Merge pull request #70 from juju/set-agent-id

Use the agent ID instead of unit ID in cluster config dict

src/charm.py

@@ -27,6 +27,7 @@ class JujuControllerCharm(CharmBase):
     CONFIG_SOCKET_PATH = '/var/lib/juju/configchange.socket'
     DB_BIND_ADDR_KEY = 'db-bind-address'
     ALL_BIND_ADDRS_KEY = 'db-bind-addresses'
+    AGENT_ID_KEY = 'agent-id'
 
     _stored = StoredState()
 
@@ -170,12 +171,13 @@ def _on_dbcluster_relation_changed(self, event):
             # The event only has *other* units so include this
             # unit's bind address if we have managed to set it.
             ip = self._stored.db_bind_address
-            all_bind_addresses = {self.unit.name: ip} if ip else dict()
+            all_bind_addresses = {self._controller_agent_id(): ip} if ip else dict()
 
             for unit in relation.units:
                 unit_data = relation.data[unit]
                 if self.DB_BIND_ADDR_KEY in unit_data:
-                    all_bind_addresses[unit.name] = unit_data[self.DB_BIND_ADDR_KEY]
+                    agent_id = unit_data[self.AGENT_ID_KEY]
+                    all_bind_addresses[agent_id] = unit_data[self.DB_BIND_ADDR_KEY]
 
             if self._stored.all_bind_addresses == all_bind_addresses:
                 return
@@ -211,7 +213,10 @@ def _ensure_db_bind_address(self, relation):
             return
 
         logger.info('setting new DB bind address: %s', ip)
-        relation.data[self.unit].update({self.DB_BIND_ADDR_KEY: ip})
+        relation.data[self.unit].update({
+            self.DB_BIND_ADDR_KEY: ip,
+            self.AGENT_ID_KEY: self._controller_agent_id()
+        })
         self._stored.db_bind_address = ip
 
     def _update_config_file(self, bind_addresses):
@@ -261,11 +266,14 @@ def _controller_config_path(self) -> str:
         """Interrogate the running controller jujud service to determine
         the local controller ID, then use it to construct a config path.
         """
-        controller_id = self._config_change_socket.get_controller_agent_id()
+        controller_id = self._controller_agent_id()
         return f'/var/lib/juju/agents/controller-{controller_id}/controller.conf'
 
+    def _controller_agent_id(self):
+        return self._config_change_socket.get_controller_agent_id()
+
     def _request_config_reload(self):
-        """Send a reload request to the config reload socket"""
+        """Send a reload request to the config reload socket."""
         self._config_change_socket.reload_config()
 
 

tests/test_charm.py

@@ -158,24 +158,30 @@ def test_dbcluster_relation_changed_single_addr(
         harness = self.harness
         mock_get_binding.return_value = mockBinding(['192.168.1.17'])
 
+        # This unit's agent ID happends to correspond with the unit ID.
         mock_get_agent_id.return_value = '0'
 
         harness.set_leader()
 
         # Have another unit enter the relation.
         # Its bind address should end up in the application data bindings list.
+        # Note that the agent ID doesn not correspond with the unit's ID
         relation_id = harness.add_relation('dbcluster', harness.charm.app)
         harness.add_relation_unit(relation_id, 'juju-controller/1')
         self.harness.update_relation_data(
-            relation_id, 'juju-controller/1', {'db-bind-address': '192.168.1.100'})
+            relation_id, 'juju-controller/1', {
+                'db-bind-address': '192.168.1.100',
+                'agent-id': '9',
+            })
 
         mock_reload_config.assert_called_once()
 
         unit_data = harness.get_relation_data(relation_id, 'juju-controller/0')
         self.assertEqual(unit_data['db-bind-address'], '192.168.1.17')
+        self.assertEqual(unit_data['agent-id'], '0')
 
         app_data = harness.get_relation_data(relation_id, 'juju-controller')
-        exp = {"juju-controller/0": "192.168.1.17", "juju-controller/1": "192.168.1.100"}
+        exp = {'0': '192.168.1.17', '9': '192.168.1.100'}
         self.assertEqual(json.loads(app_data['db-bind-addresses']), exp)
 
         harness.evaluate_status()