SpringCloud（九）：配置中心（消息总线）【Finchley版】

spring 1年前 ⋅ 173 阅读

我们在 Spring Cloud（七）：配置中心（Git、Refresh） 中讲到，如果需要客户端获取到最新的配置信息需要执行refresh，我们可以利用 Webhook 的机制每次提交代码发送请求来刷新客户端，当客户端越来越多的时候，需要每个客户端都执行一遍，这种方案就不太适合了。使用 Spring Cloud Bus 可以完美解决这一问题。

Spring Cloud Bus

Spring Cloud Bus 通过轻量消息代理连接各个分布的节点。这会用在广播状态的变化（例如配置变化）或者其他的消息指令。Spring Bus 的一个核心思想是通过分布式的启动器对 Spring Boot 应用进行扩展，也可以用来建立一个多个应用之间的通信频道。目前唯一实现的方式是用 Amqp 消息代理作为通道，同样特性的设置（有些取决于通道的设置）在更多通道的文档中。

Spring Cloud Bus 被国内很多都翻译为消息总线，也挺形象的。大家可以将它理解为管理和传播所有分布式项目中的消息既可，其实本质是利用了 MQ 的广播机制在分布式的系统中传播消息，目前常用的有 Kafka 和 RabbitMQ。利用 Bus 的机制可以做很多的事情，其中配置中心客户端刷新就是典型的应用场景之一，我们用一张图来描述 Bus 在配置中心使用的机制。

实战

我们选择上一篇文章 Spring Cloud（八）：配置中心（服务化与高可用） 版本的示例代码来改造, MQ 我们使用 RabbitMQ 来做示例。

因为用的是 Spring Boot 2.0.1 + Spring Cloud Finchley.RC1，更新较多，坑也比较多，这里就把代码再贴一遍了。

示例代码：GitHub

服务端

POM 配置

在 pom.xml 里添加，这 4 个是必须的

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<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-config-server</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-bus</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-stream-binder-rabbit</artifactId>
</dependency>

配置文件

application.yml 内容如下

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spring:
  application:
    name: config-server
  cloud:
    config:
      server:
        git:
          uri: https://github.com/zhaoyibo/spring-cloud-study
          search-paths: config-repo
    bus:
      enabled: true
      trace:
        enabled: true
server:
  port: 12000
eureka:
  client:
    service-url:
      defaultZone: http://localhost:7000/eureka/
management:
  endpoints:
    web:
      exposure:
        include: bus-refresh

启动类

加@EnableConfigServer注解

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@SpringBootApplication
@EnableConfigServer
public class ConfigServerApplication {

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

客户端

POM 配置

在 pom.xml 里添加以下依赖，前 5 个是必须的，最后一个 webflux 你可以用 web 来代替

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<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-config</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-bus</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-stream-binder-rabbit</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

这里容易漏掉spring-boot-starter-actuator，如果缺了这个，当对服务端执行/actuator/bus-refresh的时候，客户端接收不到信息，Console 里只会显示以下信息（我就是在这儿被困了好久……）

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2018-04-19 18:50:05.711  INFO 39762 --- [vOu-GI8c8mJtQ-1] o.s.a.r.c.CachingConnectionFactory       : Attempting to connect to: [localhost:5672]
2018-04-19 18:50:05.739  INFO 39762 --- [vOu-GI8c8mJtQ-1] o.s.a.r.c.CachingConnectionFactory       : Created new connection: rabbitConnectionFactory.publisher#2bc15b3b:[email protected] [delegate=amqp:[email protected]:5672/, localPort= 60107]
2018-04-19 18:50:05.749  INFO 39762 --- [vOu-GI8c8mJtQ-1] o.s.amqp.rabbit.core.RabbitAdmin         : Auto-declaring a non-durable, auto-delete, or exclusive Queue (springCloudBus.anonymous.bOoVqQuSQvOu-GI8c8mJtQ) durable:false, auto-delete:true, exclusive:true. It will be redeclared if the broker stops and is restarted while the connection factory is alive, but all messages will be lost.

