Manage application configurations

Start Nacos Server

1. Download and extract the Nacos Server package.

2. Go to the nacos/bin directory and run the startup command for your OS:

   • Linux, Unix, or macOS: sudo sh startup.sh -m standalone

   • Windows: startup.cmd -m standalone

   The -m standalone flag starts Nacos in standalone mode instead of cluster mode (the default). On Windows, double-clicking startup.cmd starts it in cluster mode and fails. To fix this, open the file and set MODE="standalone". See Quick Start for Nacos for details.

Create a configuration in local Nacos Server

1. Log in to the Nacos Server console. The default username and password are both nacos.

2. In the left navigation pane, click Configurations. On the Configurations page, click the icon in the upper-right corner.

3. On the Create configuration page, set the following parameters and click Publish:

   • Data ID: nacos-config-example.properties

   • Group: DEFAULT_GROUP

   • Configuration Content: test.name=nacos-config-test

Version compatibility

This example uses Spring Boot 2.1.4.RELEASE and Spring Cloud Greenwich.SR1. Choose the Spring Cloud Alibaba version that matches your Spring Cloud release:

Build the application

1. Create a Maven project named nacos-config-example.

2. Add the following dependencies to pom.xml. This example uses Spring Cloud Greenwich, so spring-cloud-starter-alibaba-nacos-config is version 2.1.1.RELEASE.

   <parent>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-parent</artifactId>
       <version>2.1.4.RELEASE</version>
       <relativePath/>
   </parent>
   
   <dependencies>
       <dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-web</artifactId>
       </dependency>
       <dependency>
           <groupId>com.alibaba.cloud</groupId>
           <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
           <version>2.1.1.RELEASE</version>
       </dependency>
   </dependencies>
   
   <dependencyManagement>
       <dependencies>
           <dependency>
               <groupId>org.springframework.cloud</groupId>
               <artifactId>spring-cloud-dependencies</artifactId>
               <version>Greenwich.SR1</version>
               <type>pom</type>
               <scope>import</scope>
           </dependency>
       </dependencies>
   </dependencyManagement>
   
   <build>
       <plugins>
           <plugin>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-maven-plugin</artifactId>
           </plugin>
       </plugins>
   </build>

3. In src/main/java, create the com.aliware.edas package.

4. In the com.aliware.edas package, create the NacosConfigExampleApplication startup class:

   import org.springframework.boot.SpringApplication;
   import org.springframework.boot.autoconfigure.SpringBootApplication;
   
   @SpringBootApplication
   public class NacosConfigExampleApplication {
       public static void main(String[] args) {
           SpringApplication.run(NacosConfigExampleApplication.class, args);
       }
   }

5. In the com.aliware.edas package, create the EchoController controller:

   • @Value("${test.name}") injects the value of the test.name key from Nacos Config.

   • @RefreshScope causes the bean to be re-created when Nacos pushes a configuration change, so the injected value updates automatically without a restart. Without this annotation, the application reads the configuration only at startup and ignores subsequent changes.

   import org.springframework.beans.factory.annotation.Value;
   import org.springframework.cloud.context.config.annotation.RefreshScope;
   import org.springframework.web.bind.annotation.RequestMapping;
   import org.springframework.web.bind.annotation.RestController;
   
   @RestController
   @RefreshScope
   public class EchoController {
   
       @Value("${test.name}")
       private String userName;
   
       @RequestMapping(value = "/")
       public String echo() {
           return userName;
       }
   }

6. In src/main/resources, create bootstrap.properties and add the following configuration to connect the application to your local Nacos Server. 127.0.0.1:8848 is the default Nacos Server address; 18081 is the application's service port. Change the address and port if your Nacos Server runs elsewhere.

   spring.application.name=nacos-config-example
   server.port=18081
   spring.cloud.nacos.config.server-addr=127.0.0.1:8848

   For all available configuration options, see Configuration reference.

7. Run the main method in NacosConfigExampleApplication to start the application locally.