fix(charm): disable snap services on teardown, not just stop

stop() leaves the snap services enabled, so a mid-teardown restart of the unit could re-enable them and re-grab the storage mounts before Juju finishes unmounting. stop(disable=True) prevents that.

Signed-off-by: Marcelo Henrique Neppel <marcelo.neppel@canonical.com>

Author: marceloneppel

src/charm.py

@@ -2576,7 +2576,9 @@ def _on_storage_detaching(self, _) -> None:
         self._observer.stop_observer()
         self._rotate_logs.stop_log_rotation()
         try:
-            snap.SnapCache()[charm_refresh.snap_name()].stop()
+            # Disable too, so a mid-teardown restart of the unit can't re-enable the
+            # services and re-grab the storage mounts before Juju finishes unmounting.
+            snap.SnapCache()[charm_refresh.snap_name()].stop(disable=True)
         except snap.SnapError:
             logger.exception("Failed to stop charmed-postgresql snap services")
 

tests/unit/test_charm.py

@@ -145,7 +145,8 @@ def test_on_storage_detaching(harness):
         _selected_snap.stop.assert_not_called()
 
         # Full teardown (no units remain): release the storage by stopping the
-        # background processes and all the snap services.
+        # background processes and disabling (so a mid-teardown restart can't
+        # re-grab the mount) all the snap services.
         _planned_units.return_value = 0
         for storage_name in ("archive", "data", "logs", "temp"):
             _stop_observer.reset_mock()
@@ -157,7 +158,7 @@ def test_on_storage_detaching(harness):
 
             _stop_observer.assert_called_once_with()
             _stop_log_rotation.assert_called_once_with()
-            _selected_snap.stop.assert_called_once_with()
+            _selected_snap.stop.assert_called_once_with(disable=True)
 
 
 def test_patroni_scrape_config(harness):