Serverless App Engine:Use Spring Cloud to develop microservice applications and deploy them to SAE

Why use the SAE service registry

The SAE service registry provides a commercial version of the open source Nacos Server. Applications developed with the open source Spring Cloud Alibaba Nacos Discovery can directly use the commercial service registry provided by SAE.

The SAE service registry offers several advantages over self-managed registries, such as Nacos, Eureka, and Consul:

• Shared components. You do not need to deploy or maintain Nacos, Eureka, or Consul. This reduces costs.

• Encrypted links. Service registration and discovery calls are encrypted to protect your services from being discovered by unauthorized applications.

• The SAE service registry is seamlessly integrated with other SAE components, offering a comprehensive microservice solution that includes environment isolation and phased release.

When you deploy an application on SAE, the SAE service registry automatically sets the Nacos Server address, service port, namespace, AccessKey, and Context-path. These settings take precedence, and no additional configuration is required.

Preparations

• Download Maven and set the environment variable.

• Start Nacos Server.

  1. Download and decompress the Nacos Server package.

  2. Go to the nacos/bin directory and start Nacos Server.

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

     • Windows: Run the startup.cmd -m standalone command.

     Note

     standalone indicates that the startup.cmd file is run in standalone mode, not cluster mode. By default, the startup.cmd file is started in cluster mode. If you double-click the startup.cmd file to run the file in a Windows system, the startup fails. In this case, you must configure MODE="standalone" in the startup.cmd file. For more information, see Quick Start for Nacos.

Step 1: Create a service provider

Create a service provider application project in your local environment. Add dependencies, enable service registration and discovery, and specify Nacos Server as the service registry.

1. Create a Maven project named nacos-service-provider.

2. Add dependencies to the pom.xml file.

   For a specific example, see nacos-service-provider. This topic uses Spring Boot 2.1.4.RELEASE and Spring Cloud Greenwich.SR1, with the following dependencies:

   Note

   Spring Boot 2.4 and later are not supported. Spring Cloud Alibaba 2.2.6.RELEASE (client version 1.4.2) is supported.

   <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>2.1.0.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>                  

   This example uses Spring Cloud Greenwich. The corresponding version of Spring Cloud Alibaba is 2.1.1.RELEASE.

   • If you use Spring Cloud Finchley, the corresponding version of Spring Cloud Alibaba is 2.0.1.RELEASE.

   • If you use Spring Cloud Edgware, the corresponding version of Spring Cloud Alibaba is 1.5.1.RELEASE.

     Note

     Spring Cloud Edgware has reached the end of its lifecycle. We recommend that you do not use this version to develop applications.

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

4. In the package com.aliware.edas, create a startup class named ProviderApplication for the service provider and add the following code.

   The @EnableDiscoveryClient annotation enables service registration and discovery for this application.

       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);
           }
       }             

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

   In EchoController, specify the URL mapping as /echo/{string}, set the HTTP method to GET, retrieve the method parameter from the URL path, and return the received parameter.

       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;
           }
       }              

6. Create a file application.properties in the src\main\resources path. In application.properties, add the following configuration to specify the Nacos Server address.

       spring.application.name=service-provider
       server.port=18081
       spring.cloud.nacos.discovery.server-addr=127.0.0.1:8848               

   In this example, 127.0.0.1 is the address of the Nacos Server. If your Nacos Server is deployed on a different machine, you must change this to the corresponding IP address. If you have other requirements, you can add configurations to the application.properties file. For more information, see Configuration items.

7. Verify the results.

   1. Run the main function of ProviderApplication in nacos-service-provider to start the application.

   2. Log on to the local Nacos Server console at http://127.0.0.1:8848/nacos.

      The default username and password for the local Nacos console are both nacos.

   3. In the navigation pane on the left, choose Service Management > Service List.

      The service list now includes service-provider, and you can view the details of this service by clicking Details.

Step 2: Create a service consumer

This section describes how to create a service consumer that uses Nacos for service discovery and calls the provider using RestTemplate and FeignClient.

1. Create a Maven project named nacos-service-consumer.

2. Add dependencies to the pom.xml file.

   For a specific example, see nacos-service-consumer.

   <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>2.1.0.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>        

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

4. Configure RestTemplate and FeignClient in the package com.aliware.edas.

   1. In the package com.aliware.edas, create an interface named EchoService, add the @FeignClient annotation, and configure the corresponding HTTP URL and method.

      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. In the package com.aliware.edas, create a startup class named ConsumerApplication and add the necessary configuration.

      • To enable service registration and discovery, use the @EnableDiscoveryClient annotation.

      • Use the @EnableFeignClients annotation to activate FeignClient.

      • Integrate RestTemplate with service discovery by adding the @LoadBalanced annotation.

      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);
          }
      }

5. In the package com.aliware.edas, create the class TestController to demonstrate and verify the service discovery feature.

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

6. In the src\main\resources path, create a file named application.properties. In the application.properties file, add the following configuration to specify the address of the Nacos Server.

       spring.application.name=service-consumer
       server.port=18082
       spring.cloud.nacos.discovery.server-addr=127.0.0.1:8848

   In this example, 127.0.0.1 is the address of the Nacos Server. If your Nacos Server is deployed on a different machine, you must change the value to the IP address of that machine. If you have other requirements, you can add configurations to the application.properties file. For more information, see Configuration items.

7. Verify the results.

   1. Run the main function of the ConsumerApplication class in the nacos-service-consumer project to start the application.

   2. Log on to the local Nacos Server console at http://127.0.0.1:8848/nacos.

      The default username and password for the local Nacos console are both nacos.

   3. In the navigation pane on the left, choose Service Management > Service List. The service list now includes service-consumer, and you can view the details of this service by clicking Details.

Step 3: Local testing

Test the service calls from the consumer to the provider in the local environment.

• For Linux, Unix, and macOS: run the following commands.

  curl http://127.0.0.1:18082/echo-rest/rest-rest
  curl http://127.0.0.1:18082/echo-feign/feign-rest

• For Windows: enter http://127.0.0.1:18082/echo-rest/rest-rest and http://127.0.0.1:18082/echo-feign/feign-rest in your browser.

Step 4: Deploy the application to SAE

When you deploy an application to SAE, the SAE service registry automatically sets the Nacos Server address, service port, namespace, AccessKey, and Context-path information with high priority. You do not need to make any additional configurations. You can retain or delete the original configurations.

Step 5: Verify the results

1. Bind a public-facing CLB to the nacos-service-consumer application deployed on SAE. When you configure public access for the CLB, select HTTP for Network Protocol, set HTTP Port to 80, and set Container Port to 18082. For more information, see Bind a CLB to an application.

2. In the address bar of a browser, enter the public IP address of the application in the http://<Public IP address>/echo-rest/rest-rest or http://<Public IP address>/echo-feign/feign-rest format and press Enter. If a response is returned on the page, the application is deployed successfully.

Configuration items

For more information about Spring Cloud Alibaba Nacos Discovery, see Nacos Discovery.