Spring Cloud Consul 实现服务注册与发现

1、前言

本文通过创建 provider-service、consumer-service 两个微服务，并通过 feign 接口调用来演示 Spring Cloud 整合 Consul。阅读本文需要前置知识：

• Spring Boot
• Spring Cloud
• Spring Cloud Feign

2、搭建 provider-service 服务

2.1、创建 maven 模块

创建provider项目，添加provider-service、provider-service-remote-api两个maven模块：

2.2、添加 spring boot、spring cloud 依赖

在父模块provider中添加spring boot、spring cloud依赖，spring cloud使用截止当前最新版本Hoxton.SR1，关联spring boot版本2.2.2.RELEASE

<properties>
    <java.version>1.8</java.version>
    <spring-cloud.version>Hoxton.SR1</spring-cloud.version>
</properties>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.2.2.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${spring-cloud.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

注意：spring boot和spring cloud之间有版本依赖关系，如果想用其他版本，请自行查询对应的依赖版本，否则可能由于不兼容服务起不来

2.3、provider-service-remote-api模块编写feign接口

maven模块provider-service-remote-api引入spring cloud feign

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>
</dependencies>

代码编写，新建IProviderRemoteService接口

@FeignClient(name = "provider-service")
public interface IProviderRemoteService {

    @RequestMapping(value = "hello", method = RequestMethod.GET)
    String hello();
}

2.4、provider-service模块编写接口实现

maven 依赖

<dependency>
    <groupId>com.example</groupId>
    <artifactId>provider-service-remote-api</artifactId>
    <version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

接口实现类ProviderRemoteService

@RestController
public class ProviderRemoteService implements IProviderRemoteService {

    @Override
    public String hello() {
        return "hello world!";
    }
}

2.5、集成spring cloud consul

引入spring cloud consul模块

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-consul-discovery</artifactId>
</dependency>

application.yml添加consul配置

server:
  port: 8080
spring:
  application:
    name: provider-service
  cloud:
    consul:
      host: 127.0.0.1
      port: 8500
      discovery:
        heartbeat:
          enabled: true

启动类添加@EnableDiscoveryClient注解，启用服务发现功能

@SpringBootApplication
@EnableDiscoveryClient
public class Application {

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

}

到此，provider-service服务已经全部搭建完毕，完整项目结构：

3、搭建 consumer-service 服务

3.1、创建 maven 模块

创建consumer项目，添加consumer-service，因为该服务不需要对外提供接口，所以无需consumer-service-remote-api模块：

3.2、consumer-service 编写接口调用 provider-service服务

引用provider-service-remote-api

<dependency>
    <groupId>com.example</groupId>
    <artifactId>provider-service-remote-api</artifactId>
    <version>0.0.1-SNAPSHOT</version>
</dependency>

编写测试接口，通过feign调用provider-service服务

@RestController
public class ConsumerController {

    @Autowired
    private IProviderRemoteService providerRemoteService;

    @RequestMapping(value = "/test")
    public String test() {
        return providerRemoteService.hello();
    }
}

3.3、集成 spring cloud consul

同provider-service服务一样，引入spring cloud consul模块

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-consul-discovery</artifactId>
</dependency>

application.yml添加consul配置

server:
  port: 9090
spring:
  application:
    name: consumer-service
  cloud:
    consul:
      host: 127.0.0.1
      port: 8500
      discovery:
        heartbeat:
          enabled: true

启动类添加@EnableDiscoveryClient注解，启用服务发现功能，并添加@EnableFeignClients注解，启用feign功能

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class Application {

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

}

到此，consumer-service服务也搭建完成，完整项目结构：

4、测试

4.1、启动 consul 服务

为了便于测试，笔者在本机以开发者模式起了一个consul服务

D:\consul>consul agent -dev
==> Starting Consul agent...
           Version: 'v1.7.0'
           Node ID: 'c43eedeb-f211-dbf2-e3fa-3caa64f86ddb'
         Node name: 'DESKTOP-77V3R9P'
        Datacenter: 'dc1' (Segment: '<all>')
            Server: true (Bootstrap: false)
       Client Addr: [127.0.0.1] (HTTP: 8500, HTTPS: -1, gRPC: 8502, DNS: 8600)
      Cluster Addr: 127.0.0.1 (LAN: 8301, WAN: 8302)
           Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false, Auto-Encrypt-TLS: false

==> Log data will now stream in as it occurs:

    2020-02-22T15:34:07.878+0800 [DEBUG] agent: Using random ID as node ID: id=c43eedeb-f211-dbf2-e3fa-3caa64f86ddb
    2020-02-22T15:34:07.900+0800 [DEBUG] agent.tlsutil: Update: version=1
    2020-02-22T15:34:07.914+0800 [DEBUG] agent.tlsutil: OutgoingRPCWrapper: version=1
    2020-02-22T15:34:07.916+0800 [INFO]  agent.server.raft: initial configuration: index=1 servers="[{Suffrage:Voter ID:c43eedeb-f211-dbf2-e3fa-3caa64f86ddb Address:127.0.0.1:8300}]"
    2020-02-22T15:34:07.916+0800 [INFO]  agent.server.raft: entering follower state: follower="Node at 127.0.0.1:8300 [Follower]" leader=
    2020-02-22T15:34:07.919+0800 [INFO]  agent.server.serf.wan: serf: EventMemberJoin: DESKTOP-77V3R9P.dc1 127.0.0.1
    2020-02-22T15:34:07.920+0800 [INFO]  agent.server.serf.lan: serf: EventMemberJoin: DESKTOP-77V3R9P 127.0.0.1
    2020-02-22T15:34:07.920+0800 [INFO]  agent.server: Adding LAN server: server="DESKTOP-77V3R9P (Addr: tcp/127.0.0.1:8300) (DC: dc1)"
    2020-02-22T15:34:07.921+0800 [INFO]  agent.server: Handled event for server in area: event=member-join server=DESKTOP-77V3R9P.dc1 area=wan
    2020-02-22T15:34:07.921+0800 [INFO]  agent: Started DNS server: address=127.0.0.1:8600 network=udp
    2020-02-22T15:34:07.923+0800 [INFO]  agent: Started DNS server: address=127.0.0.1:8600 network=tcp
    2020-02-22T15:34:07.926+0800 [INFO]  agent: Started HTTP server: address=127.0.0.1:8500 network=tcp
    2020-02-22T15:34:07.928+0800 [INFO]  agent: started state syncer
==> Consul agent running!
...

4.2、启动服务注册到 consul

分别启动provider-service服务和consumer-service服务，访问consul的Web UI界面可以看到两个服务都注册上来了：

4.3、调用测试接口

调用consumer-service测试接口 http://127.0.0.1:9090/test

现在尝试把provider服务停止，consul注册中心可以看到健康检查状态为Critical，服务已经下线

此时，再次调用 consumer-service 测试接口，会报找不到服务

5、Spring Cloud Consul 应用配置