feat: maintenance mode for web

app/config.py

@@ -638,6 +638,8 @@ def getRateLimitFromConfig(
 
 STORE_TRANSACTIONAL_EMAILS = "STORE_TRANSACTIONAL_EMAILS" in os.environ
 
+MAINTENANCE_MODE = "MAINTENANCE_MODE" in os.environ
+
 EVENT_WEBHOOK = os.environ.get("EVENT_WEBHOOK", None)
 
 # We want it disabled by default, so only skip if defined

maintenance_app.py

@@ -0,0 +1,45 @@
+from app import config
+
+from flask import Flask, request, jsonify, render_template
+from werkzeug.middleware.proxy_fix import ProxyFix
+
+
+def create_maintenance_app() -> Flask:
+    """Minimal Flask app used when MAINTENANCE_MODE is set at startup.
+    Requires no database connection."""
+    app = Flask(__name__)
+    app.wsgi_app = ProxyFix(app.wsgi_app, x_for=1, x_host=1)
+
+    @app.route("/health", methods=["GET"])
+    def healthcheck():
+        return "success", 200
+
+    @app.before_request
+    def maintenance():
+        if (
+            request.path.startswith("/health")
+            or request.path.startswith("/admin")
+            or request.path.startswith("/static")
+        ):
+            return
+        if request.path.startswith("/api/"):
+            return (
+                jsonify(
+                    {"error": "Service is under maintenance, please try again later"}
+                ),
+                503,
+            )
+        return render_template("error/503.html"), 503
+
+    @app.context_processor
+    def inject_stage_and_region():
+        import arrow
+
+        now = arrow.now()
+        return dict(
+            YEAR=now.year,
+            NOW=now,
+            URL=config.URL,
+        )
+
+    return app