Перейти до основного вмісту

Circuit Breakers & Retries

This document describes how to implement circuit breakers and retry policies to enhance service resilience in Spring Boot microservices.

1. Overview​

Circuit breakers prevent a system from repeatedly trying a failing service, while retries offer a second chance for transient failures. Together, they guard against resource exhaustion and cascading failures.

2. Retry Strategy​

Spring Retry (with annotations)​

@Retryable(
  value = { HttpServerErrorException.class },
  maxAttempts = 3,
  backoff = @Backoff(delay = 2000, multiplier = 2)
)
public String callPaymentService() {
    return restTemplate.getForObject(PAYMENT_URL, String.class);
}

RetryTemplate (Programmatic)​

RetryTemplate retryTemplate = new RetryTemplate();
// configure policy...
String result = retryTemplate.execute(ctx -> externalService.call());

3. Circuit Breaker Strategy​

Resilience4j​

Add dependency:

<dependency>
  <groupId>io.github.resilience4j</groupId>
  <artifactId>resilience4j-spring-boot3</artifactId>
</dependency>

Configuration:

resilience4j.circuitbreaker.instances.paymentService:
  registerHealthIndicator: true
  slidingWindowSize: 10
  failureRateThreshold: 50
  waitDurationInOpenState: 10s
  permittedNumberOfCallsInHalfOpenState: 3

Annotation-based usage:

@CircuitBreaker(name = "paymentService", fallbackMethod = "fallback")
public String callPayment() {
    return webClient.get().uri("/pay").retrieve().bodyToMono(String.class).block();
}

Fallback method:

public String fallback(Throwable t) {
    return "Payment service unavailable. Please try later.";
}

4. Metrics and Observability​

  • Use Micrometer + Prometheus to monitor circuit breaker states.
  • Trigger alerts on high failure rates.

5. Best Practices​

  • Combine circuit breakers with timeouts and bulkheads.
  • Separate circuit breaker configs per external dependency.
  • Avoid retry storms (apply jitter and limits).
  • Document Version: 1.0
  • Date: 2025-06-24
  • Author: ArturChernets