Add service dependencies feature flag (#5420)

# What this PR does

Adds `service_dependencies` feature flag

## Which issue(s) this PR closes

Related to https://github.com/grafana/oncall-private/issues/2977

## Checklist

- [x] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] Added the relevant release notes label (see labels prefixed w/
`release:`). These labels dictate how your PR will
    show up in the autogenerated release notes.

engine/apps/api/tests/test_alert_group.py

@@ -2421,7 +2421,9 @@ def test_alert_group_affected_services(
     make_user_for_organization,
     make_user_auth_headers,
     make_alert_group_label_association,
+    settings,
 ):
+    settings.FEATURE_SERVICE_DEPENDENCIES_ENABLED = True
     _, token, alert_groups = alert_group_internal_api_setup
     resolved_ag, ack_ag, new_ag, silenced_ag = alert_groups
     organization = new_ag.channel.organization
@@ -2454,3 +2456,29 @@ def test_alert_group_affected_services(
         },
     ]
     assert response.json() == expected
+
+
+@pytest.mark.django_db
+def test_alert_group_service_dependencies_feature_not_enabled(
+    alert_group_internal_api_setup,
+    make_user_for_organization,
+    make_user_auth_headers,
+    make_alert_group_label_association,
+    settings,
+):
+    settings.FEATURE_SERVICE_DEPENDENCIES_ENABLED = False
+    _, token, alert_groups = alert_group_internal_api_setup
+    _, _, new_ag, _ = alert_groups
+    organization = new_ag.channel.organization
+    user = make_user_for_organization(organization)
+
+    # set firing alert group service label
+    make_alert_group_label_association(organization, new_ag, key_name="service_name", value_name="service-a")
+
+    client = APIClient()
+    url = reverse("api-internal:alertgroup-filter-affected-services")
+
+    url = f"{url}?service=service-1"
+    response = client.get(url, format="json", **make_user_auth_headers(user, token))
+
+    assert response.status_code == status.HTTP_404_NOT_FOUND

engine/apps/api/views/alert_group.py

@@ -916,6 +916,8 @@ class AlertGroupView(
     @action(methods=["get"], detail=False)
     def filter_affected_services(self, request):
         """Given a list of service names, return the ones that have active alerts."""
+        if not settings.FEATURE_SERVICE_DEPENDENCIES_ENABLED:
+            raise NotFound
         organization = self.request.auth.organization
         services = self.request.query_params.getlist("service", [])
         url_builder = UIURLBuilder(organization)

engine/apps/api/views/features.py

@@ -26,6 +26,7 @@ class Feature(enum.StrEnum):
     GRAFANA_ALERTING_V2 = "grafana_alerting_v2"
     LABELS = "labels"
     GOOGLE_OAUTH2 = "google_oauth2"
+    SERVICE_DEPENDENCIES = "service_dependencies"
 
 
 class FeaturesAPIView(APIView):
@@ -72,4 +73,7 @@ class FeaturesAPIView(APIView):
         if settings.GOOGLE_OAUTH2_ENABLED:
             enabled_features.append(Feature.GOOGLE_OAUTH2)
 
+        if settings.FEATURE_SERVICE_DEPENDENCIES_ENABLED:
+            enabled_features.append(Feature.SERVICE_DEPENDENCIES)
+
         return enabled_features

engine/settings/base.py

@@ -76,6 +76,7 @@ FEATURE_ALERT_GROUP_SEARCH_ENABLED = getenv_boolean("FEATURE_ALERT_GROUP_SEARCH_
 FEATURE_ALERT_GROUP_SEARCH_CUTOFF_DAYS = getenv_integer("FEATURE_ALERT_GROUP_SEARCH_CUTOFF_DAYS", default=None)
 FEATURE_NOTIFICATION_BUNDLE_ENABLED = getenv_boolean("FEATURE_NOTIFICATION_BUNDLE_ENABLED", default=True)
 FEATURE_DECLARE_INCIDENT_STEP_ENABLED = getenv_boolean("FEATURE_DECLARE_INCIDENT_STEP_ENABLED", default=False)
+FEATURE_SERVICE_DEPENDENCIES_ENABLED = getenv_boolean("FEATURE_SERVICE_DEPENDENCIES_ENABLED", default=False)
 
 TWILIO_API_KEY_SID = os.environ.get("TWILIO_API_KEY_SID")
 TWILIO_API_KEY_SECRET = os.environ.get("TWILIO_API_KEY_SECRET")