Previous implementations of Spring Cloud Config typically required clients to specify the server's URL directly using spring.cloud.config.uri. This approach becomes problematic when scaling the server into a cluster, as changes to the server's IP address or load-balancing setup necessitate manual updates to every client. To align with the service governance principles of Spring Cloud, the configuration server should be registered as a service within a service registry like Eureka. Cleints can then dynamically discover the configuration server via service discovery rather than hardcoded URLs.

Server-Side Modifications

1. Add Eureka Client Dependency

Include the Eureka client starter in the configuration server's build file (e.g., pom.xml).

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

2. Configure Eureka Registration

Update application.properties to point the service to the Eureka registry and define the application name.

spring.application.name=config-center-service
eureka.client.serviceUrl.defaultZone=http://localhost:8088/eureka/

3. Enable Service Discovery

Annotate the main application class with @EnableDiscoveryClient to allow the config server to register itself.

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

Client-Side Modifications

1. Add Eureka Client Dependency

Similar to the server, the client application must also include the Eureka client dependency to participate in service discovery.

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

2. Update Client Configuration

Modify bootstrap.properties (or bootstrap.yml) to disable the direct URI lookup and enable service discovery. The client will now look for a service registered under the name defined in spring.cloud.config.discovery.serviceId.

spring.application.name=config-client-app
spring.cloud.config.name=app-settings
spring.cloud.config.profile=dev
spring.cloud.config.label=master

# Enable Config Service Discovery
spring.cloud.config.discovery.enabled=true
spring.cloud.config.discovery.serviceId=config-center-service

# Eureka Registry Location
eureka.client.serviceUrl.defaultZone=http://localhost:8088/eureka/

• spring.cloud.config.discovery.enabled: Activates the service discovery feature for the config client.
• spring.cloud.config.discovery.serviceId: The name of the configuration server as registered in Eureka.

3. Enable Discovery on Client

Ensure the client's main class is also annotated with @EnableDiscoveryClient.

Verification

1. Start the Eureka Server application.
2. Start the modified Config Server (Config Center).
3. Start the Client Application.
4. Navigate to the Eureka dashboard (e.g., http://localhost:8088/) to confirm both the config server and client are registered.
5. Access the client endpoint (e.g., http://localhost:8002/hello) to verify that properties are being loaded dynamically from the config server via Eureka.