Using Nacos as Registration Center for Automatic Service Discovery

This example demonstrates how to use Nacos as a registration center to achieve automatic service discovery.

This example demonstrates Nacos as a registration center for automatic service discovery, based on a Spring Boot application. You can view the complete sample code here.

1 Basic Configuration

1.1 Add Dependency

Add the dependencies for dubbo and nacos-client:

<dependencies>
    <dependency>
        <groupId>org.apache.dubbo</groupId>
        <artifactId>dubbo</artifactId>
        <version>3.3.0</version>
    </dependency>
    <dependency>
      <groupId>com.alibaba.nacos</groupId>
      <artifactId>nacos-client</artifactId>
      <version>2.1.0</version>
    </dependency>
</dependencies>

For Spring Boot applications, you can use the following spring-boot-starter:

<dependency>
    <groupId>org.apache.dubbo</groupId>
    <artifactId>dubbo-spring-boot-starter</artifactId>
    <version>3.3.0</version>
</dependency>
<dependency>
    <groupId>org.apache.dubbo</groupId>
    <artifactId>dubbo-nacos-spring-boot-starter</artifactId>
    <version>3.3.0</version>
</dependency>

1.2 Nacos Version

Nacos version mapping:

1.3 Configure and Enable Nacos

# application.yml (Spring Boot)
dubbo
 registry
   address: nacos://localhost:8848
   register-mode: instance # New users should set this value, indicating the enablement of application-level service discovery. Options: interface, instance, all. Default is all; future versions will change default to instance.

or

# dubbo.properties
dubbo.registry.address=nacos://localhost:8848
dubbo.registry.register-mode=instance

or

<dubbo:registry address="nacos://localhost:8848" register-mode="instance"/>

2 Advanced Configuration

2.1 Authentication

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

or

# dubbo.properties
dubbo.registry.address: nacos://nacos:nacos@localhost:8848
dubbo.registry.register-mode=instance

2.2 Custom Namespace

# application.yml (Spring Boot)
dubbo:
 registry:
   address: nacos://localhost:8848?namespace=5cbb70a5-xxx-xxx-xxx-d43479ae0932
   register-mode: instance # New users should set this value, indicating the enablement of application-level service discovery. Options: interface, instance, all

or

# application.yml (Spring Boot)
dubbo:
 registry:
   address: nacos://localhost:8848
   register-mode: instance # New users should set this value, indicating the enablement of application-level service discovery. Options: interface, instance, all
   parameters.namespace: 5cbb70a5-xxx-xxx-xxx-d43479ae0932

2.3 Custom Group

# application.yml
dubbo:
 registry:
   address: nacos://localhost:8848
   register-mode: instance # New users should set this value, indicating the enablement of application-level service discovery. Options: interface, instance, all
   group: dubbo

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

2.4 Register Interface-Level Consumer

Since Dubbo version 3.0.0, a parameter has been added to indicate whether to register consumers. If you need to register consumers in the Nacos registration center, set the parameter (register-consumer-url) to true; the default is false.

# application.yml
dubbo:
  registry:
    register-mode: instance # New users should set this value, indicating the enablement of application-level service discovery. Options: interface, instance, all
    address: nacos://localhost:8848?register-consumer-url=true

or

# application.yml
dubbo:
  registry:
    address: nacos://localhost:8848
    register-mode: instance # New users should set this value, indicating the enablement of application-level service discovery. Options: interface, instance, all
    parameters.register-consumer-url: true

2.5 More Configuration

In nacos-server@1.0.0, clients can report instances with specific metadata to control instance behavior.

These parameters can be configured in Nacos similarly to namespace, such as

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

3 Working Principle

In the previous section, we explained the difference between application-level service discovery and interface-level service discovery. Below are the specific storage structures for both modes in Nacos.

3.1 Dubbo2 Registration Data

Then restart your Dubbo application. The service provision and consumption information of Dubbo can be displayed in the Nacos console:

As shown, the service prefix providers: contains metadata for service providers, while consumers: represents metadata for service consumers. Click on “Details” to view service status details:

3.2 Dubbo3 Registration Data

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

Dubbo3 adopts a “dual registration model” of “application-level service discovery + interface-level service discovery” by default, so you will find both application-level service (application name) and interface-level service (interface name) appearing in the Nacos console. You can change the registration behavior by configuring dubbo.registry.register-mode=instance/interface/all.

3.3 Client Cache

3.4 Heartbeat Detection

3.5

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Last modified September 30, 2024: Update & Translate Overview Docs (#3040) (d37ebceaea7)