The most easies Spring Cloud Tutorial ever | Chapter 6: Distributed Configuration Center (Spring Cloud Config) (Finchley Version)

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Backend Developers

4 min readMay 3, 2022

When I talked about zuul in the previous article, I already mentioned that the configuration service is used to save the configuration files of each service. It is Spring Cloud Config.

Introduction

In a distributed system, due to the huge number of services, in order to facilitate unified management and real-time update of service configuration files, a distributed configuration center component is required. In Spring Cloud, there is a distributed configuration center component spring cloud config, which supports the configuration service to be placed in the memory of the configuration service (ie local), and also in the remote Git repository. In the spring cloud config component, there are two roles, one is config server and the other is config client.

2. Build Config Server

The parent maven project is omitted, the parent pom file:

<?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><groupId>com.forezp</groupId>
    <artifactId>sc-f-chapter6</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>pom</packaging><modules>
        <module>config-server</module>
        <module>config-client</module>
    </modules><name>sc-f-chapter6</name>
    <description>Demo project for Spring Boot</description><parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.3.RELEASE</version>
        <relativePath/>
    </parent><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.RELEASE</spring-cloud.version>
    </properties><dependencies>
        <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>

Create a spring-boot project named config-server, and its pom.xml is as follows:

<?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><groupId>com.forezp</groupId>
 <artifactId>config-server</artifactId>
 <version>0.0.1-SNAPSHOT</version>
 <packaging>jar</packaging><name>config-server</name>
 <description>Demo project for Spring Boot</description><parent>
  <groupId>com.forezp</groupId>
  <artifactId>sc-f-chapter6</artifactId>
  <version>0.0.1-SNAPSHOT</version>
 </parent><dependencies>
  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-config-server</artifactId>
  </dependency>
 </dependencies>
 <build>
  <plugins>
   <plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
   </plugin>
  </plugins>
 </build></project>

Add the @EnableConfigServer annotation to the entry Application class of the program to enable the function of configuring the server. The code is as follows:

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

You need to configure the following in the program’s configuration file application.properties file:

spring.application.name=config-server
server.port=8888spring.cloud.config.server.git.uri=https://github.com/forezp/SpringcloudConfig/
spring.cloud.config.server.git.searchPaths=respo
spring.cloud.config.label=master
spring.cloud.config.server.git.username=
spring.cloud.config.server.git.password=

spring.cloud.config.server.git.uri: configure the git repository address
spring.cloud.config.server.git.searchPaths: configure repository paths
spring.cloud.config.label: configure the branch of the repository
spring.cloud.config.server.git.username: username for accessing the git repository
spring.cloud.config.server.git.password: User password to access the git repository

If the Git repository is a public repository, you do not need to fill in the user name and password. If it is a private repository, it needs to be filled in. This example is a public repository, so you can use it with confidence.

There is a file config-client-dev.properties in the remote warehouse https://github.com/forezp/SpringcloudConfig/ There is a property in the file:

foo = foo version 3

Start the program: visit http://localhost:8888/foo/dev

{"name":"foo","profiles":["dev"],"label":"master",
"version":"792ffc77c03f4b138d28e89b576900ac5e01a44b","state":null,"propertySources":[]}

Prove that the configuration service center can obtain configuration information from a remote program.

The mapping between http request addresses and resource files is as follows:

/{application}/{profile}[/{label}]
/{application}-{profile}.yml
/{label}/{application}-{profile}.yml
/{application}-{profile}.properties
/{label}/{application}-{profile}.properties

3. Build a config client

Recreate a springboot project, name it config-client, and its pom file:

<?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><groupId>com.forezp</groupId>
 <artifactId>config-client</artifactId>
 <version>0.0.1-SNAPSHOT</version>
 <packaging>jar</packaging><name>config-client</name>
 <description>Demo project for Spring Boot</description><parent>
  <groupId>com.forezp</groupId>
  <artifactId>sc-f-chapter6</artifactId>
  <version>0.0.1-SNAPSHOT</version>
 </parent><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>
 </dependencies><build>
  <plugins>
   <plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
   </plugin>
  </plugins>
 </build></project>

It’s configuration file bootstrap.properties:

spring.application.name=config-client
spring.cloud.config.label=master
spring.cloud.config.profile=dev
spring.cloud.config.uri= http://localhost:8888/
server.port=8881

spring.cloud.config.label specifies the branch of the remote repository
spring.cloud.config.profile

1.dev development environment configuration file

2.test test environment

3.pro formal environment

spring.cloud.config.uri= http://localhost:8888/ Specifies the URL of the configuration service center.

The entry class of the program, write an API interface “/hi”, and return the value of the foo variable read from the configuration center. The code is as follows:

@SpringBootApplication
@RestController
public class ConfigClientApplication {public static void main(String[] args) {
  SpringApplication.run(ConfigClientApplication.class, args);
 }@Value("${foo}")
 String foo;
 @RequestMapping(value = "/hi")
 public String hi(){
  return foo;
 }
}

Open the URL to visit: http://localhost:8881/hi, the webpage displays:

foo version 3

This means that config-client gets the properties of foo from config-server, and config-server reads it from the git repository, as shown in the figure:

The most easies Spring Cloud Tutorial ever | Chapter 6: Distributed Configuration Center (Spring Cloud Config) (Finchley Version)

Written by Keith