circuit-breaker-pattern

To prevent cascading failures in TypeScript, wrap external API calls in a circuit breaker that short-circuits failing requests. Configure a sliding-window failure threshold to stop repeated calls to unhealthy dependencies and protect overall system availability.

The half-open state in a circuit breaker works by sending limited probe requests to a previously failing dependency to verify recovery. If probes succeed, the circuit closes; if they fail, it reopens, preventing full load from hitting the still-unhealthy service.

Yes, you can configure separate failure thresholds per dependency. Circuit breakers support per-dependency tuning for sliding windows, recovery timeouts, and probe counts, allowing distinct resilience policies for external APIs, databases, and third-party integrations.

Fallback strategies for circuit breaker fault tolerance include returning cached values, safe defaults, or queueing requests for later processing. These graceful degradation methods ensure your application remains functional when external dependencies fail or timeout.

Add observability to a circuit breaker by emitting state-change events and metrics for monitoring dashboards and alerts. Track transitions between closed, open, and half-open states alongside failure counts to trigger alerts when external dependencies degrade.

Avoid using a circuit breaker when external service calls require strict consistency or when transient failures are better handled by simple retries alone. Circuit breakers are designed for repeated, sustained failures where fast-failing protects availability better than continuing to attempt calls.