Booking synchronization: calls to the partner API time out intermittently

Kounouz Voyages, an online travel agency based in Casablanca, continuously synchronizes availability and bookings with the partner hotel booking hub api.centrale-riad.ma. The sync-resa service runs on a managed instance group mig-sync of VMs without an external IP in europe-west1; they reach the Internet through the Cloud NAT gateway nat-ew1 (router rt-ew1).

On Monday, to absorb the high season, the team scaled the group from 2 to 6 VMs and raised each worker's concurrency from 50 to 200 simultaneous requests. Since then, the logs are filling up with ETIMEDOUT, bookings remain “pending” and the call center is swamped with complaints. The partner swears nothing has changed on its side.

You are on your workstation with gcloud configured on kounouz-prod-7734 (number 593017284466).