spring-boot-resilience4j

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This skill should be used when implementing fault tolerance and resilience patterns in Spring Boot applications using the Resilience4j library. Apply this skill to add circuit breaker, retry, rate limiter, bulkhead, time limiter, and fallback mechanisms to prevent cascading failures, handle transient errors, and manage external service dependencies gracefully in microservices architectures.

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Sourcegiuseppe-trisciuoglio/developer-kit

Added on2026-02-07

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npx skill4agent add giuseppe-trisciuoglio/developer-kit spring-boot-resilience4j

SKILL.md Content

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Spring Boot Resilience4j Patterns

When to Use

To implement resilience patterns in Spring Boot applications, use this skill when:

Preventing cascading failures from external service unavailability with circuit breaker pattern
Retrying transient failures with exponential backoff
Rate limiting to protect services from overload or downstream service capacity constraints
Isolating resources with bulkhead pattern to prevent thread pool exhaustion
Adding timeout controls to async operations with time limiter
Combining multiple patterns for comprehensive fault tolerance

Resilience4j is a lightweight, composable library for adding fault tolerance without requiring external infrastructure. It provides annotation-based patterns that integrate seamlessly with Spring Boot's AOP and Actuator.

Instructions

1. Setup and Dependencies

Add Resilience4j dependencies to your project. For Maven, add to

pom.xml

xml

<dependency>
    <groupId>io.github.resilience4j</groupId>
    <artifactId>resilience4j-spring-boot3</artifactId>
    <version>2.2.0</version> // Use latest stable version
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

For Gradle, add to

build.gradle

gradle

implementation "io.github.resilience4j:resilience4j-spring-boot3:2.2.0"
implementation "org.springframework.boot:spring-boot-starter-aop"
implementation "org.springframework.boot:spring-boot-starter-actuator"

Enable AOP annotation processing with

@EnableAspectJAutoProxy

(auto-configured by Spring Boot).

2. Circuit Breaker Pattern

Apply

@CircuitBreaker

annotation to methods calling external services:

java

@Service
public class PaymentService {
    private final RestTemplate restTemplate;

    public PaymentService(RestTemplate restTemplate) {
        this.restTemplate = restTemplate;
    }

    @CircuitBreaker(name = "paymentService", fallbackMethod = "paymentFallback")
    public PaymentResponse processPayment(PaymentRequest request) {
        return restTemplate.postForObject("http://payment-api/process",
            request, PaymentResponse.class);
    }

    private PaymentResponse paymentFallback(PaymentRequest request, Exception ex) {
        return PaymentResponse.builder()
            .status("PENDING")
            .message("Service temporarily unavailable")
            .build();
    }
}

Configure in

application.yml

yaml

resilience4j:
  circuitbreaker:
    configs:
      default:
        registerHealthIndicator: true
        slidingWindowSize: 10
        minimumNumberOfCalls: 5
        failureRateThreshold: 50
        waitDurationInOpenState: 10s
    instances:
      paymentService:
        baseConfig: default

See @references/configuration-reference.md for complete circuit breaker configuration options.

3. Retry Pattern

Apply

@Retry

annotation for transient failure recovery:

java

@Service
public class ProductService {
    private final RestTemplate restTemplate;

    public ProductService(RestTemplate restTemplate) {
        this.restTemplate = restTemplate;
    }

    @Retry(name = "productService", fallbackMethod = "getProductFallback")
    public Product getProduct(Long productId) {
        return restTemplate.getForObject(
            "http://product-api/products/" + productId,
            Product.class);
    }

    private Product getProductFallback(Long productId, Exception ex) {
        return Product.builder()
            .id(productId)
            .name("Unavailable")
            .available(false)
            .build();
    }
}

Configure retry in

application.yml

yaml

resilience4j:
  retry:
    configs:
      default:
        maxAttempts: 3
        waitDuration: 500ms
        enableExponentialBackoff: true
        exponentialBackoffMultiplier: 2
    instances:
      productService:
        baseConfig: default
        maxAttempts: 5

See @references/configuration-reference.md for retry exception configuration.

4. Rate Limiter Pattern

Apply

@RateLimiter

to control request rates:

java

@Service
public class NotificationService {
    private final EmailClient emailClient;

    public NotificationService(EmailClient emailClient) {
        this.emailClient = emailClient;
    }

    @RateLimiter(name = "notificationService",
        fallbackMethod = "rateLimitFallback")
    public void sendEmail(EmailRequest request) {
        emailClient.send(request);
    }

    private void rateLimitFallback(EmailRequest request, Exception ex) {
        throw new RateLimitExceededException(
            "Too many requests. Please try again later.");
    }
}

Configure in

application.yml

yaml

resilience4j:
  ratelimiter:
    configs:
      default:
        registerHealthIndicator: true
        limitForPeriod: 10
        limitRefreshPeriod: 1s
        timeoutDuration: 500ms
    instances:
      notificationService:
        baseConfig: default
        limitForPeriod: 5

5. Bulkhead Pattern

Apply

@Bulkhead

to isolate resources. Use

type = SEMAPHORE

for synchronous methods:

java

@Service
public class ReportService {
    private final ReportGenerator reportGenerator;

    public ReportService(ReportGenerator reportGenerator) {
        this.reportGenerator = reportGenerator;
    }

    @Bulkhead(name = "reportService", type = Bulkhead.Type.SEMAPHORE)
    public Report generateReport(ReportRequest request) {
        return reportGenerator.generate(request);
    }
}

