Set schema url for Swagger via env variable (#2823)

# What this PR does

## Which issue(s) this PR fixes

## Checklist

- [ ] Unit, integration, and e2e (if applicable) tests updated
- [ ] Documentation added (or `pr:no public docs` PR label added if not
required)
- [ ] `CHANGELOG.md` updated (or `pr:no changelog` PR label added if not
required)

docker-compose-developer.yml

@@ -3,7 +3,7 @@ version: "3.9"
 x-labels: &oncall-labels
   - "com.grafana.oncall.env=dev"
 
-x-user: &oncall-user "appuser"
+x-user: &oncall-user "root"
 
 x-oncall-build: &oncall-build-args
   context: ./engine

engine/settings/base.py

@@ -260,11 +260,18 @@ SPECTACULAR_SETTINGS = {
     "SERVE_INCLUDE_SCHEMA": False,
     # OTHER SETTINGS
     "PREPROCESSING_HOOKS": [
-        "engine.included_path.custom_preprocessing_hook"
+        "engine.included_path.custom_preprocessing_hook"  # Custom hook to include only paths from SPECTACULAR_INCLUDED_PATHS
-    ],  # Custom hook to include only paths from SPECTACULAR_INCLUDED_PATHS
+    ],
     "SERVE_URLCONF": ("apps.api.urls"),
-    "SWAGGER_UI_SETTINGS": {"supportedSubmitMethods": []},  # Disable "Try it out" button for all endpoints
+    "SWAGGER_UI_SETTINGS": {
+        "supportedSubmitMethods": [],  # Disable "Try it out" button for all endpoints
+    },
+    "SERVE_PUBLIC": False,
 }
+# Use custom scheme if env var exists
+SWAGGER_UI_SETTINGS_URL = os.getenv("SWAGGER_UI_SETTINGS_URL")
+if SWAGGER_UI_SETTINGS_URL:
+    SPECTACULAR_SETTINGS["SWAGGER_UI_SETTINGS"]["url"] = SWAGGER_UI_SETTINGS_URL
 
 SPECTACULAR_INCLUDED_PATHS = [
     "/features",

engine/settings/prod_without_db.py

@@ -160,4 +160,5 @@ REST_FRAMEWORK = {
     ),
     "DEFAULT_AUTHENTICATION_CLASSES": [],
     "DEFAULT_RENDERER_CLASSES": ("rest_framework.renderers.JSONRenderer",),
+    "DEFAULT_SCHEMA_CLASS": "drf_spectacular.openapi.AutoSchema",
 }