DPE-4699 Set instance offline mode on restore (#478)

* ensure username uniqueness

* libs bump

* temporary branch for router

* test against temp branch revision of router

* support for legacy username format

* model uuid as suffix

* put instance in offline mode

* bump lib

* leftover

lib/charms/data_platform_libs/v0/upgrade.py

@@ -285,7 +285,7 @@ def restart(self, event) -> None:
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 17
+LIBPATCH = 18
 
 PYDEPS = ["pydantic>=1.10,<2", "poetry-core"]
 
@@ -921,7 +921,7 @@ def _on_upgrade_charm(self, event: UpgradeCharmEvent) -> None:
             self.charm.unit.status = WaitingStatus("other units upgrading first...")
             self.peer_relation.data[self.charm.unit].update({"state": "ready"})
 
-            if self.charm.app.planned_units() == 1:
+            if len(self.app_units) == 1:
                 # single unit upgrade, emit upgrade_granted event right away
                 getattr(self.on, "upgrade_granted").emit()
 

lib/charms/mysql/v0/backups.py

@@ -99,7 +99,7 @@ def is_unit_blocked(self) -> bool:
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 9
+LIBPATCH = 10
 
 
 if typing.TYPE_CHECKING:
@@ -557,9 +557,12 @@ def _pre_restore(self) -> Tuple[bool, str]:
         try:
             logger.info("Stopping mysqld before restoring the backup")
             self.charm._mysql.kill_client_sessions()
+            self.charm._mysql.set_instance_offline_mode(True)
             self.charm._mysql.stop_mysqld()
         except MySQLKillSessionError:
             return False, "Failed to kill client sessions"
+        except MySQLSetInstanceOfflineModeError:
+            return False, "Failed to set instance as offline before restoring the backup"
         except MySQLStopMySQLDError:
             return False, "Failed to stop mysqld"
 

tests/unit/test_backups.py

@@ -747,10 +747,13 @@ def test_on_restore_failure(
         event.fail.assert_not_called()
 
     @patch_network_get(private_address="1.1.1.1")
+    @patch("mysql_vm_helpers.MySQL.set_instance_offline_mode")
     @patch("mysql_vm_helpers.MySQL.is_mysqld_running", return_value=True)
     @patch("mysql_vm_helpers.MySQL.kill_client_sessions")
     @patch("mysql_vm_helpers.MySQL.stop_mysqld")
-    def test_pre_restore(self, _stop_mysqld, _kill_client_sessions, _mysqld_running):
+    def test_pre_restore(
+        self, _stop_mysqld, _kill_client_sessions, _mysqld_running, _set_instance_offline_mode
+    ):
         """Test _pre_restore()."""
         success, error = self.mysql_backups._pre_restore()
 
@@ -759,12 +762,16 @@ def test_pre_restore(self, _stop_mysqld, _kill_client_sessions, _mysqld_running)
         _mysqld_running.assert_called_once()
         _stop_mysqld.assert_called_once()
         _kill_client_sessions.assert_called_once()
+        _set_instance_offline_mode.assert_called_once()
 
     @patch_network_get(private_address="1.1.1.1")
+    @patch("mysql_vm_helpers.MySQL.set_instance_offline_mode")
     @patch("mysql_vm_helpers.MySQL.is_mysqld_running", return_value=True)
     @patch("mysql_vm_helpers.MySQL.kill_client_sessions")
     @patch("mysql_vm_helpers.MySQL.stop_mysqld")
-    def test_pre_restore_failure(self, _stop_mysqld, _kill_client_sessions, _mysqld_running):
+    def test_pre_restore_failure(
+        self, _stop_mysqld, _kill_client_sessions, _mysqld_running, _set_instance_offline_mode
+    ):
         """Test failure of _pre_restore()."""
         _stop_mysqld.side_effect = MySQLStopMySQLDError()