--- description: Spring Cloud microservices patterns with gateway, discovery, and resilience name: spring-microservices type: skill --- # Spring Microservices Spring Cloud microservices patterns with gateway, discovery, and resilience ## # Spring Microservices Skill Build distributed microservices architectures using Spring Cloud Gateway, service discovery, configuration management, and resilience patterns. ## # Spring Microservices Skill Build distributed microservices architectures using Spring Cloud Gateway, service discovery, configuration management, and resilience patterns. ## Process ### Step 1: Spring Cloud Gateway Configure API Gateway for routing and cross-cutting concerns: ```java // GatewayApplication.java @SpringBootApplication public class GatewayApplication { public static void main(String[] args) { SpringApplication.run(GatewayApplication.class, args); } } // application.yml spring: cloud: gateway: routes: - id: user-service uri: lb://user-service predicates: - Path=/api/users/** filters: - StripPrefix=1 - name: RequestRateLimiter args: redis-rate-limiter.replenishRate: 10 redis-rate-limiter.burstCapacity: 20 - id: order-service uri: lb://order-service predicates: - Path=/api/orders/** filters: - StripPrefix=1 - name: CircuitBreaker args: name: orderServiceCircuitBreaker fallbackUri: forward:/fallback/orders // GatewayConfig.java @Configuration public class GatewayConfig { @Bean public RouteLocator customRouteLocator(RouteLocatorBuilder builder) { return builder.routes() .route("user-service", r -> r .path("/api/users/**") .filters(f -> f .addRequestHeader("X-Gateway-Request", "true") .retry(retryConfig -> retryConfig .setRetries(3) .setMethods(HttpMethod.GET) .setBackoff(Duration.ofMillis(100), Duration.ofSeconds(2), 2, false) ) ) .uri("lb://user-service")) .build(); } @Bean public GlobalFilter customGlobalFilter() { return (exchange, chain) -> { ServerHttpRequest request = exchange.getRequest(); ServerHttpRequest modifiedRequest = request.mutate() .header("X-Gateway-Timestamp", String.valueOf(System.currentTimeMillis())) .build(); return chain.filter(exchange.mutate().request(modifiedRequest).build()); }; } } ``` ### Step 2: Service Discovery with Eureka Set up Eureka server and client registration: ```java // EurekaServerApplication.java @SpringBootApplication @EnableEurekaServer public class EurekaServerApplication { public static void main(String[] args) { SpringApplication.run(EurekaServerApplication.class, args); } } // eureka-server application.yml server: port: 8761 eureka: instance: hostname: localhost client: register-with-eureka: false fetch-registry: false // UserServiceApplication.java (Client) @SpringBootApplication @EnableEurekaClient public class UserServiceApplication { public static void main(String[] args) { SpringApplication.run(UserServiceApplication.class, args); } } // user-service application.yml spring: application: name: user-service eureka: client: service-url: defaultZone: http://localhost:8761/eureka/ instance: prefer-ip-address: true ``` ### Step 3: Config Server Centralized configuration management: ```java // ConfigServerApplication.java @SpringBootApplication @EnableConfigServer public class ConfigServerApplication { public static void main(String[] args) { SpringApplication.run(ConfigServerApplication.class, args); } } // config-server application.yml spring: cloud: config: server: git: uri: https://github.com/org/config-repo search-paths: '{application}' clone-on-start: true // Client application.yml spring: cloud: config: uri: http://localhost:8888 name: user-service profile: dev ``` ### Step 4: Circuit Breaker with Resilience4j Implement circuit breaker pattern: ```java // UserServiceClient.java @Service public class UserServiceClient { private final RestTemplate restTemplate; private final CircuitBreaker circuitBreaker; public UserServiceClient(RestTemplate restTemplate, CircuitBreakerRegistry circuitBreakerRegistry) { this.restTemplate = restTemplate; this.circuitBreaker = circuitBreakerRegistry.circuitBreaker("userService"); } @CircuitBreaker(name = "userService", fallbackMethod = "getUserFallback") public User getUser(Long id) { return circuitBreaker.executeSupplier(() -> restTemplate.getForObject("http://user-service/api/users/{id}", User.class, id) ); } public User getUserFallback(Long id, Exception ex) { return User.builder() .id(id) .name("Fallback User") .email("fallback@example.com") .build(); } } // Resilience4jConfig.java @Configuration public class Resilience4jConfig { @Bean public CircuitBreakerRegistry circuitBreakerRegistry() { CircuitBreakerConfig config = CircuitBreakerConfig.custom() .failureRateThreshold(50) .waitDurationInOpenState(Duration.ofMillis(1000)) .slidingWindowSize(10) .build(); return CircuitBreakerRegistry.of(config); } @Bean public TimeLimiterRegistry timeLimiterRegistry() { return TimeLimiterRegistry.of(TimeLimiterConfig.custom() .timeoutDuration(Duration.ofSeconds(3)) .build()); } } ``` ### Step 5: Distributed Tracing Set up Micrometer Tracing with Zipkin: ```java // pom.xml io.micrometer micrometer-tracing-bridge-brave io.zipkin.reporter2 zipkin-reporter-brave // application.yml management: tracing: sampling: probability: 1.0 zipkin: tracing: endpoint: http://localhost:9411/api/v2/spans // TracingConfig.java @Configuration public class TracingConfig { @Bean public Sender sender() { return OkHttpSender.create("http://localhost:9411/api/v2/spans"); } @Bean public AsyncReporter spanReporter() { return AsyncReporter.create(sender()); } } ``` ### Step 6: Event-Driven with Spring Cloud Stream Implement event-driven microservices: ```java // OrderService.java @Service public class OrderService { private final StreamBridge streamBridge; public OrderService(StreamBridge streamBridge) { this.streamBridge = streamBridge; } public void createOrder(Order order) { // Process order orderRepository.save(order); // Publish event streamBridge.send("orderCreated-out-0", OrderCreatedEvent.builder() .orderId(order.getId()) .userId(order.getUserId()) .totalAmount(order.getTotalAmount()) .timestamp(Instant.now()) .build()); } } // NotificationService.java @SpringBootApplication @EnableBinding(Sink.class) public class NotificationService { @StreamListener(Sink.INPUT) public void handleOrderCreated(OrderCreatedEvent event) { // Send notification notificationService.sendEmail(event.getUserId(), "Order " + event.getOrderId() + " created"); } } // application.yml spring: cloud: stream: bindings: orderCreated-out-0: destination: order-created binder: kafka input: destination: order-created group: notification-service kafka: binder: brokers: localhost:9092 ``` ```java // GatewayApplication.java @SpringBootApplication public class GatewayApplication { public static void main(String[] args) { SpringApplication.run(GatewayApplication.class, args); } } // application.yml spring: cloud: gateway: routes: - id: user-service uri: lb://user-service predicates: - Path=/api/users/** filters: - StripPrefix=1 - name: RequestRateLimiter args: redis-rate-limiter.replenishRate: 10 redis-rate-limiter.burstCapacity: 20 - id: order-service uri: lb://order-service predicates: - Path=/api/orders/** filters: - StripPrefix=1 - name: CircuitBreaker args: name: orderServiceCircuitBreaker fallbackUri: forward:/fallback/orders // GatewayConfig.java @Configuration public class GatewayConfig { @Bean public RouteLocator customRouteLocator(RouteLocatorBuilder builder) { return builder.routes() .route("user-service", r -> r .path("/api/users/**") .filters(f -> f .addRequestHeader("X-Gateway-Request", "true") .retry(retryConfig -> retryConfig .setRetries(3) .setMethods(HttpMethod.GET) .setBackoff(Duration.ofMillis(100), Duration.ofSeconds(2), 2, false) ) ) .uri("lb://user-service")) .build(); } @Bean public GlobalFilter customGlobalFilter() { return (exchange, chain) -> { ServerHttpRequest request = exchange.getRequest(); ServerHttpRequest modifiedRequest = request.mutate() .header("X-Gateway-Timestamp", String.valueOf(System.currentTimeMillis())) .build(); return chain.filter(exchange.mutate().request(modifiedRequest).build()); }; } } ``` ```java // EurekaServerApplication.java @SpringBootApplication @EnableEurekaServer public class EurekaServerApplication { public static void main(String[] args) { SpringApplication.run(EurekaServerApplication.class, args); } } // eureka-server application.yml server: port: 8761 eureka: instance: hostname: localhost client: register-with-eureka: false fetch-registry: false // UserServiceApplication.java (Client) @SpringBootApplication @EnableEurekaClient public class UserServiceApplication { public static void main(String[] args) { SpringApplication.run(UserServiceApplication.class, args); } } // user-service application.yml spring: application: name: user-service eureka: client: service-url: defaultZone: http://localhost:8761/eureka/ instance: