add pebble plan validation

src/charm.py

@@ -11,7 +11,7 @@
 
 from charms.nginx_ingress_integrator.v0.nginx_route import require_nginx_route
 from jinja2 import Environment, FileSystemLoader
-from ops import main
+from ops import main, pebble
 from ops.charm import CharmBase
 from ops.model import ActiveStatus, BlockedStatus, MaintenanceStatus, WaitingStatus
 from ops.pebble import CheckStatus
@@ -158,13 +158,33 @@ def _on_update_status(self, event):
             return
 
         container = self.unit.get_container(self.name)
+        valid_pebble_plan = self._validate_pebble_plan(container)
+        if not valid_pebble_plan:
+            self._update(event)
+            return
 
         check = container.get_check("up")
         if check.status != CheckStatus.UP:
             self.unit.status = MaintenanceStatus("Status check: DOWN")
             return
 
-        self.unit.status = ActiveStatus()
+        message = "auth enabled" if self.config["auth-enabled"] else ""
+        self.unit.status = ActiveStatus(message)
+
+    def _validate_pebble_plan(self, container):
+        """Validate Temporal UI pebble plan.
+
+        Args:
+            container: application container
+
+        Returns:
+            bool of pebble plan validity
+        """
+        try:
+            plan = container.get_plan().to_dict()
+            return bool(plan and plan["services"].get(self.name, {}).get("on-check-failure"))
+        except pebble.ConnectionError:
+            return False
 
     @log_event_handler(logger)
     def _on_ui_relation_joined(self, event):

tests/unit/test_charm.py

@@ -20,6 +20,7 @@
 
 APP_NAME = "temporal-ui"
 UI_PORT = "8080"
+mock_incomplete_pebble_plan = {"services": {"temporal-ui": {"override": "replace"}}}
 
 
 class TestCharm(TestCase):
@@ -242,6 +243,37 @@ def test_update_status_down(self):
 
         self.assertEqual(harness.model.unit.status, MaintenanceStatus("Status check: DOWN"))
 
+    def test_incomplete_pebble_plan(self):
+        """The charm re-applies the pebble plan if incomplete."""
+        harness = self.harness
+        simulate_lifecycle(harness)
+
+        container = harness.model.unit.get_container("temporal-ui")
+        container.add_layer("temporal-ui", mock_incomplete_pebble_plan, combine=True)
+        harness.charm.on.update_status.emit()
+
+        self.assertEqual(
+            harness.model.unit.status,
+            MaintenanceStatus("replanning application"),
+        )
+        plan = harness.get_container_pebble_plan("temporal-ui").to_dict()
+        assert plan != mock_incomplete_pebble_plan
+
+    @mock.patch("charm.TemporalUiK8SOperatorCharm._validate_pebble_plan", return_value=True)
+    def test_missing_pebble_plan(self, mock_validate_pebble_plan):
+        """The charm re-applies the pebble plan if missing."""
+        harness = self.harness
+        simulate_lifecycle(harness)
+
+        mock_validate_pebble_plan.return_value = False
+        harness.charm.on.update_status.emit()
+        self.assertEqual(
+            harness.model.unit.status,
+            MaintenanceStatus("replanning application"),
+        )
+        plan = harness.get_container_pebble_plan("temporal-ui").to_dict()
+        assert plan is not None
+
 
 def simulate_lifecycle(harness):
     """Simulate a healthy charm life-cycle.