Circuit Breaker Status in Health Checks

Circuit Breaker Health Integration

Including circuit breaker states in health checks provides visibility into your service's resilience mechanisms and helps explain degraded behavior.

Response Component

{
  "circuitBreakers": {
    "payment-gateway": {
      "status": "closed",
      "failureRate": "2.5%",
      "failureThreshold": "50%",
      "successCount": 195,
      "failureCount": 5,
      "lastFailure": null
    },
    "email-service": {
      "status": "open",
      "failureRate": "75%",
      "failureThreshold": "50%",
      "successCount": 25,
      "failureCount": 75,
      "lastFailure": "2024-01-15T10:28:00Z",
      "nextRetryAt": "2024-01-15T10:30:00Z"
    },
    "inventory-api": {
      "status": "half-open",
      "failureRate": "0%",
      "testRequestsAllowed": 3,
      "testRequestsCompleted": 1
    }
  }
}

Circuit Breaker States

State	Meaning	Health Impact
Closed	Normal operation, requests flow through	UP
Open	Failures exceeded threshold, requests blocked	DEGRADED or DOWN
Half-open	Testing if service recovered	DEGRADED

Mapping to Health Status

function deriveStatus(breakers) {
  const states = Object.values(breakers).map(b => b.status);

  if (states.some(s => s === 'open')) {
    // Check if the open circuit is for a critical service
    const criticalOpen = Object.entries(breakers)
      .some(([name, b]) => b.status === 'open' && isCritical(name));
    return criticalOpen ? 'DOWN' : 'DEGRADED';
  }

  if (states.some(s => s === 'half-open')) return 'DEGRADED';
  return 'UP';
}

Why Expose Circuit Breaker State

1. Debugging: Explains why certain features are unavailable
2. Monitoring: Track circuit breaker transitions over time
3. Alerting: Alert when circuits open on critical dependencies
4. Capacity planning: Frequent circuit opens indicate under-provisioned dependencies

Best Practice

Separate critical and non-critical circuit breakers in your health mapping. An open circuit on your payment gateway is DOWN. An open circuit on your analytics service is DEGRADED at most.