服务限流、降级、熔断-SpringCloud

本文所使用的组件：Nacos（服务中心和注册中心）、OpenFeign（服务调用）、Sentinel（限流、降级）、Hystrix（熔断）

项目结构：

1. service-provider：提供服务的微服务。

2. service-consumer：消费服务的微服务。

1. 添加依赖

在两个服务的pom.xml文件中添加Spring Cloud Alibaba、Nacos、Sentinel、Hystrix和OpenFeign的依赖。

<dependencies>
    <!-- Spring Cloud Alibaba Nacos Discovery -->
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    </dependency>
    <!-- Spring Cloud Alibaba Sentinel -->
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
    </dependency>
    <!-- Hystrix -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
    </dependency>
    <!-- Spring Cloud OpenFeign -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>
    <!-- Spring Boot Web Starter -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>

2. Docker-compose.yml文件

创建docker-compose.yml文件，启动Nacos和Sentinel。

version: '3'
services:
  nacos-server:
    image: nacos/nacos-server:latest
    container_name: nacos-server
    ports:
      - "8848:8848"
    environment:
      - MODE=standalone
      - SPRING_DATASOURCE_PLATFORM=mysql
  sentinel-server:
    image: apache/incubating-sentinel-dashboard:latest
    container_name: sentinel-server
    ports:
      - "8080:8080"
      - "8719:8719"

• 部署在云服务中需要打开8080、8848端口，端口冲突可以更换端口。

3. service-provider（提供服务的微服务）

3.1 启动类

创建启动类并添加nacos注册客户端。

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableFeignClients
public class ServiceProviderApplication {

    public static void main(String[] args) {
        SpringApplication.run(ServiceProviderApplication.class, args);
    }
}

3.2 控制器

创建控制器提供服务。

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ServiceController {

    @GetMapping("/provider")
    public String provider() {
        return "Hello from Service Provider";
    }
}

4. service-consumer（消费服务的微服务）

4.1 OpenFeign客户端

创建Feign客户端用于调用service-provider。

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

@FeignClient(name = "service-provider", fallback = ServiceFallback.class)
public interface ServiceClient {
    @GetMapping("/provider")
    String provider();
}

@Component
public class ServiceFallback implements ServiceClient {
    @Override
    public String provider() {
        // 服务降级逻辑
        return "Fallback response from Service Consumer";
    }
}

4.2 控制器

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ConsumerController {

    private final ServiceClient serviceClient;

    public ConsumerController(ServiceClient serviceClient) {
        this.serviceClient = serviceClient;
    }

    @GetMapping("/consumer")
    @HystrixCommand(commandKey = "consumerCommand", fallbackMethod = "fallback")
    @SentinelResource(value = "serviceClientCall", blockHandler = "blockHandler")
    public String consumer() {
        return serviceClient.provider();
    }

    public String fallback() {
        // 熔断降级逻辑
        return "Service is down, hystrix fallback";
    }

    public String blockHandler(BlockException ex) {
        // Sentinel降级逻辑
        return "Service is blocked by Sentinel";
    }
}

• @HystrixCommand注解用于指定熔断器的命令键和降级方法，@SentinelResource注解用于指定资源名和降级方法。

5. application.yml

在两个服务添加application.yml文件。

spring:
  cloud:
    nacos:
      discovery:
        server-addr: nacos-server:8848
      config:
        server-addr: nacos-server:8848
    sentinel:
      transport:
        dashboard: sentinel-server:8080
      datasource:
        ds1:
          type: file
          file:
            filePath: /path/to/your/sentinel/rules
  hystrix:
    command:
      default:
        execution:
          isolation:
            strategy: THREAD
          thread:
            timeoutInMilliseconds: 3000

• filePath:文件路径

6. 配置规则

在Sentinel Dashboard（http://localhost:8080）中添加限流规则：

资源名：serviceClientCall
限流模式：QPS
阈值：10

总结：上述为一套完整的服务治理流程，对于某些场景下可以使用guava框架去实现单体限流。主要学习思想，本文所使用的组件可替换为其他具有相关功能的组件。

不积跬步，无以至千里 --- xiaokai