Spring Cloud Eureka

 

搭建服务注册中心

创建eureka-center，pom.xml如下：

<?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>

    <groupId>org.mythsky</groupId>
    <artifactId>eureka-center</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>eureka-center</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Edgware.RELEASE</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka-server</artifactId>
        </dependency>
        <!--<dependency>-->
            <!--<groupId>org.mybatis.spring.boot</groupId>-->
            <!--<artifactId>mybatis-spring-boot-starter</artifactId>-->
            <!--<version>1.3.1</version>-->
        <!--</dependency>-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

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

    <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>

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


</project>

在Spring Boot启动类上添加@EnableEurekaServer

@EnableEurekaServer
@SpringBootApplication
public class EurekaCenterApplication {

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

编辑application.properties

server.port=1111

eureka.instance.hostname=localhost
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false
eureka.client.service-url.defaultZone=http://${eureka.instance.hostname}:${server.port}/eureka/

eureka.server.enable-self-preservation=false

eureka.client.register-with-eureka=false

默认设置下，服务中心会将自己作为客户端来注册自己，所以这里配置为false

eureka.client.fetch-registry=false

禁用检索服务

eureka.server.enable-self-preservation=false

禁用Eureka Server的自我保护机制，Eureka Server在运行期间会统计心跳失败的比例在15分钟内是否低于85%，在单机调试时很容易满足，从而不能正常调用服务

 

这里还需要注意一个设置，这个设置也是在自我保护机制关闭的情况下生效

eureka.server.eviction-interval-timer-in-ms=5000

这个设置是eureka server 每5秒钟剔除失效的服务，这个配合服务提供端的设置生效

比如服务提供端有如下配置

eureka.instance.lease-renewal-interval-in-seconds=10
eureka.instance.lease-expiration-duration-in-seconds=15

意思是服务提供端每10秒发送一次服务续约，服务的失效时间为15秒，即如果服务端下线，15秒后eureka server将其服务剔除，如果上面的主动剔除时间设为30秒，那么这里会在30秒后剔除服务

还有一个服务消费端获取服务的设置

eureka.client.registry-fetch-interval-seconds=10

表示每10s获取一次服务列表

如果在10s内服务提供端下线并重新上线，服务消费端还没有拉取最新服务地址，会出现连接超时报错

 

 

继续将服务提供端下线，10s后消费端重新获取服务地址，此时再调用服务，会提示没有可用服务

 

运行后访问：http://localhost:1111/，即可看到如下界面：

这里的红色提示是因为我们上面的配置关闭了自我保护。

高可用注册中心

创建application-peer1.properties

spring.application.name=eureka-server
server.port=1111

eureka.instance.hostname=peer1
eureka.client.service-url.defaultZone=http://peer2:1112/eureka/

创建application-peer2.properties

spring.application.name=eureka-server
server.port=1112

eureka.instance.hostname=peer2
eureka.client.service-url.defaultZone=http://peer1:1111/eureka/

在host中添加转换

127.0.0.1    peer1
127.0.0.1    peer2

通过spring.profiles.active 分别启动peer1 和peer2

java -jar eureka-center-0.0.1-SNAPSHOT.jar --spring.profiles.active=peer1
java -jar eureka-center-0.0.1-SNAPSHOT.jar --spring.profiles.active=peer2

这里要注意，在application-peer2.properties中没配置但在application.properties中有配置的话依旧会读取application.properties中的内容

还需要注意的是eureka.instance.prefer-ip-address=true这个配置，在这个配置下eureka.client.service-url.defaultZone=http://${spring.security.user.name}:${spring.security.user.password}@172.26.10.110:8090/eureka/

这里可以用IP+port，此时可以不设置eureka.instance.hostname

如果eureka.instance.prefer-ip-address=false，eureka.client.service-url.defaultZone里面可以用域名yourdomain:8090/eureka，此时必须设置eureka.instance.hostname=yourdomain

从下面的界面即可看到

打开http://localhost:1111/

 