Use

type = THREADPOOL

for async/CompletableFuture methods:

java

@Service
public class AnalyticsService {
    @Bulkhead(name = "analyticsService", type = Bulkhead.Type.THREADPOOL)
    public CompletableFuture<AnalyticsResult> runAnalytics(
            AnalyticsRequest request) {
        return CompletableFuture.supplyAsync(() ->
            analyticsEngine.analyze(request));
    }
}

Configure in

application.yml

yaml

resilience4j:
  bulkhead:
    configs:
      default:
        maxConcurrentCalls: 10
        maxWaitDuration: 100ms
    instances:
      reportService:
        baseConfig: default
        maxConcurrentCalls: 5

  thread-pool-bulkhead:
    instances:
      analyticsService:
        maxThreadPoolSize: 8

6. Time Limiter Pattern

Apply

@TimeLimiter

to async methods to enforce timeout boundaries:

java

@Service
public class SearchService {
    @TimeLimiter(name = "searchService", fallbackMethod = "searchFallback")
    public CompletableFuture<SearchResults> search(SearchQuery query) {
        return CompletableFuture.supplyAsync(() ->
            searchEngine.executeSearch(query));
    }

    private CompletableFuture<SearchResults> searchFallback(
            SearchQuery query, Exception ex) {
        return CompletableFuture.completedFuture(
            SearchResults.empty("Search timed out"));
    }
}

Configure in

application.yml

yaml

resilience4j:
  timelimiter:
    configs:
      default:
        timeoutDuration: 2s
        cancelRunningFuture: true
    instances:
      searchService:
        baseConfig: default
        timeoutDuration: 3s

7. Combining Multiple Patterns

Stack multiple patterns on a single method for comprehensive fault tolerance:

java

@Service
public class OrderService {
    @CircuitBreaker(name = "orderService")
    @Retry(name = "orderService")
    @RateLimiter(name = "orderService")
    @Bulkhead(name = "orderService")
    public Order createOrder(OrderRequest request) {
        return orderClient.createOrder(request);
    }
}

Execution order: Retry → CircuitBreaker → RateLimiter → Bulkhead → Method

All patterns should reference the same named configuration instance for consistency.

8. Exception Handling and Monitoring

Create a global exception handler using

@RestControllerAdvice

java

@RestControllerAdvice
public class ResilienceExceptionHandler {

    @ExceptionHandler(CallNotPermittedException.class)
    @ResponseStatus(HttpStatus.SERVICE_UNAVAILABLE)
    public ErrorResponse handleCircuitOpen(CallNotPermittedException ex) {
        return new ErrorResponse("SERVICE_UNAVAILABLE",
            "Service currently unavailable");
    }

    @ExceptionHandler(RequestNotPermitted.class)
    @ResponseStatus(HttpStatus.TOO_MANY_REQUESTS)
    public ErrorResponse handleRateLimited(RequestNotPermitted ex) {
        return new ErrorResponse("TOO_MANY_REQUESTS",
            "Rate limit exceeded");
    }

    @ExceptionHandler(BulkheadFullException.class)
    @ResponseStatus(HttpStatus.SERVICE_UNAVAILABLE)
    public ErrorResponse handleBulkheadFull(BulkheadFullException ex) {
        return new ErrorResponse("CAPACITY_EXCEEDED",
            "Service at capacity");
    }
}

Enable Actuator endpoints for monitoring resilience patterns in

application.yml

yaml

management:
  endpoints:
    web:
      exposure:
        include: health,metrics,circuitbreakers,retries,ratelimiters
  endpoint:
    health:
      show-details: always
  health:
    circuitbreakers:
      enabled: true
    ratelimiters:
      enabled: true

Access monitoring endpoints:

```
GET /actuator/health
```
- Overall health including resilience patterns
```
GET /actuator/circuitbreakers
```
- Circuit breaker states
```
GET /actuator/metrics
```
- Custom resilience metrics

Best Practices

Always provide fallback methods: Ensure graceful degradation with meaningful responses rather than exceptions
Use exponential backoff for retries: Prevent overwhelming recovering services with aggressive backoff (
```
exponentialBackoffMultiplier: 2
```
)
Choose appropriate failure thresholds: Set
```
failureRateThreshold
```
between 50-70% depending on acceptable error rates
Use constructor injection exclusively: Never use field injection for Resilience4j dependencies
Enable health indicators: Set
```
registerHealthIndicator: true
```
for all patterns to integrate with Spring Boot health
Separate failure vs. client errors: Retry only transient errors (network timeouts, 5xx); skip 4xx and business exceptions
Size bulkheads based on load: Calculate thread pool and semaphore sizes from expected concurrent load and latency
Monitor and adjust: Continuously review metrics and adjust timeouts/thresholds based on production behavior
Document fallback behavior: Make fallback logic clear and predictable to users and maintainers

Common Mistakes

Refer to

references/testing-patterns.md

for:

Testing circuit breaker state transitions
Simulating transient failures with WireMock
Validating fallback method signatures
Avoiding common misconfiguration errors

Refer to

references/configuration-reference.md

for:

Complete property reference for all patterns
Configuration validation rules
Exception handling configuration

References and Examples

Complete property reference and configuration patterns
Unit and integration testing strategies
Real-world e-commerce service example using all patterns
Resilience4j Documentation
Spring Boot Actuator Skill - Monitoring resilience patterns with Actuator

spring-boot-resilience4j

NPX Install

Tags

SKILL.md Content

Spring Boot Resilience4j Patterns

When to Use

Instructions

1. Setup and Dependencies

2. Circuit Breaker Pattern

3. Retry Pattern

4. Rate Limiter Pattern

5. Bulkhead Pattern

6. Time Limiter Pattern

7. Combining Multiple Patterns

8. Exception Handling and Monitoring

Best Practices

Common Mistakes

References and Examples