Master Reactive Feign in Spring Boot 2.7: A Hands‑On Guide

Introduction

Feign‑reactive is a framework for building reactive microservices in Spring Cloud, offering a concise Feign style, support for the Reactive programming model, asynchronous non‑blocking remote calls, seamless Spring Cloud integration, and extensibility through custom interceptors, encoders, and decoders.

Dependency Management

<dependency>
  <groupId>com.playtika.reactivefeign</groupId>
  <artifactId>feign-reactor-spring-configuration</artifactId>
  <version>3.3.0</version>
</dependency>
<dependency>
  <groupId>com.playtika.reactivefeign</groupId>
  <artifactId>feign-reactor-cloud</artifactId>
  <version>3.3.0</version>
</dependency>
<dependency>
  <groupId>com.playtika.reactivefeign</groupId>
  <artifactId>feign-reactor-webclient</artifactId>
  <version>3.3.0</version>
</dependency>

Practical Example

Remote Interface

@GetMapping("/demos/info/{id}")
public Object info(@PathVariable("id") Integer id) throws Exception {
    TimeUnit.SECONDS.sleep(3);
    Map<String, Object> result = new HashMap<>();
    result.put("code", 0);
    result.put("data", id);
    result.put("message", "success");
    return result;
}

Enable Reactive Feign

@EnableReactiveFeignClients
public class AppFeignReactorApplication {}

Reactive Feign Interface Definition

@ReactiveFeignClient(
    url = "http://localhost:8088/demos",
    name = "demoReactorFeign"
)
public interface DemoReactorFeign {
    @GetMapping("/info/{id}")
    Mono<Object> info(@PathVariable("id") Integer id);
}

Test Call

@Resource
private DemoReactorFeign demoReactorFeign;

@GetMapping("/{id}")
public Object info(@PathVariable("id") Integer id) {
    return this.demoReactorFeign.info(id);
}

Fallback Configuration

@ReactiveFeignClient(
    url = "http://localhost:8088/demos",
    name = "demoReactorFeign",
    fallback = DemoReactorFeignFallback.class,
    configuration = {DemoReactorFeignConfig.class}
)
public interface DemoReactorFeign {}

Fallback Implementation

public class DemoReactorFeignFallback implements DemoReactorFeign {
    @Override
    public Mono<Object> info(Integer id) {
        return Mono.just("请求失败");
    }
}

Custom Configuration

public class DemoReactorFeignConfig {
    @Bean
    public DemoReactorFeignFallback demoReactorFeignFallback() {
        return new DemoReactorFeignFallback();
    }
}

When a remote call fails or times out, the fallback defined above will be executed.

Timeout Configuration

reactive:
  feign:
    client:
      config:
        demoReactorFeign:
          options:
            connectTimeoutMillis: 2000
            readTimeoutMillis: 2000

Load Balancer Configuration

reactive:
  feign:
    loadbalancer:
      enabled: true

Circuit Breaker Configuration

reactive:
  feign:
    circuit:
      breaker:
        enabled: true

To activate the circuit breaker, add the following dependency:

<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-circuitbreaker-reactor-resilience4j</artifactId>
</dependency>

Conclusion: Feign‑reactive works similarly to OpenFeign but uses reactive annotations; it enables asynchronous non‑blocking remote calls, improving performance and throughput of Spring Cloud applications.