 打开http://localhost:1112/

 这里可以看到replicas都是不可用的

修复上面的问题，正确结果应该如下

 

这里还有两个重要属性

eureka.instance.lease-renewal-interval-in-seconds=30
eureka.instance.lease-expiration-duration-in-seconds=90

第一个用于定义服务续约任务的调用时间，默认30秒

第二个用于定义服务失效的时间，默认90秒

 服务提供者

新建一个Spring Boot项目，添加pom依赖

<?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>

    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Edgware.RELEASE</spring-cloud.version>
    </properties>

    <dependencies>
        <!--<dependency>-->
            <!--<groupId>org.mybatis.spring.boot</groupId>-->
            <!--<artifactId>mybatis-spring-boot-starter</artifactId>-->
            <!--<version>1.3.1</version>-->
        <!--</dependency>-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <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>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

在入口添加@EnableDiscoveryClient

@EnableDiscoveryClient
@SpringBootApplication
public class DemoApplication {

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

添加一个控制器

@RestController
public class HelloController {
    private  final Logger logger=Logger.getLogger(String.valueOf(getClass()));
    @Autowired
    private DiscoveryClient client;
    @RequestMapping(value = "/hello",method = RequestMethod.GET)
    public String index(){
        ServiceInstance instance=client.getLocalServiceInstance();
        logger.info("/hello,host:"+instance.getHost()+", service_id:"+instance.getServiceId());
        return "hello world";
    }
}

新版接口中无法使用client.getLocalServiceInstance()

更改如下

        String serviceId=client.getServices().get(0);
        ServiceInstance instance=client.getInstances(serviceId).get(0);

 

在配置中应用服务名称及服务中心地址

server.port=8080
management.security.enabled=false
spring.application.name=hello-service
eureka.client.service-url.defaultZone=http://localhost:1111/eureka/,http://localhost:1112/eureka/

启动服务，在Eureka界面即可看到注册的服务

 

 同时在控制台中可以看到日志

 

在Idea中点击Exit

可以看到服务立刻下线

如果是点击上面的Stop，并不能立刻看到服务下线，而是等到上面的轮询时间才能看到。

 

服务发现和消费

新建Spring Boot项目，取名为ribbon-consumer，pom如下

<?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>

    <groupId>org.mythsky</groupId>
    <artifactId>ribbon-consumer</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>ribbon-consumer</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Edgware.RELEASE</spring-cloud.version>
    </properties>

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

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

    <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>

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


</project>

应用入口处添加@EnableDiscoveryClient和@LoadBalanced开启客户端负载均衡

@EnableDiscoveryClient
@SpringBootApplication
public class RibbonConsumerApplication {

    @Bean
    @LoadBalanced
    RestTemplate restTemplate(){
        return new RestTemplate();
    }

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

添加控制器

@RestController
public class ConsumerController {
    @Autowired
    RestTemplate restTemplate;
    @RequestMapping(value = "/ribbon-consumer",method = RequestMethod.GET)
    public String helloConsumer(){
        return restTemplate.getForEntity("http://hello-service/hello",String.class).getBody();
    }
}

修改配置

spring.application.name=ribbon-consumer
server.port=9000

eureka.client.service-url.defaultZone=http://localhost:1111/eureka/

启动应用，访问http://localhost:9000/ribbon-consumer，会看到返回了服务提供的信息

此时在Eureka界面可以看到

多次刷新消费页面，观察两个注册中心的日志，可以看到两个中心轮流提供服务

 

启用安全认证

在注册中心启用security

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

配置

spring.security.user.name=user
spring.security.user.password=pwd123
eureka.client.service-url.defaultZone=http://${spring.security.user.name}:${spring.security.user.password}@${eureka.instance.hostname}:${server.port}/eureka/

由于spring默认开启csrf，所以做如下修改

@Configuration
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.csrf().disable();
        super.configure(http);
    }
}

服务提供者配置

service.username=user
service.password=pwd123
eureka.client.service-url.defaultZone=http://${service.username}:${service.password}@localhost:1111/eureka/

这样就能实现安全认证了。