Node.js Circuit Breaker Pattern in Production: Opossum, Fallbacks, and Resilience Engineering

Node.js Circuit Breaker Pattern in Production: Opossum, Fallbacks, and Resilience Engineering Distributed systems fail. Not occasionally — constantly. Third-party APIs go down, databases become overloaded, downstream microservices return 500s. The question isn't whether your dependencies will fail; it's whether your Node.js service survives gracefully when they do. The circuit breaker pattern is one of the most important resilience primitives in production engineering. Without it, a failing downstream service can cascade through your entire stack: requests pile up, thread pools exhaust, memory grows, and your healthy service becomes an unhealthy one. With a well-implemented circuit breaker, failures are isolated, degraded functionality is served via fallbacks, and the failing service gets time to recover. This article covers everything you need to implement circuit breakers in production Node.js: the state machine, opossum (the standard Node.js library), fallback strategies, health che