Merge pull request #73 from Aflynn50/add-dbcluster-relation-departed

Remove unit addresses on dbcluster relation departed

src/charm.py

@@ -62,6 +62,8 @@ def _observe(self):
             self.on.metrics_endpoint_relation_broken, self._on_metrics_endpoint_relation_broken)
         self.framework.observe(
             self.on.dbcluster_relation_changed, self._on_dbcluster_relation_changed)
+        self.framework.observe(
+            self.on.dbcluster_relation_departed, self._on_dbcluster_relation_departed)
 
     def _on_install(self, event: InstallEvent):
         """Ensure that the controller configuration file exists."""
@@ -157,12 +159,20 @@ def _on_metrics_endpoint_relation_broken(self, event: RelationDepartedEvent):
         self._control_socket.remove_metrics_user(username)
 
     def _on_dbcluster_relation_changed(self, event):
+        relation = event.relation
+        self._update_bind_addresses(relation)
+
+    def _on_dbcluster_relation_departed(self, event):
+        relation = event.relation
+        self._update_bind_addresses(relation)
+
+    def _update_bind_addresses(self, relation):
         """Maintain our own bind address in relation data.
         If we are the leader, aggregate the bind addresses for all the peers,
         and ensure the result is set in the application data bag.
         If the aggregate addresses have changed, rewrite the config file.
         """
-        relation = event.relation
+
         try:
             ip = self._set_db_bind_address(relation)
         except DBBindAddressException as e:

tests/test_charm.py

@@ -158,7 +158,7 @@ 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.
+        # This unit's agent ID happens to correspond with the unit ID.
         mock_get_agent_id.return_value = '0'
 
         harness.set_leader()
@@ -247,6 +247,45 @@ def test_dbcluster_relation_changed_write_file(
         # The last thing we should have done is send a reload request via the socket..
         mock_reload_config.assert_called_once()
 
+    @patch("builtins.open", new_callable=mock_open, read_data=agent_conf)
+    @patch("configchangesocket.ConfigChangeSocketClient.get_controller_agent_id")
+    @patch("ops.model.Model.get_binding")
+    @patch("configchangesocket.ConfigChangeSocketClient.reload_config")
+    def test_dbcluster_relation_departed(
+            self, mock_reload_config, mock_get_binding, mock_get_agent_id, *__):
+        harness = self.harness
+        mock_get_binding.return_value = mockBinding(['192.168.1.17'])
+
+        # This unit's agent ID happens to correspond with the unit ID.
+        mock_get_agent_id.return_value = '0'
+
+        harness.set_leader()
+
+        # Have another unit enter the relation.
+        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',
+                'agent-id': '9',
+            })
+
+        # Assert that the second units agent bind address is in the data bag.
+        app_data = harness.get_relation_data(relation_id, 'juju-controller')
+        exp = {'0': '192.168.1.17', '9': '192.168.1.100'}
+        self.assertEqual(json.loads(app_data['db-bind-addresses']), exp)
+
+        # Remove the second unit.
+        harness.remove_relation_unit(relation_id, 'juju-controller/1')
+
+        # Assert that the second unit's address is gone from the data bag.
+        app_data = harness.get_relation_data(relation_id, 'juju-controller')
+        exp = {'0': '192.168.1.17'}
+        self.assertEqual(json.loads(app_data['db-bind-addresses']), exp)
+
+        harness.evaluate_status()
+        self.assertIsInstance(harness.charm.unit.status, ActiveStatus)
+
 
 class mockNetwork:
     def __init__(self, addresses):