配置文件

还是分为两个，分别如下
application.yml

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spring:
  application:
    name: config-client
  cloud:
    bus:
      trace:
        enabled: true
      enabled: true
server:
  port: 13000

bootstrap.yml

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spring:
  cloud:
    config:
      name: config-client
      profile: dev
      label: master
      discovery:
        enabled: true
        service-id: config-server
eureka:
  client:
    service-url:
      defaultZone: http://localhost:7000/eureka/

Controller

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@RestController
@RefreshScope
public class HelloController {

    @Value("${info.profile:error}")
    private String profile;

    @GetMapping("/info")
    public Mono<String> hello() {
        return Mono.justOrEmpty(profile);
    }

}

@RefreshScope必须加，否则客户端会受到服务端的更新消息，但是更新不了，因为不知道更新哪里的。

至于启动主类，用默认生成的不用改，就不贴了。

测试

分别启动 eureka、config-server 和两个 config-client

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## 打包
./mvnw clean package -Dmaven.test.skip=true

## 运行两个 client
java -jar target/spring-cloud-config-client-0.0.1-SNAPSHOT.jar --server.port=13000
java -jar target/spring-cloud-config-client-0.0.1-SNAPSHOT.jar --server.port=13001

启动后，RabbitMQ 中会自动创建一个 topic 类型的 Exchange 和两个以springCloudBus.anonymous.开头的匿名 Queue

我们访问 http://localhost:13000/info 和 http://localhost:13001/info 返回内容的都是dev。
将 Git 中的配置信息由dev改为dev bus，并执行

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curl -X POST http://localhost:12000/actuator/bus-refresh/

再次访问 http://localhost:13000/info 和 http://localhost:13001/info 这时返回内容就是修改之后的dev bus了，说明成功了。

