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

SAE service registry

The SAE service registry provides Spring Cloud Alibaba Nacos Discovery that is the general availability (GA) version of the open source Nacos Server. You can use the GA version of the SAE service registry for applications that are developed based on Spring Cloud Alibaba Nacos Discovery.

Compared with Nacos, Eureka, and Consul, the SAE service registry provides the following advantages:

• Components are shared. This reduces the deployment, management, and maintenance costs of Nacos, Eureka, or Consul.
• Links are encrypted for calls during service registration and discovery. This protects your services from being discovered by unauthorized applications.
• The SAE service registry is integrated into other components of SAE to provide a complete set of microservice solutions, such as environment isolation and canary release.

When you deploy an application on SAE, the SAE service registry automatically specifies the following information at a higher priority: Nacos Server IP address, service port, namespace, AccessKey pair, and Context-path.

Preparations

• Download Maven and set the environment variables.
• 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 provider

Create a provider application project in an on-premises environment, add dependencies, enable service registration and discovery, and then specify the Nacos server as the service registry.

1. Create a Maven project named nacos-service-provider.
2. Add dependencies to the pom.xml file.

   For more information, see nacos-service-provider. The following sample code provides an example on how to add the Spring Boot 2.1.4.RELEASE and Spring Cloud Greenwich.SR1 dependencies:

   Note Spring Boot 2.4 or later is 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>                  

   In this example, Spring Cloud Greenwich is used. The version of Spring Cloud Alibaba for Spring Cloud Greenwich is 2.1.1.RELEASE.

   • The version of Spring Cloud Alibaba for Spring Cloud Finchley is 2.0.1.RELEASE.
   • If you use Spring Cloud Edgware, the Spring Cloud Alibaba version is 1.5.1.RELEASE.
     Note The Spring Cloud Edgware release reached the end of life (EOL). We recommend that you do not use this release to develop applications.
3. In src\main\java, create a package named com.aliware.edas.
4. In the com.aliware.edas package, create a startup class named ProviderApplication for the provider, and add the following sample code.

   The @EnableDiscoveryClient annotation is used to enable the service registration and discovery feature for the provider 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 com.aliware.edas package, create EchoController.

   In EchoController, specify /echo/{string} as the URL mapping and GET as the HTTP method. Obtain the method parameter from the URL path, and echo 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. In src\main\resources, create a file named application.properties and add the following configuration to application.properties to specify the IP address of Nacos Server.

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

   In the preceding configuration, 127.0.0.1 indicates the IP address of your Nacos Server. If your Nacos Server is deployed on another server, you must change the value to the IP address of the server. If you have other requirements, add the required configurations to the application.properties file. For more information, see Configuration items.

7. Verify the result.
   1. Execute the main function of ProviderApplication in the nacos-service-provider project to start the provider.
   2. Log on to the on-premises Nacos Server console at http://127.0.0.1:8848/nacos.
      The default username and password that can be used to log on to the Nacos Server console are nacos.
   3. In the left-side navigation pane, choose Service Management > Services.
      You can view that service-provider is displayed in the service list. You can also query the details of the service in Details.

Step 2: Create a consumer

This section describes the service registration feature, and how Nacos Server works with RestTemplate and FeignClient.

1. Create a Maven project named nacos-service-consumer.
2. Add dependencies to the pom.xml file.

   For more information, 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 src\main\java, create a package named com.aliware.edas.
4. In the com.aliware.edas package, configure RestTemplate and FeignClient.
   1. In the com.aliware.edas package, create an interface class named EchoService, add the @FeignClient annotation, and then specify the HTTP URL and HTTP 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 com.aliware.edas package, create a startup class named ConsumerApplication and add the related configurations.
      • Add the @EnableDiscoveryClient annotation to enable service registration and discovery.
      • Add the @EnableFeignClients annotation to enable FeignClient.
      • Add the @LoadBalanced annotation to integrate RestTemplate with service discovery.

      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 com.aliware.edas package, create a class named TestController to view 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 src\main\resources, create a file named application.properties and add the following configuration to application.properties to specify the IP address of Nacos Server.

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

   In the preceding configuration, 127.0.0.1 indicates the IP address of Nacos Server. If your Nacos Server is deployed on another server, you must change the value to the IP address of the server. If you have other requirements, add the required configurations in the application.properties file. For more information, see Configuration items.

7. Verify the result.
   1. Execute the main function of ConsumerApplication in the nacos-service-consumer project to start the consumer application.
   2. Log on to the on-premises Nacos Server console at http://127.0.0.1:8848/nacos.
      The default username and password that can be used to log on to the Nacos Server console are nacos.
   3. In the left-side navigation pane, choose Service Management > Services. You can view that service-consumer is displayed in the service list. You can also query the details of the service in Details.

Step 3: Test the result in an on-premises environment

Initiate a call from the consumer to the provider in an on-premises environment and test the result.

• On Linux, UNIX, or 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

• On Windows, enter http://127.0.0.1:18082/echo-rest/rest-rest and http://127.0.0.1:18082/echo-feign/feign-rest in the browser.

Step 4: Deploy the applications on SAE

When you deploy an application on SAE, the SAE service registry specifies the following information at a higher priority: Nacos server IP address, service port, namespace, AccessKey pair, and Context-path. You do not need to configure additional settings. You can retain or delete the original configurations.

Step 5: Verify the result

1. Bind a Server Load Balancer (SLB) instance to the application that is deployed on SAE. For more information, see Bind an Internet-facing SLB instance.
2. Enter the public endpoint in the address bar of your browser and initiate a call request on the homepage of the application.
3. View service call data in the SAE console.
   1. Log on to the SAE console.
   2. In the left-side navigation pane, click Applications. In the top navigation bar, select a region. Then, click the name of an application.
   3. In the left-side navigation pane of the Basic Information page of the consumer application, choose Application Monitoring > Application Overview to get an overview of the service call data.
   If call data is detected, the service call is successful.

Configuration items

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