在微服务SpringCloud之Spring Cloud Config配置中心SVN博客中每个client刷新配置信息时需要post请求/actuator/refresh,但客户端越来越多时,,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。
一、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。
二、启动RabbitMq
启动RabbitMq的具体方法之前博客已经写了,略过。
三、SpringCloud Config Server端
1.引入依赖
Demo是在上篇博客的基础上进行修改,主要增加引入spring-cloud-starter-bus-amqp。
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xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0modelVersion> <parent> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-parentartifactId> <version>2.1.6.RELEASEversion> <relativePath/> parent> <groupId>com.examplegroupId> <artifactId>SpringCloudConfigServerartifactId> <version>0.0.1-SNAPSHOTversion> <packaging>warpackaging> <name>SpringCloudConfigServername> <description>Demo project for Spring Bootdescription> <properties> <java.version>1.8java.version> <spring-cloud.version>Greenwich.SR2spring-cloud.version> properties> <dependencies> <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-webartifactId> dependency> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-config-serverartifactId> dependency> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId> dependency> <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-tomcatartifactId> <scope>providedscope> dependency> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-starter-bus-amqpartifactId> dependency> <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-testartifactId> <scope>testscope> dependency> dependencies> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-dependenciesartifactId> <version>${spring-cloud.version}version> <type>pomtype> <scope>importscope> dependency> dependencies> dependencyManagement> <build> <plugins> <plugin> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-maven-pluginartifactId> plugin> plugins> build> project>
2.新增RabbitMq配置信息
这里主要增加开启消息跟踪、配置rabbitmq相关信息。
spring.cloud.bus.trace.enabled=true
spring.rabbitmq.host=127.0.0.1
spring.rabbitmq.port=5672
spring.rabbitmq.username=guest
spring.rabbitmq.password=guest
management.endpoints.web.exposure.include=*
四、SpringCloud Config Client端
1.引入依赖
Client端和服务端有类似的配置,也是引入spring-cloud-starter-bus-amqp,增加rabbitmq相关配置。
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xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0modelVersion> <parent> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-parentartifactId> <version>2.1.6.RELEASEversion> <relativePath/> parent> <groupId>com.examplegroupId> <artifactId>SpringCloudConfigClientartifactId> <version>0.0.1-SNAPSHOTversion> <packaging>warpackaging> <name>SpringCloudConfigClientname> <description>Demo project for Spring Bootdescription> <properties> <java.version>1.8java.version> <spring-cloud.version>Greenwich.SR2spring-cloud.version> properties> <dependencies> <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-webartifactId> dependency> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-starter-configartifactId> dependency> <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-actuatorartifactId> dependency> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId> dependency> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-starter-bus-amqpartifactId> dependency> <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-tomcatartifactId> <scope>providedscope> dependency> <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-testartifactId> <scope>testscope> dependency> dependencies> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloudgroupId> <artifactId>spring-cloud-dependenciesartifactId> <version>${spring-cloud.version}version> <type>pomtype> <scope>importscope> dependency> dependencies> dependencyManagement> <build> <plugins> <plugin> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-maven-pluginartifactId> plugin> plugins> build> project>
2.新增RabbitMq配置信息
management.endpoints.web.exposure.include=*
## 开启消息跟踪
spring.cloud.bus.trace.enabled=true
spring.rabbitmq.host=127.0.0.1
spring.rabbitmq.port=5672
spring.rabbitmq.username=guest
spring.rabbitmq.password=guest
五、测试
1.依次启动EurekaServer、SpringCloudConfigServer、SpringCloudConfigClient,输入http://localhost:8001/neo-config/dev、http://localhost:8003/hello。
2.修改配置信息
修改github上的配置信息,再次输入上面的url,在8003端口的是没有更新的,此时需要post请求http://localhost:8001/actuator/bus-refresh来刷新SpringCloudConfigServer。这里在post请求时可能会出现405、404的错误,需要设置management.endpoints.web.exposure.include=*,并且由于springcloud的版本不同,post请求的url也不同。
post请求之后返回204,然后刷新即可看到最新的配置信息。
参考:http://www.ityouknow.com/springcloud/2017/05/26/springcloud-config-eureka-bus.html