Spring Cloud Netfix Eureka

程序员小强

发布于 2019-06-03 16:17:34

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发布于 2019-06-03 16:17:34

Eureka是什么 Eureka是Netflix开发的服务发现框架，本身是一个基于REST的服务，主要用于定位运行在AWS域中的中间层服务，以达到负载均衡和中间层服务故障转移的目的。SpringCloud将它集成在其子项目spring-cloud-netflix中，以实现SpringCloud的服务发现功能。

Eureka入门

Eureka分为两个组件: Eureka-server端和Eureka-client端

Eureka-server提供服务发现的功能,各个微服务启动时,会向Eureka Server注册自己的信息(例如: IP、port、微服务名称等)

Eureka-client是一个java客户端,用于简化与Eureka-server的交互(启动时,会向server注册自己的信息)

Eureka架构

1、服务启动后,会周期性(默认30秒)的向Eureka-server注册自己的信息以续约自己的“租期”

2、如果Eureka-server在一段时间内没有接收到某个微服务实例的心跳(以最后一次续约时间开始计算),Eureka-server将会注销这个实例(默认90秒)

3、默认情况下,Eureka-server同事也是Eureka-client. 多个Eureka-server实例, 互相之间通过增量复制的方式,来实现服务注册表的数据同步.

4、Eureka-server默认保证90秒内,Eureka-server集群内的所有实例数据到达一致, 从这个架构来看, Eureka-server所有实例所处的角色是对等的, 没有类似zookeeper、选举过程, 也不存在主从, 所有节点都是主节点.

5、Eureka-client会缓存注册表中的信息. 微服务无需每次请求都查询Eureka-server, 从而降低了Eureka-server的压力,其次Eureka-server所有节点都宕机了,服务消费者可以使用缓存中的信息找到服务提供者并完成调用.

Eureka搭建

1、创建spirngboot父子工程

2、父pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.spring.hello</groupId>
    <artifactId>hello-spring</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>hello-spring</name>
    <packaging>pom</packaging>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <modules>
        <module>eureka-server</module>
        <module>eureka1-consumer</module>
        <module>eureka1-provider</module>
    </modules>

    <dependencies>
        <dependency>
            <groupId>com.google.guava</groupId>
            <artifactId>guava</artifactId>
            <version>27.1-jre</version>
        </dependency>
    </dependencies>

    <!--引入springcloud的版本-->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.SR2</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>
</project>

3、创建eureka服务端: eureka-server

创建module,选择springboot工程,填写相关信息

选择Cloud Discovery, 勾住Eureka Server

eureka-server创建完成

接下来创建构建pom.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.spring.hello</groupId>
        <artifactId>hello-spring</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.george1</groupId>
    <artifactId>eureka-server</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>eureka-server</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

在主类中, 加上注解: @EnableEurekaServer

配置文件,用的是yml:

server:
     port: 9000
eureka:
     client:
        # 表示是否将自己注册到Eureka-server，默认为true，由于当前服务就是Eureka-server，故为false
         register-with-eureka: false
        # 表示是否从Eureka-server获取数据，默认为false，由于当前是单个节点，所以不需要从其他节点同步数据
         fetch-registry: false

4、创建eureka生产端: eureka-provider

创建流程同eureka-server, 选择的依赖不同,选择web和dicovery

eureka-provider的pom部分代码

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.0</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.46</version>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.6</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
    </dependencies>

在主类中增加注解: @EnableDiscoveryClient

application.yml的配置:

server:
  port: 8002

spring:
  application:
    name: ms-provider-order
  datasource:
    url: jdbc:mysql://ip:port/database_name
    driver-class-name: com.mysql.jdbc.Driver
    username: xxx
    password: xxx
  main:
    allow-bean-definition-overriding: true #当遇到相同名字的时候，是否允许覆盖注册


eureka:
  instance:
    instance-id: ms-provider-order-8002
    prefer-ip-address: true #以IP地址注册到服务中心，相互注册使用IP地址

mybatis:
  configuration:
    map-underscore-to-camel-case: true

provider端,使用springmvc+mybatis

controller端提供http接口

@RestController
@RequestMapping("/order")
public class OrderController {

    @Autowired
    private OrderService orderService;

    @RequestMapping("/queryOrdersByUserId/{userId}")
    public List<OrderVo> queryOrdersByUserId(@PathVariable Integer userId){
        return orderService.queryOrdersByUserId(userId);
    }
}

service层和dao层处理逻辑: 根据userId从mysql查出这个用户所有的订单记录

5、创建eureka消费端: eureka-consumer

创建流程同eureka-provider

在主类中增加注解: @EnableDiscoveryClient

pom.xml文件

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.0</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.46</version>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.6</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
    </dependencies>

在主类中增加注解: @EnableDiscoveryClient

application.xml中增加配置:

server:
  port: 8001
spring:
  application:
    name: ms-consumer-user
  datasource:
    url: jdbc:mysql://ip:port/database_name
    driver-class-name: com.mysql.jdbc.Driver
    username: xxx
   password: xxx
  main:
#    当遇到相同名字的时候，是否允许覆盖注册
    allow-bean-definition-overriding: true

eureka:
  instance:
    instance-id: ms-consumer-user-8001

mybatis:
  configuration:
    map-underscore-to-camel-case: true

controller层通过微服务名称MS-PROVIDER-ORDER来调用生产者

@RestController
@RequestMapping("/user")
@Slf4j
public class UserController {

    @Autowired
    private RestTemplate restTemplate;

    @Autowired
    private UserServiceImpl userService;

    @RequestMapping("queryUserInfoById/{userId}")
    public UserInfoVo queryUserInfoByid(@PathVariable("userId") Integer userId) {
        User user = userService.queryUserById(userId);
        ResponseEntity<List> responseEntity = restTemplate.getForEntity("http://MS-PROVIDER-ORDER/order/queryOrdersByUserId/" + userId, List.class);
        List<OrderVo> orderVoList = responseEntity.getBody();

        UserInfoVo userInfoVo = new UserInfoVo();
        userInfoVo.setOrderVoList(orderVoList);
        userInfoVo.setUserName(user.getUserName());
        return userInfoVo;
    }
}

Eureka web页面展示

在浏览器中输入:

http://127.0.0.1:8001/order/queryOrdersByUserId/1

通过微服务名称来访问数据

{
    "userName": "张三",
    "orderVoList": [
        {
            "orderId": 1,
            "orderMoney": 110.2,
            "userId": 1
        },
        {
            "orderId": 4,
            "orderMoney": 200.5,
            "userId": 1
        }
    ]
}

本文搭建了单机的eureka的微服务,接下来的文章,小强将介绍多台eureka-server高可用架构实践和注册中心安全登录.

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原始发表：2019-06-03，如有侵权请联系 cloudcommunity@tencent.com 删除

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