Add settings to allow detaching integrations server (#3203)

To run a detached integrations server:
1. Set env var `DETACHED_INTEGRATIONS_SERVER=True`
2. Run engine with the `integrations_urls.py` root url conf
(e.g. `ROOT_URLCONF=engine.integrations_urls python manage.py runserver
0.0.0.0:8081`)

engine/engine/integrations_urls.py

@@ -0,0 +1,9 @@
+from django.urls import URLPattern, URLResolver, include, path
+
+from .urls import paths_to_work_even_when_maintenance_mode_is_active
+
+urlpatterns: list[URLPattern | URLResolver] = paths_to_work_even_when_maintenance_mode_is_active
+
+urlpatterns += [
+    path("integrations/v1/", include("apps.integrations.urls", namespace="integrations")),
+]

engine/engine/urls.py

@@ -15,20 +15,24 @@
 """
 from django.conf import settings
 from django.conf.urls.static import static
-from django.urls import include, path
+from django.urls import URLPattern, URLResolver, include, path
 
 from .views import HealthCheckView, MaintenanceModeStatusView, ReadinessCheckView, StartupProbeView
 
-paths_to_work_even_when_maintenance_mode_is_active = [
+paths_to_work_even_when_maintenance_mode_is_active: list[URLPattern | URLResolver] = [
     path("", HealthCheckView.as_view()),
     path("health/", HealthCheckView.as_view()),
     path("ready/", ReadinessCheckView.as_view()),
     path("startupprobe/", StartupProbeView.as_view()),
-    path("integrations/v1/", include("apps.integrations.urls", namespace="integrations")),
     path("api/internal/v1/maintenance-mode-status", MaintenanceModeStatusView.as_view()),
 ]
 
-urlpatterns = [
+if not settings.DETACHED_INTEGRATIONS_SERVER:
+    paths_to_work_even_when_maintenance_mode_is_active += [
+        path("integrations/v1/", include("apps.integrations.urls", namespace="integrations")),
+    ]
+
+urlpatterns: list[URLPattern | URLResolver] = [
     *paths_to_work_even_when_maintenance_mode_is_active,
     path("api/gi/v1/", include("apps.api_for_grafana_incident.urls", namespace="api-gi")),
     path("api/internal/v1/", include("apps.api.urls", namespace="api-internal")),

engine/settings/base.py

@@ -373,7 +373,7 @@ class DatabaseTypes:
     },
 }
 
-ROOT_URLCONF = "engine.urls"
+ROOT_URLCONF = os.environ.get("ROOT_URLCONF", "engine.urls")
 
 TEMPLATES = [
     {
@@ -831,3 +831,5 @@ class BrokerTypes:
 ZVONOK_POSTBACK_STATUS = os.getenv("ZVONOK_POSTBACK_STATUS", "status")
 ZVONOK_POSTBACK_USER_CHOICE = os.getenv("ZVONOK_POSTBACK_USER_CHOICE", None)
 ZVONOK_POSTBACK_USER_CHOICE_ACK = os.getenv("ZVONOK_POSTBACK_USER_CHOICE_ACK", None)
+
+DETACHED_INTEGRATIONS_SERVER = getenv_boolean("DETACHED_INTEGRATIONS_SERVER", default=False)