Node.js Circuit Breaker Pattern in Production: Prevent Cascading Failures with Opossum

Node.js Circuit Breaker Pattern in Production: Prevent Cascading Failures with Opossum Your payment service starts timing out at 3am. Every inbound request to your checkout API fires an HTTP call to the payment provider — and each one hangs for 30 seconds before failing. Your Node.js event loop isn't blocked in the traditional sense, but your promise queue fills with pending async operations. Connection pool slots get consumed. Memory climbs. Eventually, request queuing kicks in at the load balancer level, latency spikes site-wide, and a single struggling downstream service has taken your entire application offline. This is the cascading failure problem. The circuit breaker pattern exists to stop it. A circuit breaker sits in front of any external call — HTTP, database, queue, cache — and monitors its failure rate. When failures exceed a threshold, the breaker "trips" and stops forwarding calls to the failing service entirely. Callers get fast failures instead of hung promises. The dep