Fix frontend not connecting to api

frontend/charm/src/charm.py

@@ -7,7 +7,6 @@
 """Test Observer frontend charm."""
 
 import logging
-import sys
 from typing import Tuple
 
 import ops
@@ -31,7 +30,7 @@ def __init__(self, *args):
         self.pebble_service_name = "test-observer-frontend"
         self.container = self.unit.get_container("frontend")
 
-        self.framework.observe(self.on.frontend_pebble_ready, self._on_frontend_pebble_ready)
+        self.framework.observe(self.on.frontend_pebble_ready, self._update_layer_and_restart)
         self.framework.observe(self.on.config_changed, self._on_config_changed)
         self.framework.observe(
             self.on.test_observer_rest_api_relation_joined,
@@ -56,12 +55,6 @@ def _setup_ingress(self):
             service_port=int(self.config["port"]),
         )
 
-    def _on_frontend_pebble_ready(self, event: ops.PebbleReadyEvent):
-        container = event.workload
-        container.add_layer("frontend", self._pebble_layer, combine=True)
-        container.replan()
-        self.unit.status = ops.ActiveStatus()
-
     def _on_config_changed(self, event):
         is_valid, reason = self._config_is_valid(self.config)
 
@@ -162,29 +155,35 @@ def _update_layer_and_restart(self, event):
         self.unit.status = MaintenanceStatus(f"Updating {self.pebble_service_name} layer")
 
         if self.container.can_connect():
-            self.container.push(
-                "/etc/nginx/sites-available/test-observer-frontend",
-                self.nginx_config(base_uri=self._api_url),
-                make_dirs=True,
-            )
-            self.container.add_layer(self.pebble_service_name, self._pebble_layer, combine=True)
-            self.container.restart(self.pebble_service_name)
-            self.unit.status = ActiveStatus()
+            api_url = self._api_url
+            if api_url:
+                self.container.push(
+                    "/etc/nginx/sites-available/test-observer-frontend",
+                    self.nginx_config(base_uri=api_url),
+                    make_dirs=True,
+                )
+                self.container.add_layer(
+                    self.pebble_service_name, self._pebble_layer, combine=True
+                )
+                self.container.replan()
+                self.unit.status = ActiveStatus()
+            else:
+                self._handle_no_api_relation()
         else:
             self.unit.status = WaitingStatus("Waiting for Pebble for API to set available state")
 
     @property
-    def _api_url(self):
+    def _api_url(self) -> str | None:
         api_relation = self.model.get_relation("test-observer-rest-api")
 
         if api_relation is None:
             self._handle_no_api_relation()
-            sys.exit()
+            return
 
         relation_data = api_relation.data[api_relation.app]
         if not relation_data:
             self.unit.status = WaitingStatus("Waiting for test observer api relation data")
-            sys.exit()
+            return
 
         hostname = relation_data["hostname"]
         port = relation_data["port"]

frontend/charm/tests/unit/test_charm.py

@@ -16,28 +16,12 @@ def setUp(self):
         self.addCleanup(self.harness.cleanup)
         self.harness.begin()
 
-    def test_pebble_ready(self):
-        expected_plan = {
-            "services": {
-                "test-observer-frontend": {
-                    "override": "replace",
-                    "summary": "nginx",
-                    "command": "nginx -g 'daemon off;'",
-                    "startup": "enabled",
-                }
-            },
-        }
-
+    def test_pebble_ready_no_relation(self):
         self.harness.container_pebble_ready("frontend")
-        updated_plan = self.harness.get_container_pebble_plan("frontend").to_dict()
-
-        self.assertEqual(expected_plan, updated_plan)
-
-        service = self.harness.model.unit.get_container("frontend").get_service(
-            "test-observer-frontend"
+        self.assertEqual(
+            self.harness.model.unit.status,
+            ops.MaintenanceStatus("test-observer-rest-api relation not connected."),
         )
-        self.assertTrue(service.is_running())
-        self.assertEqual(self.harness.model.unit.status, ops.ActiveStatus())
 
     def test_relating(self):
         harness = ops.testing.Harness(TestObserverFrontendCharm)