简介
本文介绍在本地环境搭建ZooKeeper的伪集群环境的步骤,并且在Spring Boot环境下,如何使用ZooKeeper来注册服务。
本文参考了《架构探险》轻量级微服务架构 这本书。
本文示例代码:zookeeper-demo
搭建ZooKeeper伪集群
下载并安装
在官网下载ZooKeeper相关包后,解压到/etc/zookeeper下,并复制3份(ZooKeeper构建集群时,官网建议部署奇数个节点)。
安装ZooKeeper
修改配置
将conf/zoo_sample.cfg重命名为zoo.cfg,并将节点1修改为如下配置,具体意思请百度,这里不详细展开,因为这里配置的伪集群,所以要求各端口都不一样。
注意:在路径/home/billjiang/zookeeper/zkServer1
目录下需要建立一个myid文件,并在文件中写入内容1
节点1配置
# The number of milliseconds of each ticktickTime=2000initLimit=10syncLimit=5dataDir=/home/billjiang/zookeeper/zkServer1 clientPort=2181#clusterserver.1=127.0.0.1:2888:3888server.2=127.0.0.1:2889:3889server.3=127.0.0.1:2890:3890
节点2配置
# The number of milliseconds of each ticktickTime=2000initLimit=10syncLimit=5dataDir=/home/billjiang/zookeeper/zkServer2 clientPort=2182#clusterserver.1=127.0.0.1:2888:3888server.2=127.0.0.1:2889:3889server.3=127.0.0.1:2890:3890
节点3配置
# The number of milliseconds of each ticktickTime=2000initLimit=10syncLimit=5dataDir=/home/billjiang/zookeeper/zkServer3 clientPort=2183#clusterserver.1=127.0.0.1:2888:3888server.2=127.0.0.1:2889:3889server.3=127.0.0.1:2890:3890
批量启动集群shell脚本
为了启动集群,可以一个一个启动,也可以编写shell脚本批量启动:
zookeeper_start.sh
#!/bin/bash SERVERS="zkServer1 zkServer2 zkServer3" for SERVER in $SERVERS do echo "当前"$SERVER"正在启动...................." #ssh root@$SERVER "source /etc/profile;/usr/apps/zookeeper-3.4.9/bin/zkServer.sh start" sudo /etc/zookeeper/$SERVER/bin/zkServer.sh start echo $SERVER"启动结束--------------------------------------------" done
当然也可以编写批量停止的shell脚本。执行批量启动命令后,如下:
启动ZooKeeper集群
启动集群后,可使用bin/zkCli.sh命令查看ZooKeeper的节点数据。
以上完成了ZooKeeper伪集群的搭建。
服务注册实现
为了演示服务在ZooKeeper上的注册过程,本文这里启动了一个Maven项目zookeeper-learn,项目包含三个module
core 注册的核心逻辑
client 客户端服务1
client2 客户端服务2
zookeeper-learn
其中client/client2项目都依赖了core项目。在它们的pom.xml
配置了该依赖
<dependency> <groupId>com.cnpc</groupId> <artifactId>core</artifactId> <version>0.0.1-SNAPSHOT</version></dependency>
core项目的核心代码
定义服务注册接口ServiceRegistry
package com.example.core;public interface ServiceRegistry { /** * 注册服务信息 * * @param serviceName 服务名称 * @param serviceAddress 服务地址 */ void register(String serviceName, String serviceAddress); }
服务注册实现ServiceRegistryImpl
该服务实现将连接ZooKeeper集群,创建节点,并把服务的调用地址作为节点的值存储在该节点上。
package com.example.core;import org.apache.zookeeper.*;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.stereotype.Component;import java.util.concurrent.CountDownLatch;@Componentpublic class ServiceRegistryImpl implements ServiceRegistry, Watcher { private static Logger logger = LoggerFactory.getLogger(ServiceRegistryImpl.class); private static CountDownLatch latch = new CountDownLatch(1); private ZooKeeper zk; private static final int SESSION_TIMEOUT = 5000; public ServiceRegistryImpl() { } public ServiceRegistryImpl(String zkServers) { try { zk = new ZooKeeper(zkServers, SESSION_TIMEOUT, this); latch.await(); logger.debug("connected to zookeeper"); } catch (Exception ex) { logger.error("create zookeeper client failure", ex); } } private static final String REGISTRY_PATH = "/registry"; @Override public void register(String serviceName, String serviceAddress) { try { String registryPath = REGISTRY_PATH; if (zk.exists(registryPath, false) == null) { zk.create(registryPath, null, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); logger.debug("create registry node:{}", registryPath); } //创建服务节点(持久节点) String servicePath = registryPath + "/" + serviceName; if (zk.exists(servicePath, false) == null) { zk.create(servicePath, null, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); logger.debug("create service node:{}", servicePath); } //创建地址节点 String addressPath = servicePath + "/address-"; String addressNode = zk.create(addressPath, serviceAddress.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL); logger.debug("create address node:{} => {}", addressNode, serviceAddress); } catch (Exception e) { logger.error("create node failure", e); } } @Override public void process(WatchedEvent watchedEvent) { if (watchedEvent.getState() == Event.KeeperState.SyncConnected) latch.countDown(); } }
