SRE Daily Dashboard

Certified Kubernetes Administrator (CKA)

Issuer: The Linux Foundation / CNCF

Formal Definition

An architectural pattern used in software development to detect failures and encapsulate the logic of preventing a failure from constantly recurring, during maintenance, temporary external system outages, or unexpected latency.

Typical Use Case

Preventing cascading failures in microservice architectures by stopping requests to an unresponsive downstream dependency and immediately returning a fallback response.

Conceptual Code Example

```ts
class CircuitBreaker {
  private state: 'CLOSED' | 'OPEN' | 'HALF_OPEN' = 'CLOSED';
  private failureCount = 0;
  private nextAttempt = 0;

  async execute(fn: () => Promise) {
    if (this.state === 'OPEN' && Date.now() < this.nextAttempt) {
      return 'Fallback content (Cached)';
    }
    try {
      const result = await fn();
      this.success();
      return result;
    } catch (err) {
      this.fail();
      throw err;
    }
  }
}
```