Master Nacos Config Management in Spring Cloud: A Step‑by‑Step Guide

Introduction

Nacos not only provides service registration and discovery but also integrates a configuration center, allowing all configuration of a micro‑service architecture to be stored centrally. The advantages include isolated multi‑environment configurations with finer permission control, higher security, and the ability to package an application once and run it in multiple places, aligning with the "12 factors" of cloud‑native applications.

Quick Start

1. Create a Configuration in Nacos

Open the Nacos console, go to the configuration list, click the "+" button, and fill in the following fields:

DataId : alibaba-nacos-config-client.properties Group : DEFAULT_GROUP (default)

Configuration Format : Properties Configuration Content :

didispace.title=spring-cloud-alibaba-learning

2. Create the Spring Boot Application

Step 1 : Create a new Spring Boot project named alibaba-nacos-config-client.

Step 2 : Add the following dependencies to pom.xml (only the relevant parts are shown):

<parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>2.0.5.RELEASE</version>
</parent>

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-dependencies</artifactId>
      <version>Finchley.SR1</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-alibaba-dependencies</artifactId>
      <version>0.2.1.RELEASE</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
  </dependency>
  <dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.2</version>
    <optional>true</optional>
  </dependency>
</dependencies>

3. Implement the Application Main Class and Controller

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

    @Slf4j
    @RestController
    @RefreshScope
    static class TestController {
        @Value("${didispace.title:}")
        private String title;

        @GetMapping("/test")
        public String hello() {
            return title;
        }
    }
}

4. Create bootstrap.properties

Configure the application name and Nacos address:

spring.application.name=alibaba-nacos-config-client
server.port=8001
spring.cloud.nacos.config.server-addr=127.0.0.1:8848

Note : The bootstrap.properties file must be used, and the spring.application.name value must match the DataId created in Nacos (excluding the .properties suffix).

5. Run the Application

Start the Spring Boot application. The startup logs will show the DataId and Group that Nacos will load, e.g.:

INFO  NacosPropertySourceBuilder: Loading nacos data, dataId:'alibaba-nacos-config-client.properties', group:'DEFAULT_GROUP'

6. Verify Configuration Retrieval and Dynamic Refresh

Call the HTTP endpoint http://localhost:8001/test (using curl, Postman, etc.). The response will be the value of didispace.title from Nacos. Then modify the same key in the Nacos console and publish the change. The next request returns the updated value without restarting the application, thanks to the @RefreshScope annotation.

INFO  RefreshEventListener: Refresh keys changed:[didispace.title]

This demonstrates that the configuration is refreshed dynamically in the running client.

Reference

Nacos official documentation: https://nacos.io/zh-cn/docs/what-is-nacos.html

Code Repository

GitHub: https://github.com/dyc87112/SpringCloud-Learning/

Gitee: https://gitee.com/didispace/SpringCloud-Learning/