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【Spring Cloud Ribbon+Eureka】快速入门

【Spring Cloud Ribbon+Eureka】快速入门

作者: 有章 | 来源:发表于2018-10-29 14:26 被阅读0次

一.Ribbon实现客户端负载均衡

构建Spring Boot项目
1.引入pom依赖

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

2.application.yml配置

server:
  port: 9094
spring:
  application:
    name: hystrix-client
stores:
  ribbon:
    listOfServers: www.baidu.com,www.jd.com,www.163.com,www.alibaba.com

3.定义Restful接口

@RestController
@Slf4j
public class RibbonController {
    @Autowired
    LoadBalancerClient loadBalancerClient;
    @Autowired
    RestTemplate restTemplate;
   
    @GetMapping("static")
    public String stores(){
        ServiceInstance instance=loadBalancerClient.choose("stores");
        URI storesUri = URI.create(String.format("http://%s:%s", instance.getHost(), instance.getPort()));
        log.info(storesUri.toString());
        return "static";
    }
}

Ribbon的负载均衡策略

默认采用轮询的方式,RoundRobinRule(继承自AbstractLoadBalancerRule)
执行6次的结果

2018-10-29 14:39:49.226  INFO 18991 --- [nio-9094-exec-1] s.h.controller.RibbonController          : http://www.baidu.com:80
2018-10-29 14:39:49.328  INFO 18991 --- [nio-9094-exec-3] s.h.controller.RibbonController          : http://www.neteasy.com:80
2018-10-29 14:39:49.613  INFO 18991 --- [nio-9094-exec-5] s.h.controller.RibbonController          : http://www.alibaba.com:80
2018-10-29 14:39:49.806  INFO 18991 --- [nio-9094-exec-7] s.h.controller.RibbonController          : http://www.baidu.com:80
2018-10-29 14:39:49.972  INFO 18991 --- [nio-9094-exec-9] s.h.controller.RibbonController          : http://www.neteasy.com:80
2018-10-29 14:39:50.125  INFO 18991 --- [nio-9094-exec-1] s.h.controller.RibbonController          : http://www.alibaba.com:80

RandomRule(随机策略) 在index上随机,选择index对应位置的server
在配置文件application.yml加入
NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule
同时实例化对应的Bean

    @Bean
    public IRule ribbonRule(){
        return new RandomRule();
    }

执行6次的结果

2018-10-29 14:58:14.687  INFO 19120 --- [nio-9094-exec-1] s.h.controller.RibbonController          : http://www.baidu.com:80
2018-10-29 14:58:14.804  INFO 19120 --- [nio-9094-exec-3] s.h.controller.RibbonController          : http://www.neteasy.com:80
2018-10-29 14:58:15.313  INFO 19120 --- [nio-9094-exec-5] s.h.controller.RibbonController          : http://www.alibaba.com:80
2018-10-29 14:58:15.743  INFO 19120 --- [nio-9094-exec-7] s.h.controller.RibbonController          : http://www.neteasy.com:80
2018-10-29 14:58:26.410  INFO 19120 --- [io-9094-exec-10] s.h.controller.RibbonController          : http://www.baidu.com:80
2018-10-29 14:58:27.045  INFO 19120 --- [nio-9094-exec-2] s.h.controller.RibbonController          : http://www.alibaba.com:80

Ribbon服务端

将Ribbon服务端注册到Eureka注册中心中,需要引入Eureka的相应Jar包
1.pom文件

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.SR2</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

2.application.yml配置

# 9091 server1
server:
  port: 9091
spring:
  application:
    name: ribbon-server

eureka:
  client:
     serviceUrl:
        defaultZone: http://localhost:8761/eureka/,http://localhost:8762/eureka/
  instance:
    hostname: ${spring.application.name}
    instance-id: ${spring.application.name}:${server.port}
    appname: ribbon-server
# 9092 server2
server:
  port: 9092
spring:
  application:
    name: ribbon-server

eureka:
  client:
     serviceUrl:
        defaultZone: http://localhost:8761/eureka/,http://localhost:8762/eureka/
  instance:
    hostname: ${spring.application.name}
    instance-id: ${spring.application.name}:${server.port}
    appname: ribbon-server

Ribbon客户端
application.yml配置

server:
  port: 9094
spring:
  application:
    name: ribbon-client
eureka:
  client:
     serviceUrl:
        defaultZone: http://localhost:8761/eureka/,http://localhost:8762/eureka/
  instance:
    hostname: ${spring.application.name}
    instance-id: ${spring.application.name}:${server.port}
    appname: ribbon-client

启动类配置

@SpringBootApplication
@EnableCircuitBreaker
@EnableEurekaClient
public class HystrixClient2Application {
    @Bean
    @LoadBalanced
    RestTemplate restTemplate(){
        return new RestTemplate();
    }
    public static void main(String[] args) {
        SpringApplication.run(HystrixClient2Application.class, args);
    }
}

Ribbon客户端负载均衡测试

.定义如下Restful接口

@RestController
@Slf4j
public class RibbonController {
    @Autowired
    LoadBalancerClient loadBalancerClient;
    @GetMapping("loadInstance")
    public String loadInstance(){
        ServiceInstance instance=loadBalancerClient.choose("ribbon-server");
        
  log.info(instance.getServiceId()+":"+instance.getHost()+":"+instance.getPort());
        return instance.getServiceId()+":"+instance.getHost()+":"+instance.getPort();
    }

.浏览器调用http://localhost:9094/loadInstance方法,交替显示如下:

hystrix-server:hystrix-server:9091
hystrix-server:hystrix-server:9092

可以使用下面的配置禁止Eureka对Ribbon服务实例的维护实现

ribbon.eureka.enabled=false

重试机制

由于Spring Cloud Eureka实现的服务治理机制强调了cap原理的ap机制(可用性和可靠性),与zookeeper这类强调cp(一致性,可靠性)服务质量框架最大的区别就是,Eureka为了实现更高的服务可用性,牺牲了一定的一致性,在极端情况下宁愿接受故障实例也不要丢弃"健康"实例。

比如说,当服务注册中心的网络发生故障断开时候,由于所有的服务实例无法维护续约心跳,在强调ap的服务治理中将会把所有服务实例剔除掉,而Eureka则会因为超过85%的实例丢失心跳而触发保护机制,注册中心将会保留此时的所有节点,以实现服务间依然可以进行互相调用的场景,即使其中有部分故障节点,但这样做可以继续保障大多数服务的正常消费。
Spring Cloud整合了spring retry来增强RestTemplate的重试能力,对于我们开发者来说,只需要简单配置,即可完成重试策略。
pom引用

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.retry</groupId>
            <artifactId>spring-retry</artifactId>
        </dependency>

通过在application配置,使得客户端在访问到故障请求时,会重试的访问当前实例,达到maxAutoRetries次数后,尝试换一个实例继续请求。

hystrix-server:
  ribbon:
    ConnectTimeout: 250 #请求连接超时
    ReadTimeout: 1000  #请求处理的超时时间
    OkToRetryOnAllOperations: true #对所有操作请求都进行重试
    MaxAutoRetriesNextServer: 2 #切换实例的重试次数
    maxAutoRetries: 2 #对当前实例的重试次数

【参考博客】
1.https://www.jianshu.com/p/f86af82fa782
2.https://www.cnblogs.com/duanxz/p/7504947.html

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