Use on[] instead of getattr()

src/kubernetes_charm.py

@@ -32,7 +32,7 @@ def __init__(self, *args) -> None:
         super().__init__(*args)
         self.framework.observe(self.on.install, self._on_install)
         self.framework.observe(
-            getattr(self.on, "mysql_router_pebble_ready"), self._on_mysql_router_pebble_ready
+            self.on[rock.CONTAINER_NAME].pebble_ready, self._on_workload_container_pebble_ready
         )
         # TODO VM TLS: Move to super class
         self.tls = relations.tls.RelationEndpoint(self)
@@ -132,7 +132,7 @@ def _on_install(self, _) -> None:
             logger.exception("Failed to patch k8s service")
             raise
 
-    def _on_mysql_router_pebble_ready(self, _) -> None:
+    def _on_workload_container_pebble_ready(self, _) -> None:
         self.unit.set_workload_version(self.get_workload(event=None).version)
         self.reconcile_database_relations()
 

src/rock.py

@@ -13,6 +13,7 @@
 
 logger = logging.getLogger(__name__)
 
+CONTAINER_NAME = "mysql-router"
 _UNIX_USERNAME = "mysql"
 
 
@@ -68,7 +69,7 @@ class Rock(container.Container):
 
     def __init__(self, *, unit: ops.Unit) -> None:
         super().__init__(mysql_router_command="mysqlrouter", mysql_shell_command="mysqlsh")
-        self._container = unit.get_container("mysql-router")
+        self._container = unit.get_container(CONTAINER_NAME)
 
     @property
     def ready(self) -> bool: