Follow me SpringCloud | VII: Spring Cloud Config configuration center availability and refresh

SpringCloud series of tutorials | VII: Spring Cloud Config configuration center availability and refresh

Springboot: 2.1.6.RELEASE

SpringCloud: Greenwich.SR1

Unless otherwise specified, the full use of this tutorial series or later

1 Introduction

Previous We talked Spring Cloud Config configuration center, and Github to do and integration, our Server is a stand-alone end of any stand-alone version of the service can only use the test environment or do it yourself Demo test, the production environment is strictly prohibited stand-alone service , and distribution center is an important node in the whole micro-services system, especially automatic expansion in DevOps, if the distribution center downtime, then all automatic expansion will fail.

So we talk about this a high-availability configuration center, it comes highly available, in springcloud system, there is a registry, then our configuration center is a service, is it possible to do using the Eureka service registration and found it ?

The answer is yes.

2. Serve end

We will end on one of Serve Copy to a new directory, the increased reliance Eureka-client, making the Config-Serve can register on the Eureka.

2.1 pom.xml

<?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>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.springcloud</groupId>
    <artifactId>config-server</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>config-server</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR1</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-config-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

2.2 Profile application.yml

server:
  port: 8080
spring:
  application:
    name: spring-cloud-config-server
  cloud:
    config:
      server:
        git:
          uri: https://github.com/meteor1993/SpringCloudLearning
          search-paths: chapter6/springcloud-config
          username: username
          password: password
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/

Increase eureka address configuration

2.3 startup class

Increased support for the startup class @EnableEurekaClient activation registry

package com.springcloud.configserver;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.config.server.EnableConfigServer;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableConfigServer
@EnableEurekaClient
public class ConfigServerApplication {

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

}

Server-side so we registered the modifications are complete. First start Eureka, restart Serve, in your browser to http: // localhost: 8761 /, you can see the end of our Serve has been registered to the registry, and then we began to transform Client end.

3. Client-side

A first or upper end of Client Copy over, and Server side as increased reliance Eureka-client, making the Config-Client service can be found from the registry.

3.1 pom.xml

<?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>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.springcloud</groupId>
    <artifactId>config-client</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>config-client</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR1</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-config</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

3.2 bootstrap.properties

Here we need to empty application.yml, all configurations are all transferred to the bootstrap.properties.

spring.application.name=spring-cloud-config-client
server.port=8081

spring.cloud.config.name=springcloud-config
spring.cloud.config.profile=dev
spring.cloud.config.label=master
spring.cloud.config.discovery.enabled=true
spring.cloud.config.discovery.serviceId=spring-cloud-config-server

eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

Spring.cloud.config.uri mainly removed directly to the server side address configuration, increasing the final three configurations:

• spring.cloud.config.discovery.enabled: open Config service discovery support
• spring.cloud.config.discovery.serviceId: Specifies the server-side name, i.e. the value of the server-side spring.application.name
• eureka.client.serviceUrl.defaultZone: at the address registration center

3.3 startup class

Increased support for the startup class @EnableEurekaClient activation registry

package com.springcloud.configclient;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableEurekaClient
public class ConfigClientApplication {

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

}

4. High Availability

Now we have to simulate the production environment.

First, in turn start Eureka, Server, Client.

Start two config-serve in the idea, we modify the idea to configure the startup configuration, change to port 8000 start config-serve.

First visit http: // localhost: 8761 /, you can see two config-serve are properly registered to the registry.

Can be found as shown above will also provide two end service configuration server center, used to prevent the influence of the system goes down after a certain stage.

We visit the client side of the link: http: // localhost: 8081 / hello, you can see displayed correctly: hello dev update1, refresh a few times, showing no problem, and now we randomly stopped config-serve service port, and then to refresh the page, you can find that page still displays correctly: hello dev update1.

