Eureka 注册中心

简述

在Eureka架构中，微服务角色有两类:

• EurekaServer:服务端，注册中心
  • 记录服务信息
  • 心跳监控
• EurekaClient:客户端
  • Provider:服务提供者，例如案例中的user-service
    • 注册自己的信息到EurekaServer
    • 每隔30秒向EurekaServer发送心跳
  • consumer:服务消费者，例如案例中的order-service
    • 根据服务名称从EurekaServer拉取服务列表
    • 基于服务列表做负载均衡，选中一个微服务后发起远程调用

注册发现

1．搭建EurekaServer

• 引入eureka-server依赖

  <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
  </dependency>
  

• 添加@EnableEurekaServer注解

  @SpringBootApplication
  @EnableEurekaServer
  public class EurekaMain{
      public static void main(String[] args) {
          SpringApplication.run(EurekaMain.class, args);
      }
  }
  

• 在application.yml中配置eureka地址

  server:
    port: 7001
  eureka:
    instance:
      hostname: eureka-server
    client:
      # 不向注册中心注册自己
      register-with-eureka: false
      # 表示自己是注册中心，提供维护服务，不需要检索服务
      fetch-registry: false
      service-url:
        defaultZone: http://eureka7001.com:7001/eureka
  

2．服务注册

• 引入eureka-client依赖

  <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
  </dependency>
  

• 在application.yml中配置eureka地址

  eureka:
    client:
      fetch-registry: true
      register-with-eureka: true
      service-url:
        defaultZone: http://localhost:7001/eureka
    instance:
      instance-id: payment
  

• 启动类上加注解

  @SpringBootApplication
  @EnableEurekaClient
  @EnableDiscoveryClient
  public class PaymentMain {
      public static void main(String[] args) {
          SpringApplication.run(PaymentMain.class, args);
      }
  }
  

3．服务发现

• 引入eureka-client依赖

  <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
  </dependency>
  

• 在application.yml中配置eureka地址

  eureka:
    client:
      fetch-registry: true
      register-with-eureka: true
      service-url:
        defaultZone: http://localhost:7001/eureka
  spring:
    application:
      name: cloud-order-service
  

• 给RestTemplate添加@LoadBalanced注解

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

@RestController
@Slf4j
public class OrderController {

    public static final String PAYMENT_URL = "http://CLOUD-PAYMENT-SERVICE";

    @Resource
    private RestTemplate restTemplate;

    @GetMapping("/consumer/payment/create")
    public CommonResult<Payment> create(Payment payment) {
        return restTemplate.postForObject(PAYMENT_URL + "/payment/create", payment, CommonResult.class);
    }

    @GetMapping("/consumer/payment/get/{id}")
    public CommonResult<Payment> getPayment(@PathVariable("id") Long id) {
        return restTemplate.getForObject(PAYMENT_URL + "/payment/get/" + id, CommonResult.class);
    }

禁止自我保护

eureka:
  server:
    enable-self-preservation: false			#默认开启
    eviction-interval-timer-in-ms: 2000		#2s

THE SELF PRESERVATION MODE IS TURNED OFF. THIS MAY NOT PROTECT INSTANCE EXPIRY IN CASE OF NETWORK/OTHER PROBLEMS.