<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-circuitbreaker-resilience4j</artifactId>
<version>3.1.1</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
<version>4.1.1</version>
</dependency>
@Service
public class MyService {
@Autowired
private RestTemplate restTemplate;
@CircuitBreaker(name = "backendService", fallbackMethod = "fallback")
public String backendService() {
// Call to some external service
return restTemplate.getForObject("http://your-backend-service-url", String.class);
}
public String fallback(Throwable throwable) {
return "Fallback response";
}
}
What problems does it solve?
Network timeout
Service unavailable
Slow response
Too many requests
Repeated failures
Temporary outage
States
Closed ↓ Open ↓ Half Open ↓ Closed
Rate Limiter
Prevent abuse.
Suppose
One customer sends
1000 requests/sec
Allowed
10 requests/sec
Reject the rest.
Bulkhead
One of my favorites.
Suppose
Payment
becomes slow.
Without Bulkhead
200 Threads
↓
Payment
↓
All threads blocked
Entire application freezes.
Bulkhead
Payment
↓
20 threads
Only
The remaining
180 threads
continue serving
Inventory
Customer
Orders
Time Limiter
Instead of waiting
30 seconds
Stop after
2 seconds
Return
Fallback.
Cache
Frequently requested data
↓
Cache
↓
Avoid calling slow service repeatedly.
Example
@Retry(name="redis")
@CircuitBreaker(name="redis")
@TimeLimiter(name="redis")
@Bulkhead(name="redis")
Resilience4j is inside your application.
Spring Boot↓Resilience4j↓Redis↓KafkaKubernetes doesn't know.
It only sees pod
