chore(docker): close neomodel driver on gunicorn worker exit

docker/gunicorn.conf.py

@@ -34,3 +34,19 @@ def post_worker_init(worker):
             logging.getLogger("library.apps").warning(
                 "Startup probe crashed: %s", exc, exc_info=True
             )
+
+
+def worker_exit(server, worker):
+    # Neomodel lazily creates a neo4j.Driver on first cypher_query and
+    # holds it for the process lifetime. Newer neo4j drivers warn (and
+    # will eventually fail to clean up) if the driver is destroyed
+    # without an explicit close. Close it here so each gunicorn worker
+    # shuts down cleanly.
+    try:
+        from neomodel import db
+
+        db.close_connection()
+    except Exception as exc:
+        logging.getLogger("neomodel").warning(
+            "Failed to close neomodel driver on worker exit: %s", exc
+        )