SpringCloud Zuul实现负载均衡和熔断机制

柔情只为你懂 2022-04-18 02:07 186阅读 0赞

# 一、场景 #

笔者就Zuul网关下实现其负载均衡与熔断机制(雪崩)进行实践，前提是已经导入zuul相关依赖

springboot版本：1.5.9.RELEASE

springcloud版本：Dalston.SR5

<dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-zuul</artifactId>
            </dependency>
            <dependency>
                <groupId>com.netflix.zuul</groupId>
                <artifactId>zuul-core</artifactId>
                <version>1.3.0</version>
            </dependency>
    </dependencies>

--------------------

# 二、场景实现 #

**1、在网关的配置文件中配置ribbon(负载均衡)和hystrix(熔断机制)**

#熔断机制
    hystrix:
      command:
        default:
          execution:
            isolation:
              thread:
                timeoutInMilliseconds: 6000
    
    #负载均衡
    ribbon:
      ConnectionTimeout: 500
      ReadTimeout: 2000
    #端口
    server:
      port: 8080
    spring:
      #该配置文件中的配置，对应的服务名称是wc-gateway
      application:
        name: wc-gateway
      profiles:
        active: dev
    #服务网关配置
    zuul:
      host:
        connect-timeout-millis: 60000
        socket-timeout-millis: 60000
      #路由规则
      routes:
        api:
          path: /api/user/**
          serviceId: wc-client-user

其实ribbon的真实值=(ConnectionTimeout+ReadTimeout)\*2，该值最好小于hystrix的timeoutInMilliseconds的值，因为如果大于其值会失去负载均衡(ribbon)的重试机会，而直接熔断

**2、验证负载均衡**

因为zuul下自带了hystrix，ribbon相关jar包，所有现在已经实现了负载均衡和熔断机制，接下来进行验证

在client服务下编写controller，测试负载均衡

package top.wingcloud.controller;
    
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    /**
     * @author: linjie
     * @description: 用户服务请求处理控制器
     * @create: 2018/11/06 09:16
     */
    @RestController
    public class UserController {
        @Value("${server.port}")
        private int port;
    
        @RequestMapping("index")
        public String index(){
            return "Hello World!"+port;
        }
    }

依次启动注册中心、配置中心、client服务、修改端口再次启动client服务、服务网关

根据网关的路由，访问同一个路由，发现启动的两个不同端口的client服务交替执行

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dfbGludXg_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dfbGludXg_size_16_color_FFFFFF_t_70 1][]出现该情况即实现了负载均衡

3、验证熔断机制

在网关服务中需要写ZuulFallbackProvider的实现类

package top.wingcloud.filter;
    
    import org.springframework.cloud.netflix.zuul.filters.route.ZuulFallbackProvider;
    import org.springframework.http.HttpHeaders;
    import org.springframework.http.HttpStatus;
    import org.springframework.http.MediaType;
    import org.springframework.http.client.ClientHttpResponse;
    import org.springframework.stereotype.Component;
    
    import java.io.ByteArrayInputStream;
    import java.io.IOException;
    import java.io.InputStream;
    
    /**
     * @author: linjie
     * @description:错误拦截回显，熔断
     * @create: 2018/10/11 20:01
     */
    @Component
    public class ApiFallbackProvider implements ZuulFallbackProvider{
    
        @Override
        public String getRoute() {
            //设置熔断的服务名
            //如果是所有服务则设置为*
            return "wc-client-user";
        }
    
        @Override
        public ClientHttpResponse fallbackResponse() {
            return new ClientHttpResponse() {
                @Override
                public HttpStatus getStatusCode() throws IOException {
                    return HttpStatus.OK;
                }
    
                @Override
                public int getRawStatusCode() throws IOException {
                    return 200;
                }
    
                @Override
                public String getStatusText() throws IOException {
                    return "{code:0,message:service error =_=}";
                }
    
                @Override
                public void close() {
    
                }
    
                @Override
                public InputStream getBody() throws IOException {
                    return new ByteArrayInputStream(getStatusText().getBytes());
                }
    
                @Override
                public HttpHeaders getHeaders() {
                    HttpHeaders headers = new HttpHeaders();
                    headers.setContentType(MediaType.APPLICATION_JSON);
                    return headers;
                }
            };
        }
    }

这个时候关闭client所有服务，再次访问之前的网关路由

出现了getStatusText()中的提示，即实现了熔断机制

![20181107000052683.png][]好了，zuul下的负载均衡和熔断已经实现，时间不早了，赶紧睡觉！

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dfbGludXg_size_16_color_FFFFFF_t_70 1]: /images/20220418/4fe82bf3153b442f9d6553ef01e213d9.png
[20181107000052683.png]: /images/20220418/053547e2631d4261bbde407c8cc830d3.png