Understanding the Spring Cloud Config Starter

Spring Cloud Config provides server-side and client-side support for externalized configuration in a distributed system. With the Config Server, you have a central place to manage external properties for applications across all environments. This blog post will guide you through setting up and using the spring-cloud-config starter with practical examples.

Understanding the Spring Cloud Config Starter

Why Use Spring Cloud Config?

In a microservices architecture, managing configuration across multiple services can be challenging. Spring Cloud Config addresses this by providing a centralized configuration service that is easy to manage and scale. Here are some key benefits:

• Centralized Management: Store all configurations in a central repository.
• Dynamic Updates: Update configurations without restarting your applications.
• Environment-Specific Configurations: Manage different configurations for different environments (development, testing, production).

Setting Up Spring Cloud Config Server

To get started, you need to set up a Config Server. This server will serve the configuration properties to your client applications.

1. Add Dependencies

   First, add the necessary dependencies to your pom.xml:

   <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>
   

2. Enable Config Server

   Create a Spring Boot application and enable the Config Server by adding the @EnableConfigServer annotation:

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

3. Configure Application Properties

   In your application.properties or application.yml, configure the server to use a Git repository for storing configurations:

   server.port=8888
   spring.cloud.config.server.git.uri=https://github.com/your-repo/config-repo
   

Setting Up Spring Cloud Config Client

Next, set up a client application that will fetch configurations from the Config Server.

1. Add Dependencies

   Add the following dependencies to your client’s pom.xml:

   <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>
   

2. Configure Application Properties

   In your client’s bootstrap.properties or bootstrap.yml, specify the Config Server URL:

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

3. Access Configuration Properties

   You can now access the configuration properties in your Spring application using the @Value annotation or Environment object:

   @RestController
   public class MessageController {
   
       @Value("${message:Hello default}")
       private String message;
   
       @GetMapping("/message")
       public String getMessage() {
           return this.message;
       }
   }
   

Example Configuration Repository

Create a Git repository (e.g., config-repo) and add configuration files for your applications. For example, create a file named my-client-app.properties with the following content:

message=Hello from Spring Cloud Config

Running the Applications

1. Start the Config Server:

   mvn spring-boot:run -Dspring-boot.run.profiles=config-server
   

2. Start the Client Application:

   mvn spring-boot:run -Dspring-boot.run.profiles=client
   

3. Access the Configuration:

   Open your browser and navigate to http://localhost:8080/message. You should see the message from the Config Server.

Conclusion

Spring Cloud Config simplifies the management of configuration in a microservices architecture by providing a centralized configuration service. By following the steps outlined in this blog post, you can set up a Config Server and client applications to dynamically manage configurations across different environments.

Feel free to leave your comments or questions below. Happy coding!

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Keywords: Spring Cloud Config, Spring Boot, Microservices, Centralized Configuration, Dynamic Configuration, Spring Cloud Starter

¹: Baeldung - Quick Intro to Spring Cloud Configuration ²: Spring Cloud Config Documentation ³: Spring Cloud Config Quick Start