服务端在刷新接口产生的的日志：

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2018-04-19 18:37:08.034  INFO 38109 --- [io-12000-exec-9] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:37:08 CST 2018]; root of context hierarchy
2018-04-19 18:37:08.148  INFO 38109 --- [io-12000-exec-9] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2018-04-19 18:37:08.163  INFO 38109 --- [io-12000-exec-9] trationDelegate$BeanPostProcessorChecker : Bean 'configurationPropertiesRebinderAutoConfiguration' of type [org.springframework.cloud.autoconfigure.ConfigurationPropertiesRebinderAutoConfiguration$$EnhancerBySpringCGLIB$$32744ef0] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-04-19 18:37:08.294  INFO 38109 --- [io-12000-exec-9] o.s.boot.SpringApplication               : No active profile set, falling back to default profiles: default
2018-04-19 18:37:08.301  INFO 38109 --- [io-12000-exec-9] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:37:08 CST 2018]; parent: org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]
2018-04-19 18:37:08.306  INFO 38109 --- [io-12000-exec-9] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2018-04-19 18:37:08.330  INFO 38109 --- [io-12000-exec-9] o.s.boot.SpringApplication               : Started application in 0.391 seconds (JVM running for 511.143)
2018-04-19 18:37:08.333  INFO 38109 --- [io-12000-exec-9] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:37:08 CST 2018]; parent: org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]
2018-04-19 18:37:08.334  INFO 38109 --- [io-12000-exec-9] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:37:08 CST 2018]; root of context hierarchy
2018-04-19 18:37:08.985  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Shutting down DiscoveryClient ...
2018-04-19 18:37:09.007  INFO 38109 --- [io-12000-exec-9] o.s.c.n.eureka.InstanceInfoFactory       : Setting initial instance status as: STARTING
2018-04-19 18:37:12.012  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Unregistering ...
2018-04-19 18:37:12.019  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_CONFIG-SERVER/172.16.106.93:config-server:12000 - deregister  status: 200
2018-04-19 18:37:12.030  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Completed shut down of DiscoveryClient
2018-04-19 18:37:12.032  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Initializing Eureka in region us-east-1
2018-04-19 18:37:12.037  INFO 38109 --- [io-12000-exec-9] c.n.d.provider.DiscoveryJerseyProvider   : Using JSON encoding codec LegacyJacksonJson
2018-04-19 18:37:12.037  INFO 38109 --- [io-12000-exec-9] c.n.d.provider.DiscoveryJerseyProvider   : Using JSON decoding codec LegacyJacksonJson
2018-04-19 18:37:12.037  INFO 38109 --- [io-12000-exec-9] c.n.d.provider.DiscoveryJerseyProvider   : Using XML encoding codec XStreamXml
2018-04-19 18:37:12.037  INFO 38109 --- [io-12000-exec-9] c.n.d.provider.DiscoveryJerseyProvider   : Using XML decoding codec XStreamXml
2018-04-19 18:37:12.145  INFO 38109 --- [io-12000-exec-9] c.n.d.s.r.aws.ConfigClusterResolver      : Resolving eureka endpoints via configuration
2018-04-19 18:37:12.146  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Disable delta property : false
2018-04-19 18:37:12.146  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Single vip registry refresh property : null
2018-04-19 18:37:12.146  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Force full registry fetch : false
2018-04-19 18:37:12.146  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Application is null : false
2018-04-19 18:37:12.146  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Registered Applications size is zero : true
2018-04-19 18:37:12.146  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Application version is -1: true
2018-04-19 18:37:12.146  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Getting all instance registry info from the eureka server
2018-04-19 18:37:12.151  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : The response status is 200
2018-04-19 18:37:12.152  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Starting heartbeat executor: renew interval is: 30
2018-04-19 18:37:12.152  INFO 38109 --- [io-12000-exec-9] c.n.discovery.InstanceInfoReplicator     : InstanceInfoReplicator onDemand update allowed rate per min is 4
2018-04-19 18:37:12.153  INFO 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Discovery Client initialized at timestamp 1524134232153 with initial instances count: 3
2018-04-19 18:37:12.154  INFO 38109 --- [io-12000-exec-9] o.s.c.n.e.s.EurekaServiceRegistry        : Unregistering application config-server with eureka with status DOWN
2018-04-19 18:37:12.154  INFO 38109 --- [io-12000-exec-9] o.s.c.n.e.s.EurekaServiceRegistry        : Registering application config-server with eureka with status UP
2018-04-19 18:37:12.154  WARN 38109 --- [io-12000-exec-9] com.netflix.discovery.DiscoveryClient    : Saw local status change event StatusChangeEvent [timestamp=1524134232154, current=UP, previous=DOWN]
2018-04-19 18:37:12.155  INFO 38109 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_CONFIG-SERVER/172.16.106.93:config-server:12000: registering service...
2018-04-19 18:37:12.155  INFO 38109 --- [io-12000-exec-9] o.s.cloud.bus.event.RefreshListener      : Received remote refresh request. Keys refreshed []
2018-04-19 18:37:12.165  INFO 38109 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_CONFIG-SERVER/172.16.106.93:config-server:12000 - registration status: 204
2018-04-19 18:37:14.044  INFO 38109 --- [o-12000-exec-10] .c.s.e.MultipleJGitEnvironmentRepository : Fetched for remote master and found 1 updates
2018-04-19 18:37:14.105  INFO 38109 --- [o-12000-exec-10] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:37:14 CST 2018]; root of context hierarchy
2018-04-19 18:37:14.108  INFO 38109 --- [o-12000-exec-10] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2018-04-19 18:37:14.112  INFO 38109 --- [o-12000-exec-10] o.s.c.c.s.e.NativeEnvironmentRepository  : Adding property source: file:/var/folders/rm/v0glpzzn7dxd1nj5nk00ssq00000gn/T/config-repo-520847716419946533/config-repo/config-client-dev.yml
2018-04-19 18:37:14.112  INFO 38109 --- [o-12000-exec-10] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:37:14 CST 2018]; root of context hierarchy
2018-04-19 18:37:15.386  INFO 38109 --- [io-12000-exec-1] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:37:15 CST 2018]; root of context hierarchy
2018-04-19 18:37:15.388  INFO 38109 --- [io-12000-exec-1] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2018-04-19 18:37:15.393  INFO 38109 --- [io-12000-exec-1] o.s.c.c.s.e.NativeEnvironmentRepository  : Adding property source: file:/var/folders/rm/v0glpzzn7dxd1nj5nk00ssq00000gn/T/config-repo-520847716419946533/config-repo/config-client-dev.yml
2018-04-19 18:37:15.393  INFO 38109 --- [io-12000-exec-1] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:37:15 CST 2018]; root of context hierarchy

