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Connectum API Reference / @connectum/interceptors / circuit-breaker / createCircuitBreakerInterceptor

Function: createCircuitBreakerInterceptor() ​

createCircuitBreakerInterceptor(options?): Interceptor

Defined in: circuit-breaker.ts:94

Create circuit breaker interceptor

Prevents cascading failures by opening circuit after consecutive failures. When circuit is open, requests fail immediately without calling the service.

Circuit States:

  • Closed (normal): Requests pass through
  • Open (failing): Requests rejected immediately
  • Half-Open (testing): Single request allowed to test recovery

By default only infrastructure errors trip the breaker (see defaultFailurePredicate); business codes like invalid_argument or not_found never do. Customize via CircuitBreakerOptions.failurePredicate.

The circuit breaker is an outbound/client-side pattern: it protects the caller from a sick upstream and gives that upstream room to recover. On a server's inbound stack it degenerates into error-rate load shedding — prefer timeout + bulkhead for inbound protection.

Parameters ​

options? ​

CircuitBreakerOptions = {}

Circuit breaker options

Returns ​

Interceptor

ConnectRPC interceptor

Examples ​

Client-side usage with transport (recommended placement)

typescript
import { createConnectTransport } from '@connectrpc/connect-node';
import { createCircuitBreakerInterceptor } from '@connectum/interceptors';

const transport = createConnectTransport({
  baseUrl: 'http://localhost:5000',
  interceptors: [
    createCircuitBreakerInterceptor({
      threshold: 5,           // Open after 5 consecutive failures
      halfOpenAfter: 30000,   // Try again after 30 seconds
    }),
  ],
});

Custom failure classification (compose with the default)

typescript
import { Code, ConnectError } from '@connectrpc/connect';

createCircuitBreakerInterceptor({
  // Never trip on upstream per-client rate limits
  failurePredicate: (err, def) =>
    def(err) && !(err instanceof ConnectError && err.code === Code.ResourceExhausted),
});