原文来自《重新定义Spring Cloud实战》
Eureka简介
Eureka是Netflix公司开源的一款服务发现组件，该组件提供的服务发现可以为负载均衡、failover等提供支持。Eureka包括EurekaServer及EurekaClient。EurekaServer提供REST服务，而EurekaClient则是使用Java编写的客户端，用于简化与EurekaServer的交互。
EurekaServer端采用的是P2P的复制模式，但是它不保证复制操作一定能成功，因此它提供的是一个最终一致性的服务实例视图；Client端在Server端的注册信息有一个带期限的租约，一旦Server端在指定期间没有收到Client端发送的心跳，则Server端会认为Client端注册的服务是不健康的，定时任务会将其从注册表中删除。Consul与Eureka不同，Consul采用Raft算法，可以提供强一致性的保证，Consul的agent相当于Netflix Ribbon+Netflix Eureka Client，而且对应用来说相对透明，同时相对于Eureka这种集中式的心跳检测机制，Consul的agent可以参与到基于gossip协议的健康检查，分散了Server端的心跳检测压力。除此之外，Consul为多数据中心提供了开箱即用的原生支持等。
Hello World Demo
环境配置
- JDK8
- Maven
Eureka Server
- 依赖配置
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka-server</artifactId>
</dependency>
- 编码
@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServerApplication.class, args);
}
}
- 配置
server:
port: 8888
eureka:
instance:
hostname: localhost
client:
registerWithEureka: false
fetchRegistry: false
serviceUrl:
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
Eureka Client
- 依赖配置
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
- 编码
@SpringBootApplication
@EnableDiscoveryClient
public class ClientApplication {
public static void main(String[] args) {
SpringApplication.run(ClientApplication.class, args);
}
}
- 配置
server:
port: 7070
spring:
application:
name: client-a
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8888/eureka/
instance:
prefer-ip-address: true
management:
security:
enabled: false
Eureka Admin 管控平台
Eureka Admin 管控平台是Spring Cloud中国社区为Eureka注册中心开源的一个节点监控、服务动态启停的项目。
由于目前尚未提交中央仓库，需下载源码构建！
- 依赖配置
<dependency>
<groupId>cn.springcloud.eureka</groupId>
<artifactId>eureka-admin-utils</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>cn.springcloud.eureka</groupId>
<artifactId>eureka-admin-view</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
- 编码
@Configuration
public class WebMvcConfiguration extends WebMvcConfigurerAdapter {
private final Logger logger = LoggerFactory.getLogger(WebMvcConfiguration.class);
@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
// converters.add(new FastJsonHttpMessageConverter4());
}
@Override
public void addInterceptors(InterceptorRegistry registry) {
logger.info("添加拦截器");
registry.addInterceptor(new PerformanceInterceptor());
}
@Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addRedirectViewController("/", "/eurekaindex.html");
}
}
@RestController
@RequestMapping("eureka")
public class EurekaClientController {
@Resource
private EurekaClient eurekaClient;
/**
* @description 获取服务数量和节点数量
*/
@RequestMapping(value = "home", method = RequestMethod.GET)
public ResultMap home(){
List<Application> apps = eurekaClient.getApplications().getRegisteredApplications();
int appCount = apps.size();
int nodeCount = 0;
int enableNodeCount = 0;
for(Application app : apps){
nodeCount += app.getInstancesAsIsFromEureka().size();
List<InstanceInfo> instances = app.getInstances();
for(InstanceInfo instance : instances){
if(instance.getStatus().name().equals(InstanceStatus.UP.name())){
enableNodeCount ++;
}
}
}
return ResultMap.buildSuccess().put("appCount", appCount).put("nodeCount", nodeCount).put("enableNodeCount", enableNodeCount);
}
/**
* @description 获取所有服务节点
*/
@RequestMapping(value = "apps", method = RequestMethod.GET)
public ResultMap apps(){
List<Application> apps = eurekaClient.getApplications().getRegisteredApplications();
Collections.sort(apps, new Comparator<Application>() {
public int compare(Application l, Application r) {
return l.getName().compareTo(r.getName());
}
});
for(Application app : apps){
Collections.sort(app.getInstances(), new Comparator<InstanceInfo>() {
public int compare(InstanceInfo l, InstanceInfo r) {
return l.getPort() - r.getPort();
}
});
}
return ResultMap.buildSuccess().put("list", apps);
}
/**
* @description 界面请求转到第三方服务进行状态变更
*/
@RequestMapping(value = "status/{appName}", method = RequestMethod.POST)
public ResultMap status(@PathVariable String appName, String instanceId, String status){
Application application = eurekaClient.getApplication(appName);
InstanceInfo instanceInfo = application.getByInstanceId(instanceId);
instanceInfo.setStatus(InstanceStatus.toEnum(status));
Map<String, String> headers = new HashMap<>();
headers.put("Content-Type", "text/plain");
// HttpUtil.post(instanceInfo.getHomePageUrl() + "eureka-admin-client/status", "status=" + status);
HttpUtil.post(instanceInfo.getHomePageUrl() + "service-registry/instance-status", status, headers);
// List<InstanceInfo> instanceInfos = application.getInstances();
// for(InstanceInfo item : instanceInfos){
// HttpUtil.post(item.getHomePageUrl() + "eureka-admin-client/status/" + appName, "instanceId=" + instanceId + "&status=" + status);
// }
// Set<String> regions = eurekaClient.getAllKnownRegions();
// for(String region : regions){
// Applications applications = eurekaClient.getApplicationsForARegion(region);
// List<Application> apps = applications.getRegisteredApplications();
// for(Application app : apps){
// eurekaClient.getApplications().addApplication(app);
// }
// }
return ResultMap.buildSuccess();
}
}
@EnableEurekaClient
@SpringBootApplication
public class EurekaAdminServer {
public static void main(String[] args) {
SpringApplication.run(EurekaAdminServer.class, args);
}
}
- 配置
server:
port: 8082
eureka:
server:
eviction-interval-timer-in-ms: 30000
client:
register-with-eureka: false
fetch-registry: true
filterOnlyUpInstances: false
serviceUrl:
defaultZone: http://localhost:8888/eureka/
logging:
level:
com:
itopener: DEBUG
org:
springframework: INFO
验证
- 访问 eureka server 站点 : http://localhost:8888/
image.png
- 访问 eureka 管控平台站点 : http://localhost:8082/eurekaindex.html
image.png
