Summary
API gateways are the natural enforcement point for circuit breakers: the gateway intercepts all inbound requests, tracks per-service error rates, and can open circuits to specific backend services while returning cached responses or 503s to callers: without any changes to individual service code.
Evidence
- ·Kong's circuit breaker plugin implements the pattern at the gateway level: zero service code changes
- ·AWS API Gateway integrates with Lambda and returns 502/503 when backend circuit is open
- ·Istio DestinationRule outlierDetection implements circuit breaking at the service mesh (gateway) layer
- ·Netflix Zuul (API gateway) implements hystrix circuit breakers at the gateway for all inbound traffic
- ·Envoy proxy implements upstream circuit breaking (max_connections, max_pending_requests)
Operational Context
- ·Gateway-level circuit breakers provide a single configuration point for all service circuit breakers
- ·Gateway can return cached responses when circuit is open: transparent degradation instead of error
- ·Circuit state changes (open/half-open/closed) should be emitted as metrics to enable SRE dashboards
Tradeoffs
- ·Gateway-level circuit breaking is coarser-grained than per-call circuit breaking in application code
- ·A centralized gateway is itself a potential single point of failure: requires high-availability deployment
- ·Gateway circuit breakers may not capture partial failures within a service (e.g., only one endpoint degraded)
Evidence grounding
Grounded, 5 supporting itemsAPI gateway circuit breaking is documented in Kong, AWS API Gateway, and Istio as a standard feature. The architectural combination is widely used in production microservice deployments.