Dynamic Configuration of Spring Cloud Microservices with Spring Cloud Alibaba Nacos

1. Traditional Configuration Method

Define configuration items directly in application.properties and inject them using @Value in a controller, then expose an endpoint to return the values. This approach requires restarting services when configuration changes.

member.nickname = "悟空聊架构"
member.age = "18"

@Value("${member.nickname}")
private String nickname;

@Value("$member.age")
private Integer age;

@RequestMapping("/test-local-config")
public R testLocalConfig() {
    return R.ok().put("nickname", nickname).put("age", age);
}

Result: values are read from the local file, but any change requires a service restart.

2. Introduce Nacos Dependency

Add the Spring Cloud Alibaba Nacos Config starter to the pom.xml of the common module.

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
</dependency>

3. Configure Nacos Metadata

Create bootstrap.properties with higher priority than other configuration files.

spring.application.name=passjava-member
spring.cloud.nacos.config.server-addr=127.0.0.1:8848

4. Add Configuration in Nacos Console

Data ID: passjava-member.properties Group: DEFAULT_GROUP Content:

member.nick="悟空"
member.age=10

5. Enable Dynamic Refresh

Annotate the controller with @RefreshScope so that changes in Nacos are automatically reloaded without restarting the service.

@RefreshScope
@RestController
@RequestMapping("member/sample")
public class SampleController { }

Log output shows the refreshed key member.age and the listener com.alibaba.cloud.nacos.refresh.NacosContextRefresher.

6. Namespace Management

Create separate namespaces for each microservice (e.g., passjava-member, passjava-channel, etc.) and configure the namespace in bootstrap.properties:

spring.cloud.nacos.config.namespace=passjava-member

After modifying the configuration in the corresponding namespace and restarting the service, the endpoint returns the updated values.

7. Group (Environment) Segmentation

Use groups to distinguish environments such as dev, test, and prod. Set the active group in bootstrap.properties: spring.cloud.nacos.config.group=prod Fetching the endpoint now returns the configuration from the prod group.

8. Multiple Configuration Sets

Split large configuration files (e.g., datasource, MyBatis‑Plus) into separate Data IDs and load them via extension-configs:

spring.cloud.nacos.config.extension-configs[0].data-id=datasource.yml
spring.cloud.nacos.config.extension-configs[0].group=dev
spring.cloud.nacos.config.extension-configs[0].refresh=true

spring.cloud.nacos.config.extension-configs[1].data-id=mybatis.yml
spring.cloud.nacos.config.extension-configs[1].group=dev
spring.cloud.nacos.config.extension-configs[1].refresh=true

spring.cloud.nacos.config.extension-configs[2].data-id=more.yml
spring.cloud.nacos.config.extension-configs[2].group=dev
spring.cloud.nacos.config.extension-configs[2].refresh=true

Testing shows that both the simple properties and the external YAML configurations are correctly applied.

9. Summary of Nacos Usage

Introduce Nacos dependency.

Configure Nacos server address and namespace.

Create Data IDs and groups for different environments.

Enable dynamic refresh with @RefreshScope.

Inject values using @Value.

Namespace isolates configuration per microservice.

Group separates configurations per environment.

Extension configs allow multiple configuration files.

10. Code Repository

All source code is available at https://github.com/Jackson0714/PassJava-Platform .