Spring Cloud Config

Spring Cloud Config

1. Spring Boot Overview

Spring Boot is a framework that simplifies creating production-ready Spring applications. Key points:

  • Provides embedded servers (Tomcat, Jetty), so you don’t need to deploy WAR files.
  • Auto-configuration reduces boilerplate code.
  • Supports microservices architecture.

2. Spring Cloud Config Overview

Spring Cloud Config provides centralized configuration management for distributed systems. It allows you to:

  • Store configuration in Git, SVN, or filesystem.
  • Support dynamic refresh of configuration without restarting services.
  • Separate configuration from code, making microservices easier to maintain.

Components:

  1. Config Server – exposes configuration to clients.
  2. Config Client – Spring Boot application that fetches config from the server.

3. Example Setup

We’ll create:

  1. Config Server (Spring Boot app)
  2. Config Client (Spring Boot app)

Step 1: Config Server

pom.xml dependencies:

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-config-server</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>

Application class:

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

application.yml:

server:
  port: 8888

spring:
  cloud:
    config:
      server:
        git:
          uri: https://github.com/yourusername/config-repo
          clone-on-start: true

Here, config-repo is a Git repository containing config files like application.yml.

Step 2: Config Client

pom.xml dependencies:

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-config</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>

application.yml:

spring:
  application:
    name: client-app
  cloud:
    config:
      uri: http://localhost:8888

Controller example:

@RestController
public class DemoController {

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

    @GetMapping("/message")
    public String getMessage() {
        return message;
    }
}

Step 3: Git Config Repository Example

In your Git repo, create a file client-app.yml:

message: "Hello from Config Server!"

When the client app runs and you access http://localhost:8080/message, it should return:

Hello from Config Server!

✅ How it Works

  1. Config Client starts → fetches config from Config Server.
  2. Config Server reads configuration from Git repository.
  3. Client uses configuration values at runtime.

Leave a Reply