2.12 Retry and Resilience (Retry / Resilience4j)

External API, DB, and message broker calls can fail due to transient errors. Use Retry and Circuit Breaker to absorb failures and limit blast radius.

Reference: Spring Boot 3.2.x, spring-retry or Resilience4j

1. Spring Retry (@Retryable)

implementation 'org.springframework.retry:spring-retry'

@SpringBootApplication
@EnableRetry
public class Application { ... }

@Service
public class PaymentClient {

    @Retryable(
        retryFor = { RestClientException.class },
        maxAttempts = 3,
        backoff = @Backoff(delay = 1000, multiplier = 2)
    )
    public PaymentResult callExternalApi(PaymentRequest req) {
        return restTemplate.postForObject(...);
    }

    @Recover  // called after all retries are exhausted
    public PaymentResult recover(RestClientException e, PaymentRequest req) {
        log.error("Payment API call failed, fallback", e);
        return PaymentResult.failed("Temporary error");
    }
}

• retryFor: Only retry on these exceptions
• maxAttempts: Maximum number of attempts
• backoff: Wait time (delay ms, increasing by multiplier)
• @Recover: Signature must match (Exception, method args...)

2. Resilience4j — Circuit Breaker

Use Resilience4j to block calls for a period on consecutive failures, protecting resources.

implementation 'io.github.resilience4j:resilience4j-spring-boot3'

resilience4j:
  circuitbreaker:
    instances:
      paymentApi:
        registerHealthIndicator: true
        slidingWindowSize: 10
        minimumNumberOfCalls: 5
        failureRateThreshold: 50
        waitDurationInOpenState: 10s

@Service
public class PaymentService {

    private final CircuitBreaker circuitBreaker;
    private final PaymentClient client;

    public PaymentService(CircuitBreakerRegistry registry, PaymentClient client) {
        this.circuitBreaker = registry.circuitBreaker("paymentApi");
        this.client = client;
    }

    public PaymentResult pay(PaymentRequest req) {
        return circuitBreaker.executeSupplier(() -> client.callExternalApi(req));
    }
}

• failureRateThreshold: Circuit opens (OPEN) when failure rate exceeds this value
• waitDurationInOpenState: After this duration in OPEN state, transitions to HALF_OPEN to probe

3. Retry + Circuit Breaker

Resilience4j allows registering both Retry and CircuitBreaker together. A common pattern is to retry a few times with Retry first, then open the CircuitBreaker if the failure rate is still high.

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tip

Limit retried exceptions with retryFor and do not retry business errors (4xx etc.). Adjust external dependency timeouts together with RestTemplate/WebClient settings.