The 'Circuit Breaker' Pattern for Resilience

A Circuit Breaker prevents an application from repeatedly trying to execute an operation that's likely to fail, protecting downstream services from being overwhelmed.

When a downstream service (e.g., a database or 3rd party API) is slow or down, retrying every request can lead to a 'cascading failure'. A Circuit Breaker has three states: 1. CLOSED (Normal), 2. OPEN (Failure threshold reached, requests fail fast immediately), 3. HALF-OPEN (Testing if the service is back). Libraries like opossum are industry standards for implementing this in Node.js.