实践 Zookeeper

本文包含的内容：

• 如何安装ZK
• 如何启动ZK
• 如何查看ZK的数据
• ZK有哪些用途

安装ZK

不需要安装。跟下载tomcat、kafka等等一样，解压即可，不过它需要依赖jdk，因此PATH环境变量中要包含java。

方法1：从官网下载，解压之后，bin目录下，有window和linux的运行命令，window的命令结尾是 xx.cmd，linux和mac是 xxx.sh。

$ tree -L 1
.
├── bin
│   ├── README.txt
│   ├── zkCleanup.sh
│   ├── zkCli.cmd
│   ├── zkCli.sh
│   ├── zkEnv.cmd
│   ├── zkEnv.sh
│   ├── zkServer.cmd
│   ├── zkServer-initialize.sh
│   ├── zkServer.sh
│   ├── zkSnapshotComparer.cmd
│   ├── zkSnapshotComparer.sh
│   ├── zkSnapShotToolkit.cmd
│   ├── zkSnapShotToolkit.sh
│   ├── zkTxnLogToolkit.cmd
│   └── zkTxnLogToolkit.sh
├── conf
│   ├── configuration.xsl
│   ├── logback.xml
│   └── zoo_sample.cfg
├── docs
├── lib
├── LICENSE.txt
├── NOTICE.txt
├── README.md
└── README_packaging.md

方法2： 下载kafka之后，它里面自带ZK。例如：~/soft/kafka_2.13-2.8.0

可以看到kafka的bin目录下面，有启动和停止ZK相关的命令：zookeeper-server-start.sh，zookeeper-server-stop.sh。

~/soft/kafka_2.13-2.8.0
├── bin
│   ├── connect-distributed.sh
│   ├── connect-mirror-maker.sh
│   ├── connect-standalone.sh
│   ├── kafka-acls.sh
│   ├── kafka-broker-api-versions.sh
│   ├── kafka-cluster.sh
│   ├── kafka-configs.sh
│   ├── kafka-console-consumer.sh
│   ├── kafka-console-producer.sh
│   ├── kafka-consumer-groups.sh
│   ├── kafka-consumer-perf-test.sh
│   ├── kafka-delegation-tokens.sh
│   ├── kafka-delete-records.sh
│   ├── kafka-dump-log.sh
│   ├── kafka-features.sh
│   ├── kafka-leader-election.sh
│   ├── kafka-log-dirs.sh
│   ├── kafka-metadata-shell.sh
│   ├── kafka-mirror-maker.sh
│   ├── kafka-preferred-replica-election.sh
│   ├── kafka-producer-perf-test.sh
│   ├── kafka-reassign-partitions.sh
│   ├── kafka-replica-verification.sh
│   ├── kafka-run-class.sh
│   ├── kafka-server-start.sh
│   ├── kafka-server-stop.sh
│   ├── kafka-storage.sh
│   ├── kafka-streams-application-reset.sh
│   ├── kafka-topics.sh
│   ├── kafka-verifiable-consumer.sh
│   ├── kafka-verifiable-producer.sh
│   ├── trogdor.sh
│   ├── windows
│   ├── zookeeper-security-migration.sh
│   ├── zookeeper-server-start.sh
│   ├── zookeeper-server-stop.sh
│   └── zookeeper-shell.sh

├── config
│   ├── connect-console-sink.properties
│   ├── connect-console-source.properties
│   ├── connect-distributed.properties
│   ├── connect-file-sink.properties
│   ├── connect-file-source.properties
│   ├── connect-log4j.properties
│   ├── connect-mirror-maker.properties
│   ├── connect-standalone.properties
│   ├── consumer.properties
│   ├── kraft
│   ├── log4j.properties
│   ├── producer.properties
│   ├── server1.properties
│   ├── server.properties
│   ├── tools-log4j.properties
│   ├── trogdor.conf
│   └── zookeeper.properties
├── libs
├── LICENSE
├── licenses
├── logs
├── NOTICE
└── site-docs

如何启动ZK

这个更简单了，bin目录下，有启动脚本，直接执行即可，不过需要注意启动参数。

如果使用kafka集成的ZK，启动命令（在bin目录下，window系统）：zookeeper-server-start.bat ..\..\config\zookeeper.properties

针对 Window 环境，可以在user home目录定义一个脚本（名字：startZK.bat），然后从Start菜单打开cmd，直接执行脚本即可快速启动ZK（省去了切换目录，然后敲命令），然后关闭的话，直接 Ctrl + C 即可停掉ZK。

@echo on
cd C:\develop\soft\kafka_2.13-2.8.0\bin\windows
zookeeper-server-start.bat ..\..\config\zookeeper.properties
pause

如何查看ZK的数据

要查看ZooKeeper中的数据，你可以使用ZooKeeper自带的CLI（命令行接口）客户端，名为zkCli.sh（在Unix/Linux上）或zkCli.cmd（在Windows上）。这是一个交互式的shell，可以用来执行各种ZooKeeper命令。

