Add ``neutron-load-balancer`` interface

Send name and URL down the relation to make ``neutron-api``
configure and point the ``lbaasv2-proxy`` service at us.

Change-Id: Ib013afdd7a0b635ab65de8d1cd2f5e83512a6a2a

src/layer.yaml

@@ -4,6 +4,7 @@ includes:
   - interface:mysql-shared
   - interface:rabbitmq
   - interface:keystone
+  - interface:neutron-load-balancer
 options:
   basic:
     use_venv: True

src/metadata.yaml

@@ -19,3 +19,6 @@ tags:
 series:
   - bionic
 subordinate: false
+requires:
+  neutron-load-balancer:
+    interface: neutron-load-balancer

src/reactive/octavia_handlers.py

@@ -18,6 +18,7 @@ import charms.reactive as reactive
 import charms.leadership as leadership
 
 import charms_openstack.charm as charm
+import charms_openstack.ip as os_ip
 
 import charm.openstack.octavia as octavia  # noqa
 
@@ -38,6 +39,16 @@ def generate_heartbeat_key():
     leadership.leader_set({'heartbeat-key': str(uuid.uuid4())})
 
 
+@reactive.when('neutron-load-balancer.available')
+def setup_neutron_lbaas_proxy():
+    neutron = reactive.endpoint_from_flag('neutron-load-balancer.available')
+    with charm.provide_charm_instance() as octavia_charm:
+        octavia_url = '{}:{}'.format(
+            os_ip.canonical_url(endpoint_type=os_ip.INTERNAL),
+            octavia_charm.api_port('octavia-api'))
+        neutron.publish_load_balancer_info('octavia', octavia_url)
+
+
 @reactive.when('shared-db.available')
 @reactive.when('identity-service.available')
 @reactive.when('amqp.available')

unit_tests/test_octavia_handlers.py

@@ -42,6 +42,8 @@ class TestRegisteredHooks(test_utils.TestRegisteredHooks):
                 'init_db': ('config.rendered',),
                 'cluster_connected': ('ha.connected',),
                 'generate_heartbeat_key': ('leadership.is_leader',),
+                'setup_neutron_lbaas_proxy': (
+                    'neutron-load-balancer.available',),
             },
             'when_not': {
                 'init_db': ('db.synced',),
@@ -74,6 +76,24 @@ class TestOctaviaHandlers(test_utils.PatchHelper):
             {'heartbeat-key': fake_uuid4})
         self.uuid4.assert_called_once_with()
 
+    def test_neutron_lbaas_proxy(self):
+        octavia_charm = mock.MagicMock()
+        self.patch_object(handlers.charm, 'provide_charm_instance',
+                          new=mock.MagicMock())
+        self.provide_charm_instance().__enter__.return_value = octavia_charm
+        self.provide_charm_instance().__exit__.return_value = None
+
+        self.patch('charms.reactive.endpoint_from_flag', 'endpoint_from_flag')
+        endpoint = mock.MagicMock()
+        self.endpoint_from_flag.return_value = endpoint
+        self.patch('charms_openstack.ip.canonical_url', 'canonical_url')
+        self.canonical_url.return_value = 'http://1.2.3.4'
+        octavia_charm.api_port.return_value = '1234'
+        handlers.setup_neutron_lbaas_proxy()
+        self.canonical_url.assert_called_with(endpoint_type='int')
+        endpoint.publish_load_balancer_info.assert_called_with(
+            'octavia', 'http://1.2.3.4:1234')
+
     def test_render(self):
         self.patch('charms.reactive.set_state', 'set_state')
         handlers.render('arg1', 'arg2')