Spring Boot Config Client Example

This tutorial shows how to create a Spring Boot Config Client that will its read application configuration from a Spring Boot Config Server that externally keeps the application configuration wtih local & dev profiles.

To configure a Config Server locally, view this page

https://www.techblogss.com/microservices/spring-cloud-config-server

Step 1) Create pom.xml for config client project

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>2.1.6.RELEASE</version>
        </dependency>
    </dependencies>
</dependencyManagement>
 
<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-config</artifactId>
        <version>2.1.6.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</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-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>
    
<repositories>
    <repository>
        <id>central-repo</id>
        <name>Central Repository</name>
        <url>https://repo1.maven.org/maven2</url>
    </repository>
</repositories>

Step 2) Create ConfigClient class that will launch config client, AppConfiguration class that holds configuration & MessageRestController

package com.example.demo;

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

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

package com.example.demo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;

@RefreshScope
public class AppConfiguration {

    @Value("${message:Hello default}")
    private String message;

    String getMessage() {
        return this.message;
    }

}

package com.example.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MessageRestController {
	
    @Autowired
    private AppConfiguration configuration; 
	
    @RequestMapping("/message")
    String getMessage() {
        return configuration.getMessage();
    }

}

Step 3) Create application.properties, bootstrap.yml, bootstrap-local.yml, bootstrap-dev.yml files and keep in src/main/resources folder

application.properties

management.endpoints.web.exposure.include=*

bootstrap.yml (to load the configuration from config server.)

spring:
  application:
    name: config-server

bootstrap-local.yml

spring:
  cloud:
    config:
     uri: http://localhost:8888
          
logging:
  file: C:/Users/bisht/configuration-server.log
  level:
    ROOT: 'INFO'

bootstrap-dev.yml

spring:
  cloud:
    config:
     uri: http://localhost:8888
          
logging:
  file: C:/Users/bisht/configuration-server.log
  level:
    ROOT: 'INFO'

Step 4) Launch ConfigClient application using dev/local profile

To Run this Spring Boot application using dev profile, use following command →
java -Dspring.profiles.active=dev -jar demo-0.0.1-SNAPSHOT.jar

To Run this Spring Boot application using local profile, use following command →
java -Dspring.profiles.active=local -jar demo-0.0.1-SNAPSHOT.jar

Step 5) Validating Config Client

Open any browser and launch http://localhost:8080/message. You will see below details displayed for dev & local profiles in the broswer.

Maven Build

Step 6) Updating and refreshing configuration.

Now update application-local.properties in config server and run below command to refresh the properties in client config. Observe the property that was updated without restarting config-server or config-client application.

C:\Users\bisht>curl -X POST http://localhost:8080/actuator/refresh -d {} -H "Content-Type: application/json"
["config.client.version","message"]