客户端注册服务
客户端在启动时,会将自身服务节点注册到ZooKeeper集群中。
application.properties配置
server.address=127.0.0.1 server.port=8080 registry.servers=127.0.0.1:2181,127.0.0.1:2182,127.0.0.1:2183
服务注册配置RegistryConfig
这样客户端可以读取appliaction.properties的ZooKeeper配置
package com.example.client;import com.example.core.ServiceRegistry;import com.example.core.ServiceRegistryImpl;import org.springframework.boot.context.properties.ConfigurationProperties;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;@Configuration@ConfigurationProperties(prefix = "registry")public class RegistryConfig { private String servers; @Bean public ServiceRegistry serviceRegistry() { return new ServiceRegistryImpl(servers); } public void setServers(String servers) { this.servers = servers; } }
用来测试的服务接口:TestController
@RestControllerpublic class TestController { @RequestMapping(name="HelloService",method = RequestMethod.GET,path = "/hello") public String hello(){ return "Hello"; } }
在项目启动的时候会将注解中name属性有值的方法注册到ZooKeeper集群中,
package com.example.client;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Value;import org.springframework.context.ApplicationContext;import org.springframework.stereotype.Component;import javax.servlet.ServletContext;import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;import com.example.core.ServiceRegistry;import org.springframework.web.context.support.WebApplicationContextUtils;import org.springframework.web.method.HandlerMethod;import org.springframework.web.servlet.mvc.method.RequestMappingInfo;import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;import java.util.Map;@Componentpublic class WebListener implements ServletContextListener { @Value("${server.address}") private String serverAddress; @Value("${server.port}") private int serverPort; @Autowired public ServiceRegistry serviceRegistry; @Override public void contextInitialized(ServletContextEvent sce) { ServletContext servletContext=sce.getServletContext(); ApplicationContext applicationContext= WebApplicationContextUtils.getRequiredWebApplicationContext(servletContext); RequestMappingHandlerMapping mapping=applicationContext.getBean(RequestMappingHandlerMapping.class); Map<RequestMappingInfo,HandlerMethod> infoMap=mapping.getHandlerMethods(); for (RequestMappingInfo info : infoMap.keySet()) { String serviceName=info.getName(); System.out.println("-----------------"+serviceName); if(serviceName!=null){ //注册服务 serviceRegistry.register(serviceName,String.format("%s:%d",serverAddress,serverPort)); } } } @Override public void contextDestroyed(ServletContextEvent sce) { } }
同样在client2项目中,相同的代码,唯一的区别就是client2的application.properties的server.port=8082
同时启动两个client2项目后,通过bin/zkCli.sh命令,连接到任意的一台ZooKeeper节点(因为ZooKeeper几点之间数据会保持同步)。显示如下信息:
[zk: localhost:2181(CONNECTED) 18] ls /registry/HelloService [address-0000000004, address-0000000003]
使用get
查看子节点的值
get /registry/HelloService/address-0000000003 127.0.0.1:8080 cZxid = 0x100000026 ctime = Wed Aug 09 18:00:56 CST 2017 mZxid = 0x100000026 mtime = Wed Aug 09 18:00:56 CST 2017 pZxid = 0x100000026 cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x15dc5782fe8000d dataLength = 14 numChildren = 0
get /registry/HelloService/address-0000000004 127.0.0.1:8081 cZxid = 0x100000028 ctime = Wed Aug 09 18:03:05 CST 2017 mZxid = 0x100000028 mtime = Wed Aug 09 18:03:05 CST 2017 pZxid = 0x100000028 cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x15dc5782fe8000e dataLength = 14 numChildren = 0
当停掉一台客户端client后,再次使用ls 命令,只显示address-0000000004
以上代码完成了ZooKeeper的服务注册。
作者:billJiang
链接:https://www.jianshu.com/p/0dfac0ad266f