Spring Cloud 学习纪要九：Sleuth
Spring Cloud Sleuth：链路跟踪
Spring Cloud Sleuth是一种分布式追踪解决方案，它兼容Zipkin。微服务架构由于服务单元数量众多、调用关系杂乱、业务复杂，如果出现了错误和异常很难去定位，所以微服务架构中，必须实现分布式链路追踪，去跟进一个请求到底有哪些服务参与，参与的顺序又是怎样的，让每个请求步骤直观可见，而 Sleuth + Zipkin 便可以帮助我们做到这样的事情。
| 开发环境 | 版本 |
|---|---|
| IDEA | 2018.2.6 |
| JDK | 1.8 |
| Spring Boot | 2.0.6 |
| Spring Cloud | Finchley.SR2 |
| Docker | 18.09.0 |
| Zipkin | – |
特别注意：本系列纪要环环相扣，建议从第一节开始阅读 点击跳转
Zipkin 容器搭建
docker run -d -p 9411:9411 openzipkin/zipkin
Docker下执行一个命令就能运行Zipkin容器，具体视个人PC情况而定，开启服务后访问http://localhost:9411/zipkin/可以看到如下界面。
依赖添加
provider项目和consumer项目添加如下Maven依赖，特别注意：，因为我这边一直下载不到2.0.2的包，不知道是不是我的IDE的问题，将版本改为2.1.0.M2。
<dependency>
<groupId>org.springframework.cloudgroupId>
<artifactId>spring-cloud-starter-zipkinartifactId>
<version>2.1.0.M2version>
dependency>
配置文件修改
provider项目和consumer项目添加如下配置：
spring:
zipkin:
base-url: http://localhost:9411/
sender:
type: web
sleuth:
sampler:
probability: 1
logging:
level:
org.springframework.cloud.openfeign: debug
链路跟踪测试
访问consumer的接口http://localhost:8091/hello/consume?num=1，发现consumer项目控制台会打印如下日志，注意cde8ad1de4f90441。
2018-11-26 21:26:23.946 INFO [consumer,cde8ad1de4f90441,e3c14617dff44d76,true] 12488 --- [trix-provider-1] s.c.a.AnnotationConfigApplicationContext : Refreshing SpringClientFactory-provider: startup date [Mon Nov 26 21:26:23 CST 2018]; parent: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@777d0bc3
2018-11-26 21:26:24.009 INFO [consumer,cde8ad1de4f90441,e3c14617dff44d76,true] 12488 --- [trix-provider-1] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2018-11-26 21:26:24.236 INFO [consumer,cde8ad1de4f90441,e3c14617dff44d76,true] 12488 --- [trix-provider-1] c.netflix.config.ChainedDynamicProperty : Flipping property: provider.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2018-11-26 21:26:24.254 INFO [consumer,cde8ad1de4f90441,e3c14617dff44d76,true] 12488 --- [trix-provider-1] c.n.u.concurrent.ShutdownEnabledTimer : Shutdown hook installed for: NFLoadBalancer-PingTimer-provider
2018-11-26 21:26:24.279 INFO [consumer,cde8ad1de4f90441,e3c14617dff44d76,true] 12488 --- [trix-provider-1] c.netflix.loadbalancer.BaseLoadBalancer : Client: provider instantiated a LoadBalancer: DynamicServerListLoadBalancer:{NFLoadBalancer:name=provider,current list of Servers=[],Load balancer stats=Zone stats: {},Server stats: []}ServerList:null
2018-11-26 21:26:24.284 INFO [consumer,cde8ad1de4f90441,e3c14617dff44d76,true] 12488 --- [trix-provider-1] c.n.l.DynamicServerListLoadBalancer : Using serverListUpdater PollingServerListUpdater
2018-11-26 21:26:24.313 INFO [consumer,cde8ad1de4f90441,e3c14617dff44d76,true] 12488 --- [trix-provider-1] c.netflix.config.ChainedDynamicProperty : Flipping property: provider.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2018-11-26 21:26:24.315 INFO [consumer,cde8ad1de4f90441,e3c14617dff44d76,true] 12488 --- [trix-provider-1] c.n.l.DynamicServerListLoadBalancer : DynamicServerListLoadBalancer for client provider initialized: DynamicServerListLoadBalancer:{NFLoadBalancer:name=provider,current list of Servers=[192.168.99.1:8081],Load balancer stats=Zone stats: {defaultzone=[Zone:defaultzone; Instance count:1; Active connections count: 0; Circuit breaker tripped count: 0; Active connections per server: 0.0;]
},Server stats: [[Server:192.168.99.1:8081; Zone:defaultZone; Total Requests:0; Successive connection failure:0; Total blackout seconds:0; Last connection made:Thu Jan 01 08:00:00 CST 1970; First connection made: Thu Jan 01 08:00:00 CST 1970; Active Connections:0; total failure count in last (1000) msecs:0; average resp time:0.0; 90 percentile resp time:0.0; 95 percentile resp time:0.0; min resp time:0.0; max resp time:0.0; stddev resp time:0.0]
]}ServerList:org.springframework.cloud.netflix.ribbon.eureka.DomainExtractingServerList@7900120d
访问Zipkin页面，查询consumer项目的调用链：
点击某一行即可查看该调用的详细信息，包括其traceIdcde8ad1de4f90441。
总结
至此《Spring Cloud 学习纪要》系列博客就结束了，本系列博客介绍了包含服务治理组件Eureka、服务通信组件Feign、负载均衡组件Ribbon、配置中心组件Config、消息总线组件Bus、消息驱动组件Stream、统一网关组件Zuul、熔断降级组件Hystrix、链路跟踪组件Sleuth，此系列博客只适合入门小白，是一套极简教程，更多知识待您亲自探索。
| 组件 | 功能 | 同类框架 |
|---|---|---|
| Spring Cloud Eureka | 服务治理 | ZooKeeper、Consul |
| Spring Cloud Feign | 服务通信 | Retrofit、OKHttp、HttpClient |
| Spring Cloud Ribbon | 负载均衡 | Nginx |
| Spring Cloud Config | 配置中心 | Consul |
| Spring Cloud Bus | 消息总线 | |
| Spring Cloud Stream | 消息驱动 | |
| Spring Cloud Zuul | 统一网关 | Janus、Spring Cloud Gateway |
| Spring Cloud Hystrix | 熔断降级 | |
| Spring Cloud Sleuth | 链路跟踪 | Zipkin、Pinpoint |
附件
本系列纪要博客源码：跳转到github
本系列纪要博客配置文件：跳转到github