEFAULT:
-      service_plugins: "router,segments,port_forwarding"
+      service_plugins: "l3_understack,router,segments,port_forwarding"
       # we don't want HA L3 routers. It's a Python value so we need to quote it in YAML.
       l3_ha: "False"
       # we aren't using availability zones so having calls attempt to add things to

python/neutron-understack/neutron_understack/l3_service_plugin.py

@@ -0,0 +1,20 @@
+from neutron_lib.services.base import ServicePluginBase
+from neutron.db.l3_db import L3_NAT_db_mixin
+from neutron_understack_mech import log_call
+
+
+class UnderStackL3ServicePlugin(ServicePluginBase, L3_NAT_db_mixin):
+    def __init__(self):
+        super().__init__()
+
+    def get_plugin_type(self):
+        return "L3_ROUTER_NAT"
+
+    def get_plugin_description(self):
+        return "Understack L3 Service Plugin"
+
+    def create_router(self, context, router):
+        log_call("create_router", context)
+        router_dict = super().create_router(context,
+                                            router)
+        return router_dict