至此，我们高可用的目的已经达到，但是，不知道各位有没有映像，我们上一篇留了一个坑，服务启动后，我们修改远端github上的配置时，这个配置并不会实时被客户端端所获取到，下面我们来聊一聊有关Spring Cloud Config 刷新的问题。

5. refresh

我们的客户端并不能主动去感知Git或者Svn的配置变化，从而主动获取最新的配置。那么，客户端如何去主动获取新的配置信息呢？springcloud已经给我们提供了解决方案，每个客户端通过POST方法触发各自的/refresh。

修改config-client项目已到达可以refresh的功能。

5.1 添加依赖pom.xml

在我们原有的config-client项目的pom.xml的基础增加新的依赖

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

增加了spring-boot-starter-actuator包，spring-boot-starter-actuator是一套监控的功能，可以监控程序在运行时状态，其中就包括/refresh的功能。

5.2 开启更新机制

需要给加载变量的类上面加载@RefreshScope，在客户端执行/refresh的时候就会更新此类下面的变量值。

package com.springcloud.configclient.controller;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @Author: shiyao.wei
 * @Date: 2019/7/4 16:19
 * @Version: 1.0
 * @Desc:
 */
@RestController
@RefreshScope // 使用该注解的类，会在接到SpringCloud配置中心配置刷新的时候，自动将新的配置更新到该类对应的字段中。
public class HelloController {

    @Value("${springcloud.hello}")
    private String hello;

    @RequestMapping("/hello")
    public String from() {
        return this.hello;
    }
}

5.3 配置文件bootstrap.properties

spring.application.name=spring-cloud-config-client
server.port=8081

spring.cloud.config.name=springcloud-config
spring.cloud.config.profile=dev
spring.cloud.config.label=master
spring.cloud.config.discovery.enabled=true
spring.cloud.config.discovery.serviceId=spring-cloud-config-server

eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

management.security.enabled=false
management.endpoints.web.exposure.include=*

• management.security.enabled： springboot 1.5.X 以上默认开通了安全认证，所以需要添加这个配置
• management.endpoints.web.exposure.include： springboot 2.x 默认只开启了info、health的访问，*代表开启所有访问

5.4 测试

我们先访问客户端的测试连接：http://localhost:8081/hello， 这时，页面的显示是：hello dev update1，我们修改github上的信息，修改为：hello dev update，现在访问http://localhost:8081/hello，得到的信息还是：hello dev update1，现在我们刷新一下客户端，通过cmd命令行执行：curl -X POST http://localhost:8081/actuator/refresh，可以看到命令行上有显示：["springcloud.hello","config.client.version"]，意味着springcloud.hello这个配置已经刷新，这时，我们再去刷新一下页面，可以看到，页面上得到的信息已经变为了：hello dev update，这时我们refresh成功。

每次手动刷新客户端还是很麻烦，有没有什么办法只要提交代码就自动调用客户端来更新呢，github的webhook是一个好的办法。

6. webhook

WebHook是当某个事件发生时，通过发送http post请求的方式来通知信息接收方。Webhook来监测你在Github.com上的各种事件，最常见的莫过于push事件。如果你设置了一个监测push事件的Webhook，那么每当你的这个项目有了任何提交，这个Webhook都会被触发，这时Github就会发送一个HTTP POST请求到你配置好的地址。

如此一来，你就可以通过这种方式去自动完成一些重复性工作，比如，你可以用Webhook来自动触发一些持续集成（CI）工具的运作，比如Travis CI；又或者是通过 Webhook 去部署你的线上服务器。下图就是github上面的webhook配置。

• Payload URL： 触发后回调的URL
• Content type： 数据格式，两种一般使用json
• Secret： 用作给POST的body加密的字符串。采用HMAC算法
• events： 触发的事件列表

events事件类型	描述
push	仓库有push时触发。默认事件
create	当有分支或标签被创建时触发
delete	当有分支或标签被删除时触发

这样我们就可以利用hook的机制去触发客户端的更新，但是当客户端越来越多的时候hook支持的已经不够优雅，另外每次增加客户端都需要改动hook也是不现实的。其实Spring Cloud给了我们更好解决方案，我们在下一篇接着聊。

示例代码-Github