Nacos

1 precondition

• Understand Dubbo basic development steps
• Install and start Nacos service

When Dubbo uses 3.0.0 and above, it needs to use Nacos 2.0.0 and above.

2 Instructions for use

Check here full sample code

2.1 Add dependencies

<dependencies>
    <dependency>
        <groupId>org.apache.dubbo</groupId>
        <artifactId>dubbo</artifactId>
        <version>3.0.9</version>
    </dependency>
    <dependency>
      <groupId>com.alibaba.nacos</groupId>
      <artifactId>nacos-client</artifactId>
      <version>2.1.0</version>
    </dependency>
     <!-- Introduce Dubbo Nacos extension, or you can add Nacos dependency directly as shown above-->
     <!--
        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo-registry-nacos</artifactId>
            <version>3.0.9</version>
        </dependency>
     -->
</dependencies>

Add Dubbo and Nacos dependencies

Dubbo 3.0.0 and above require nacos-client 2.0.0 and above

2.2 Configure and enable Nacos

# application.yml (Spring Boot)
dubbo
 registry
   address: nacos://localhost:8848

or

# dubbo.properties
dubbo.registry.address=nacos://localhost:8848

or

<dubbo:registry address="nacos://localhost:8848" />

To enable the app, see what it looks like after registration or how it works, see [How it works](#4-How it works).

3 Advanced configuration

3.1 Authentication

# application.yml (Spring Boot)
dubbo
 registry
   address: nacos://localhost:8848?username=nacos&password=nacos

or

# dubbo.properties
dubbo.registry.address: nacos://nacos:nacos@localhost:8848

3.2 Custom namespace

# application.yml (Spring Boot)
dubbo:
 registry:
   address: nacos://localhost:8848?namespace=5cbb70a5-xxx-xxx-xxx-d43479ae0932

or

# application.yml (Spring Boot)
dubbo:
 registry:
   address: nacos://localhost:8848
   parameters.namespace: 5cbb70a5-xxx-xxx-xxx-d43479ae0932

3.3 Custom grouping

# application.yml
dubbo:
 registry:
   address: nacos://localhost:8848
   group: dubbo

If not configured, the group is specified by Nacos by default. Group and namespace represent different isolation levels in Nacos. Generally speaking, namespace is used to isolate different users or environments, and group is used to further group data in the same environment.

3.4 Register interface-level consumers

After Dubbo3.0.0, the parameter of whether to register consumers is added. If you need to register consumers to the nacos registration center, you need to set the parameter (register-consumer-url) to true, and the default is false.

# application.yml
dubbo:
  registry:
    address: nacos://localhost:8848?register-consumer-url=true

or

# application.yml
dubbo:
  registry:
    address: nacos://localhost:8848
    parameters.register-consumer-url: true
    

3.5 More configurations

After the nacos-server@1.0.0 version, the client is supported to control some behaviors of the instance by reporting some instances containing specific metadata to the server.

These parameters can be configured to Nacos through parameter expansion in a manner similar to namespace, such as

dubbo.registry.parameters.preserved.heart.beat.timeout=5000

4 How it works

The following is just to show the working principle of Nacos as the Dubbo registration center. It is recommended to use Dubbo Admin for Dubbo service operation and maintenance

4.1 Dubbo2 registration data

Then, restart your Dubbo application, and Dubbo’s service provision and consumption information can be displayed in the Nacos console:

As shown in the figure, the service name prefixed with providers: is the meta information of the service provider, and consumers: represents the meta information of the service consumer. Click “Details” to view the service status details:

4.2 Dubbo3 registration data

The “service name” for application-level service discovery is the application name

Dubbo3 adopts the dual registration mode of “application-level service discovery + interface-level service discovery” by default, so you will find that application-level services (application names) and interface-level services (interface names) appear in the Nacos console at the same time, you can configure dubbo .registry.register-mode=instance/interface/all to change the registration behavior.