客户端在刷新接口产生的的日志：

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2018-04-19 18:35:45.899  INFO 38808 --- [x6SsSoOn6XStg-1] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:35:45 CST 2018]; root of context hierarchy
2018-04-19 18:35:46.292  INFO 38808 --- [x6SsSoOn6XStg-1] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2018-04-19 18:35:46.448  INFO 38808 --- [x6SsSoOn6XStg-1] trationDelegate$BeanPostProcessorChecker : Bean 'configurationPropertiesRebinderAutoConfiguration' of type [org.springframework.cloud.autoconfigure.ConfigurationPropertiesRebinderAutoConfiguration$$EnhancerBySpringCGLIB$$494fdb28] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-04-19 18:35:46.778  INFO 38808 --- [x6SsSoOn6XStg-1] o.s.c.n.eureka.InstanceInfoFactory       : Setting initial instance status as: STARTING
2018-04-19 18:35:46.819  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Initializing Eureka in region us-east-1
2018-04-19 18:35:46.828  INFO 38808 --- [x6SsSoOn6XStg-1] c.n.d.provider.DiscoveryJerseyProvider   : Using JSON encoding codec LegacyJacksonJson
2018-04-19 18:35:46.828  INFO 38808 --- [x6SsSoOn6XStg-1] c.n.d.provider.DiscoveryJerseyProvider   : Using JSON decoding codec LegacyJacksonJson
2018-04-19 18:35:46.828  INFO 38808 --- [x6SsSoOn6XStg-1] c.n.d.provider.DiscoveryJerseyProvider   : Using XML encoding codec XStreamXml
2018-04-19 18:35:46.829  INFO 38808 --- [x6SsSoOn6XStg-1] c.n.d.provider.DiscoveryJerseyProvider   : Using XML decoding codec XStreamXml
2018-04-19 18:35:47.017  INFO 38808 --- [x6SsSoOn6XStg-1] c.n.d.s.r.aws.ConfigClusterResolver      : Resolving eureka endpoints via configuration
2018-04-19 18:35:47.019  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Disable delta property : false
2018-04-19 18:35:47.019  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Single vip registry refresh property : null
2018-04-19 18:35:47.019  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Force full registry fetch : false
2018-04-19 18:35:47.019  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Application is null : false
2018-04-19 18:35:47.019  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Registered Applications size is zero : true
2018-04-19 18:35:47.019  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Application version is -1: true
2018-04-19 18:35:47.019  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Getting all instance registry info from the eureka server
2018-04-19 18:35:47.031  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : The response status is 200
2018-04-19 18:35:47.034  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Not registering with Eureka server per configuration
2018-04-19 18:35:47.035  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Discovery Client initialized at timestamp 1524134147035 with initial instances count: 3
2018-04-19 18:35:47.287  INFO 38808 --- [x6SsSoOn6XStg-1] c.c.c.ConfigServicePropertySourceLocator : Fetching config from server at: http://172.16.106.93:12000/
2018-04-19 18:35:51.550  INFO 38808 --- [x6SsSoOn6XStg-1] c.c.c.ConfigServicePropertySourceLocator : Located environment: name=config-client, profiles=[dev], label=master, version=77913e8aed0054fd05fe6889db20baf96e781632, state=null
2018-04-19 18:35:51.550  INFO 38808 --- [x6SsSoOn6XStg-1] b.c.PropertySourceBootstrapConfiguration : Located property source: CompositePropertySource {name='configService', propertySources=[MapPropertySource {name='configClient'}, MapPropertySource {name='https://github.com/zhaoyibo/spring-cloud-study/config-repo/config-client-dev.yml'}]}
2018-04-19 18:35:51.553  INFO 38808 --- [x6SsSoOn6XStg-1] o.s.boot.SpringApplication               : No active profile set, falling back to default profiles: default
2018-04-19 18:35:51.557  INFO 38808 --- [x6SsSoOn6XStg-1] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:35:51 CST 2018]; parent: org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]
2018-04-19 18:35:51.569  INFO 38808 --- [x6SsSoOn6XStg-1] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2018-04-19 18:35:51.626  INFO 38808 --- [x6SsSoOn6XStg-1] o.s.boot.SpringApplication               : Started application in 6.011 seconds (JVM running for 312.876)
2018-04-19 18:35:51.627  INFO 38808 --- [x6SsSoOn6XStg-1] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:35:51 CST 2018]; parent: org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]
