[MISC] Suppress alias creation error (#284)

* Suppress alias creation error

* Add unit test

src/charm.py

@@ -216,14 +216,12 @@ def _on_install(self, _) -> None:
             self.unit.status = BlockedStatus("failed to install snap packages")
             return
 
-        # Try to disable pgbackrest service
         try:
             cache = snap.SnapCache()
             selected_snap = cache[PGBOUNCER_SNAP_NAME]
             selected_snap.alias("psql")
-        except snap.SnapError as e:
-            error_message = "Failed to stop and disable pgbackrest snap service"
-            logger.exception(error_message, exc_info=e)
+        except snap.SnapError:
+            logger.warning("Unable to create alias")
 
         self.create_instance_directories()
         self.render_pgb_config()

tests/unit/test_charm.py

@@ -57,6 +57,7 @@ def setUp(self):
     def use_caplog(self, caplog):
         self._caplog = caplog
 
+    @patch("charm.logger.warning")
     @patch("builtins.open", unittest.mock.mock_open())
     @patch("charm.snap.SnapCache")
     @patch("charm.PgBouncerCharm._install_snap_packages")
@@ -80,6 +81,7 @@ def test_on_install(
         _stop,
         _install,
         _snap_cache,
+        _warning,
     ):
         pg_snap = _snap_cache.return_value["charmed-pgbouncer"]
         self.charm.on.install.emit()
@@ -98,6 +100,13 @@ def test_on_install(
 
         self.assertIsInstance(self.harness.model.unit.status, WaitingStatus)
 
+        # Log warning if alias fails
+        pg_snap.alias.side_effect = snap.SnapError
+
+        self.charm.on.install.emit()
+
+        _warning.assert_called_once_with("Unable to create alias")
+
     @patch(
         "relations.backend_database.BackendDatabaseRequires.ready",
         new_callable=PropertyMock,