prefer-ip-address: true ``` ```java // ConfigServerApplication.java @SpringBootApplication @EnableConfigServer public class ConfigServerApplication { public static void main(String[] args) { SpringApplication.run(ConfigServerApplication.class, args); } } // config-server application.yml spring: cloud: config: server: git: uri: https://github.com/org/config-repo search-paths: '{application}' clone-on-start: true // Client application.yml spring: cloud: config: uri: http://localhost:8888 name: user-service profile: dev ``` ```java // UserServiceClient.java @Service public class UserServiceClient { private final RestTemplate restTemplate; private final CircuitBreaker circuitBreaker; public UserServiceClient(RestTemplate restTemplate, CircuitBreakerRegistry circuitBreakerRegistry) { this.restTemplate = restTemplate; this.circuitBreaker = circuitBreakerRegistry.circuitBreaker("userService"); } @CircuitBreaker(name = "userService", fallbackMethod = "getUserFallback") public User getUser(Long id) { return circuitBreaker.executeSupplier(() -> restTemplate.getForObject("http://user-service/api/users/{id}", User.class, id) ); } public User getUserFallback(Long id, Exception ex) { return User.builder() .id(id) .name("Fallback User") .email("fallback@example.com") .build(); } } // Resilience4jConfig.java @Configuration public class Resilience4jConfig { @Bean public CircuitBreakerRegistry circuitBreakerRegistry() { CircuitBreakerConfig config = CircuitBreakerConfig.custom() .failureRateThreshold(50) .waitDurationInOpenState(Duration.ofMillis(1000)) .slidingWindowSize(10) .build(); return CircuitBreakerRegistry.of(config); } @Bean public TimeLimiterRegistry timeLimiterRegistry() { return TimeLimiterRegistry.of(TimeLimiterConfig.custom() .timeoutDuration(Duration.ofSeconds(3)) .build()); } } ``` ```java // pom.xml io.micrometer micrometer-tracing-bridge-brave io.zipkin.reporter2 zipkin-reporter-brave // application.yml management: tracing: sampling: probability: 1.0 zipkin: tracing: endpoint: http://localhost:9411/api/v2/spans // TracingConfig.java @Configuration public class TracingConfig { @Bean public Sender sender() { return OkHttpSender.create("http://localhost:9411/api/v2/spans"); } @Bean public AsyncReporter spanReporter() { return AsyncReporter.create(sender()); } } ``` ```java // OrderService.java @Service public class OrderService { private final StreamBridge streamBridge; public OrderService(StreamBridge streamBridge) { this.streamBridge = streamBridge; } public void createOrder(Order order) { // Process order orderRepository.save(order); // Publish event streamBridge.send("orderCreated-out-0", OrderCreatedEvent.builder() .orderId(order.getId()) .userId(order.getUserId()) .totalAmount(order.getTotalAmount()) .timestamp(Instant.now()) .build()); } } // NotificationService.java @SpringBootApplication @EnableBinding(Sink.class) public class NotificationService { @StreamListener(Sink.INPUT) public void handleOrderCreated(OrderCreatedEvent event) { // Send notification notificationService.sendEmail(event.getUserId(), "Order " + event.getOrderId() + " created"); } } // application.yml spring: cloud: stream: bindings: orderCreated-out-0: destination: order-created binder: kafka input: destination: order-created group: notification-service kafka: binder: brokers: localhost:9092 ``` ## Output - Microservices with service discovery integration - API Gateway with routing and filtering - Centralized configuration server - Circuit breaker implementations - Distributed tracing setup - Event-driven communication patterns ## Best Practices - Use API Gateway for single entry point and cross-cutting concerns - Implement service discovery for dynamic service location - Use Config Server for centralized configuration management - Apply circuit breakers to prevent cascading failures - Implement distributed tracing for observability - Use event-driven patterns for loose coupling - Implement retry logic with exponential backoff - Use rate limiting to protect services - Monitor service health with health checks - Implement graceful degradation with fallbacks ## Related - Knowledge: `knowledge/spring-microservices-patterns.json` - Skill: `spring-boot-development` for service implementation - Skill: `spring-observability` for monitoring and metrics ## Prerequisites > [!IMPORTANT] > Requirements: > - Knowledge: spring-microservices-patterns.json

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