2018-04-19 18:35:51.630  INFO 38808 --- [x6SsSoOn6XStg-1] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicatio[email protected]: startup date [Thu Apr 19 18:35:45 CST 2018]; root of context hierarchy
2018-04-19 18:35:51.630  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Shutting down DiscoveryClient ...
2018-04-19 18:35:51.641  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Completed shut down of DiscoveryClient
2018-04-19 18:35:51.839  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Shutting down DiscoveryClient ...
2018-04-19 18:35:51.840  INFO 38808 --- [x6SsSoOn6XStg-1] o.s.c.n.eureka.InstanceInfoFactory       : Setting initial instance status as: STARTING
2018-04-19 18:35:54.848  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Unregistering ...
2018-04-19 18:35:54.854  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_CONFIG-CLIENT/172.16.106.93:config-client:13001 - deregister  status: 200
2018-04-19 18:35:54.863  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Completed shut down of DiscoveryClient
2018-04-19 18:35:54.865  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Initializing Eureka in region us-east-1
2018-04-19 18:35:54.867  INFO 38808 --- [x6SsSoOn6XStg-1] c.n.d.provider.DiscoveryJerseyProvider   : Using JSON encoding codec LegacyJacksonJson
2018-04-19 18:35:54.867  INFO 38808 --- [x6SsSoOn6XStg-1] c.n.d.provider.DiscoveryJerseyProvider   : Using JSON decoding codec LegacyJacksonJson
2018-04-19 18:35:54.867  INFO 38808 --- [x6SsSoOn6XStg-1] c.n.d.provider.DiscoveryJerseyProvider   : Using XML encoding codec XStreamXml
2018-04-19 18:35:54.867  INFO 38808 --- [x6SsSoOn6XStg-1] c.n.d.provider.DiscoveryJerseyProvider   : Using XML decoding codec XStreamXml
2018-04-19 18:35:54.937  INFO 38808 --- [x6SsSoOn6XStg-1] c.n.d.s.r.aws.ConfigClusterResolver      : Resolving eureka endpoints via configuration
2018-04-19 18:35:54.938  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Disable delta property : false
2018-04-19 18:35:54.938  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Single vip registry refresh property : null
2018-04-19 18:35:54.938  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Force full registry fetch : false
2018-04-19 18:35:54.938  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Application is null : false
2018-04-19 18:35:54.938  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Registered Applications size is zero : true
2018-04-19 18:35:54.939  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Application version is -1: true
2018-04-19 18:35:54.939  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Getting all instance registry info from the eureka server
2018-04-19 18:35:54.949  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : The response status is 200
2018-04-19 18:35:54.951  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Starting heartbeat executor: renew interval is: 30
2018-04-19 18:35:54.952  INFO 38808 --- [x6SsSoOn6XStg-1] c.n.discovery.InstanceInfoReplicator     : InstanceInfoReplicator onDemand update allowed rate per min is 4
2018-04-19 18:35:54.953  INFO 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Discovery Client initialized at timestamp 1524134154953 with initial instances count: 3
2018-04-19 18:35:54.954  INFO 38808 --- [x6SsSoOn6XStg-1] o.s.c.n.e.s.EurekaServiceRegistry        : Unregistering application config-client with eureka with status DOWN
2018-04-19 18:35:54.975  INFO 38808 --- [x6SsSoOn6XStg-1] o.s.c.n.e.s.EurekaServiceRegistry        : Registering application config-client with eureka with status UP
2018-04-19 18:35:54.977  WARN 38808 --- [x6SsSoOn6XStg-1] com.netflix.discovery.DiscoveryClient    : Saw local status change event StatusChangeEvent [timestamp=1524134154977, current=UP, previous=DOWN]
2018-04-19 18:35:54.980  INFO 38808 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_CONFIG-CLIENT/172.16.106.93:config-client:13001: registering service...
2018-04-19 18:35:54.986  INFO 38808 --- [x6SsSoOn6XStg-1] o.s.cloud.bus.event.RefreshListener      : Received remote refresh request. Keys refreshed [config.client.version, info.profile]
2018-04-19 18:35:54.999  INFO 38808 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_CONFIG-CLIENT/172.16.106.93:config-client:13001 - registration status: 204

