Microservices Engine:Register Spring Cloud applications with MSE Nacos registries

1.1 Create the Maven project

Create a Maven project named nacos-service-provider.

1.2 Add dependencies

Add the following to the pom.xml file:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.4.RELEASE</version>
    <relativePath/>
</parent>

<dependencies>
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        <version>2.1.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </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>

1.3 Create the boot class and controller

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

In the com.aliware.edas package, create the boot class ProviderApplication. The @EnableDiscoveryClient annotation activates service registration and discovery with the configured Nacos server.

package com.aliware.edas;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class ProviderApplication {

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

In the same package, create a controller class named EchoController. This controller exposes a GET /echo/{string} endpoint that returns the path variable.

package com.aliware.edas;

import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class EchoController {
    @RequestMapping(value = "/echo/{string}", method = RequestMethod.GET)
    public String echo(@PathVariable String string) {
        return string;
    }
}

1.4 Configure the Nacos server endpoint

Under src/main/resources, create application.properties with the following content:

spring.application.name=service-provider
server.port=18081
spring.cloud.nacos.discovery.server-addr=<your-nacos-endpoint>:8848

Replace <your-nacos-endpoint> with your MSE Nacos public endpoint. Find this value on the Instances page of the MSE console. The endpoint follows the format mse.XX.nacos.mse.aliyuncs.com.

To use a custom namespace instead of the default Public namespace, add:

spring.cloud.nacos.discovery.namespace=<namespace-id>

1.5 Verify provider registration

1. Run the main method of ProviderApplication in the nacos-service-provider project to start the provider.

2. Log on to the MSE console.

3. Select a region in the top navigation bar.

4. In the left-side navigation pane, choose Microservices Registry > Instances, then click the instance name.

5. Choose Service Management > Services.

6. Confirm that service-provider appears in the service list.

2.1 Create the Maven project

Create a Maven project named nacos-service-consumer.

2.2 Add dependencies

Add the following to the pom.xml file. Compared to the provider, the consumer adds spring-cloud-starter-openfeign for declarative HTTP client support.

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.4.RELEASE</version>
    <relativePath/>
</parent>

<dependencies>
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        <version>2.1.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-openfeign</artifactId>
    </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>

2.3 Create the Feign client interface

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

In the com.aliware.edas package, create an interface named EchoService. The @FeignClient annotation declares this as a Feign client that targets the service-provider service by name. Nacos resolves the service name to an available instance automatically.

package com.aliware.edas;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@FeignClient(name = "service-provider")
public interface EchoService {
    @RequestMapping(value = "/echo/{str}", method = RequestMethod.GET)
    String echo(@PathVariable("str") String str);
}

2.4 Create the boot class

In the com.aliware.edas package, create the boot class ConsumerApplication with the following annotations:

package com.aliware.edas;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class ConsumerApplication {

    @LoadBalanced
    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

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

2.5 Create the test controller

In the com.aliware.edas package, create a controller named TestController that exposes two endpoints -- one using RestTemplate and one using FeignClient -- to demonstrate both service discovery approaches.

package com.aliware.edas;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class TestController {

    @Autowired
    private RestTemplate restTemplate;
    @Autowired
    private EchoService echoService;

    // Calls the provider using RestTemplate with service discovery
    @RequestMapping(value = "/echo-rest/{str}", method = RequestMethod.GET)
    public String rest(@PathVariable String str) {
        return restTemplate.getForObject("http://service-provider/echo/" + str,
                String.class);
    }

    // Calls the provider using FeignClient
    @RequestMapping(value = "/echo-feign/{str}", method = RequestMethod.GET)
    public String feign(@PathVariable String str) {
        return echoService.echo(str);
    }
}

2.6 Configure the Nacos server endpoint

Under src/main/resources, create application.properties with the following content:

spring.application.name=service-consumer
server.port=18082
spring.cloud.nacos.discovery.server-addr=<your-nacos-endpoint>:8848

Replace <your-nacos-endpoint> with the same MSE Nacos public endpoint used for the provider.

To use a custom namespace, add:

spring.cloud.nacos.discovery.namespace=<namespace-id>

2.7 Verify consumer registration

1. Run the main method of ConsumerApplication in the nacos-service-consumer project to start the consumer.

2. Log on to the MSE console.

3. Select a region in the top navigation bar.

4. In the left-side navigation pane, choose Microservices Registry > Instances, then click the instance name.

5. Choose Service Management > Services.

6. Confirm that service-consumer appears in the service list.

Services do not appear in the MSE console after startup

This typically happens when the application runs in an on-premises environment and the MSE Nacos registry has not been configured to allow inbound connections from your network.

Configure a public IP address whitelist to grant access. By default, the whitelist is set to 127.0.0.1/32, which blocks all external connections. For instructions, see Configure a public IP address whitelist.