思考

这里我们再想一个问题：如果对客户端使用 /actuator/bus-refresh会发生什么呢？是只刷新了当前客户端还是刷新全部客户端，还是一个都没刷新呢？

不如来试一下吧：

首先我们需要把客户端上的bus-refresh端点给放出来

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management:
  endpoints:
    web:
      exposure:
        include: bus-refresh

重启客户端，这时候访问 http://localhost:13000/info 和 http://localhost:13001/info 返回的都是dev bus。

去 Git 里把配置信息由dev bus改为dev，然后执行

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curl -X POST http://localhost:13000/actuator/bus-refresh/

再次访问 http://localhost:13000/info 和 http://localhost:13001/info 发现这时返回的都是dev了，说明只要开启 Spring Cloud Bus 后，不管是对 config-server 还是 config-client 执行/actuator/bus-refresh都是可以更新配置的。

其它

因为版本问题，以下两部分还未在该版本进行验证。待有时间了试一下。

局部刷新

某些场景下（例如灰度发布），我们可能只想刷新部分微服务的配置，此时可通过/actuator/bus-refresh/{destination}端点的 destination 参数来定位要刷新的应用程序。

例如：/actuator/bus-refresh/customers:8000，这样消息总线上的微服务实例就会根据 destination 参数的值来判断是否需要要刷新。其中，customers:8000指的是各个微服务的 ApplicationContext ID。

destination 参数也可以用来定位特定的微服务。例如：/actuator/bus-refresh/customers:**，这样就可以触发 customers 微服务所有实例的配置刷新。

跟踪总线事件

一些场景下，我们可能希望知道 Spring Cloud Bus 事件传播的细节。此时，我们可以跟踪总线事件（RemoteApplicationEvent 的子类都是总线事件）。

跟踪总线事件非常简单，只需设置spring.cloud.bus.trace.enabled=true，这样在/actuator/bus-refresh端点被请求后，访问 /trace （现在好像是/actuator/httptrace）端点就可获得 类似如下的结果 ：

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{
  "timestamp": 1495851419032,
  "info": {
    "signal": "spring.cloud.bus.ack",
    "type": "RefreshRemoteApplicationEvent",
    "id": "c4d374b7-58ea-4928-a312-31984def293b",
    "origin": "stores:8002",
    "destination": "*:**"
  }
  },
  {
  "timestamp": 1495851419033,
  "info": {
    "signal": "spring.cloud.bus.sent",
    "type": "RefreshRemoteApplicationEvent",
    "id": "c4d374b7-58ea-4928-a312-31984def293b",
    "origin": "spring-cloud-config-client:8001",
    "destination": "*:**"
  }
  },
  {
  "timestamp": 1495851422175,
  "info": {
    "signal": "spring.cloud.bus.ack",
    "type": "RefreshRemoteApplicationEvent",
    "id": "c4d374b7-58ea-4928-a312-31984def293b",
    "origin": "customers:8001",
    "destination": "*:**"
  }
}

这个日志显示了customers:8001发出了 RefreshRemoteApplicationEvent 事件，广播给所有的服务，被customers:9000和stores:8081接受到了。想要对接受到的消息自定义自己的处理方式的话，可以添加@EventListener注解的 AckRemoteApplicationEvent 和 SentApplicationEvent 类型到你自己的应用中。或者到 TraceRepository 类中，直接处理数据。

这样，我们就可清晰地知道事件的传播细节。

相关阅读

Spring Cloud（一）：服务治理技术概览
Spring Cloud（二）：服务注册与发现 Eureka
Spring Cloud（三）：服务提供与调用 Eureka
Spring Cloud（四）：服务容错保护 Hystrix
Spring Cloud（五）：Hystrix 监控面板
Spring Cloud（六）：Hystrix 监控数据聚合 Turbine
Spring Cloud（七）：配置中心（Git 版与动态刷新）
Spring Cloud（八）：配置中心（服务化与高可用）
Spring Cloud（九）：配置中心（消息总线）
Spring Cloud（十）：服务网关 Zuul（路由）
Spring Cloud（十一）：服务网关 Zuul（过滤器）
Spring Cloud（十二）：分布式链路跟踪（Sleuth 与 Zipkin）

示例代码：GitHub

参考

springcloud(九)：配置中心和消息总线（配置中心终结版）
Spring Cloud - Push Notifications and Spring Cloud Bus
Refreshable Configuration using Spring Cloud Config Server, Spring Cloud Bus, RabbitMQ and Git
springboot 2.0.0.RELEASE +spring cloud Finchley.M7 +springcloud bus+kafka 实现配置动态刷新
Config Server——使用 Spring Cloud Bus 自动刷新配置

更多内容请访问：IT源点

注意：本文归作者所有，未经作者允许，不得转载

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