以下是如何使用zkCli来查看ZooKeeper中的数据的基本步骤：

1. 启动zkCli客户端
   在你的ZooKeeper安装目录中，打开终端或命令行窗口，然后运行对应的zkCli命令。
2. 连接到ZooKeeper服务器
   默认情况下，zkCli会尝试连接到localhost:2181。如果你的ZooKeeper服务器配置在其他地址或端口，可以使用-server参数指定，如：

zkCli.sh -server your.zookeeper.server:2181

• 列出ZooKeeper中的znodes
  一旦连接到ZooKeeper服务器，你可以使用ls命令来查看根目录下的znodes：

[zk: your.zookeeper.server:2181(CONNECTED) 0] ls / 

• 查看znode的数据
  使用get命令 followed by the znode路径来查看znode的数据：

[zk: your.zookeeper.server:2181(CONNECTED) 1] get /myznode

• 执行其他操作
  你可以使用其他命令（如create, set, delete等）来在ZooKeeper中执行操作。

• 退出zkCli客户端
  使用quit命令来退出客户端：

[zk: your.zookeeper.server:2181(CONNECTED) 2] quit

此外，也有第三方工具和UI界面，如ZooInspector或Kazoo, 供你查看和管理ZooKeeper数据。但是，对于简单的操作，zkCli应该足够了。

ZK有哪些用途

Dubbo应用使用ZK作为注册中心

代码来源：Spring Boot 快速开发 Dubbo 服务 | Apache Dubbo

在Dubbo应用程序中，一般使用ZK作为注册中心，启动ZK之后，再接着启动provider和consumer两个服务，他们会把自己注册到ZK中，然后通过相同的名字找到彼此。

# provider启动输出的log
[main] org.apache.dubbo.config.ServiceConfig    :  [DUBBO] Successfully registered interface application mapping for service org.apache.dubbo.springboot.demo.DemoService, dubbo version: 3.2.0, current host: 172.17.0.1
[main] o.a.d.r.zookeeper.ZookeeperRegistry      :  [DUBBO] Notify urls for subscribe url provider://172.17.0.1:20881/org.apache.dubbo.metadata.MetadataService?anyhost=true&application=dubbo-springboot-demo-provider&background=false&bind.ip=172.17.0.1&bind.port=20881&category=configurators&check=false&delay=0&deprecated=false&dubbo=2.0.2&dynamic=true&executor-management-mode=isolation&file-cache=true&generic=false&getAndListenInstanceMetadata.1.callback=true&getAndListenInstanceMetadata.return=true&getAndListenInstanceMetadata.sent=true&group=dubbo-springboot-demo-provider&interface=org.apache.dubbo.metadata.MetadataService&methods=exportInstanceMetadata,getAndListenInstanceMetadata,getExportedServiceURLs,getExportedURLs,getExportedURLs,getExportedURLs,getExportedURLs,getExportedURLs,getInstanceMetadataChangedListenerMap,getMetadataInfo,getMetadataInfos,getMetadataURL,getServiceDefinition,getServiceDefinition,getSubscribedURLs,isMetadataService,serviceName,toSortedStrings,toSortedStrings,version&pid=428346&prefer.serialization=fastjson2,hessian2&qos.enable=true&register=false&release=3.2.0&revision=3.2.0&service-name-mapping=true&side=provider&timestamp=1694605314901&version=1.0.0, url size: 1, dubbo version: 3.2.0, current host: 172.17.0.1

[main] org.apache.dubbo.config.ServiceConfig    :  [DUBBO] Try to register interface application mapping for service dubbo-springboot-demo-provider/org.apache.dubbo.metadata.MetadataService:1.0.0, dubbo version: 3.2.0, current host: 172.17.0.1
[main] org.apache.dubbo.config.ServiceConfig    :  [DUBBO] Successfully registered interface application mapping for service dubbo-springboot-demo-provider/org.apache.dubbo.metadata.MetadataService:1.0.0, dubbo version: 3.2.0, current host: 172.17.0.1
[main] .c.m.ConfigurableMetadataServiceExporter :  [DUBBO] The MetadataService exports urls : [dubbo://172.17.0.1:20881/org.apache.dubbo.metadata.MetadataService?anyhost=true&application=dubbo-springboot-demo-provider&background=false&bind.ip=172.17.0.1&bind.port=20881&delay=0&deprecated=false&dubbo=2.0.2&dynamic=true&executor-management-mode=isolation&file-cache=true&generic=false&getAndListenInstanceMetadata.1.callback=true&getAndListenInstanceMetadata.return=true&getAndListenInstanceMetadata.sent=true&group=dubbo-springboot-demo-provider&interface=org.apache.dubbo.metadata.MetadataService&methods=exportInstanceMetadata,getAndListenInstanceMetadata,getExportedServiceURLs,getExportedURLs,getExportedURLs,getExportedURLs,getExportedURLs,getExportedURLs,getInstanceMetadataChangedListenerMap,getMetadataInfo,getMetadataInfos,getMetadataURL,getServiceDefinition,getServiceDefinition,getSubscribedURLs,isMetadataService,serviceName,toSortedStrings,toSortedStrings,version&pid=428346&prefer.serialization=fastjson2,hessian2&qos.enable=true&register=false&release=3.2.0&revision=3.2.0&service-name-mapping=true&side=provider&timestamp=1694605314901&version=1.0.0], dubbo version: 3.2.0, current host: 172.17.0.1
[main] o.a.d.r.c.m.ServiceInstanceMetadataUtils :  [DUBBO] Start registering instance address to registry., dubbo version: 3.2.0, current host: 172.17.0.1
[main] org.apache.dubbo.metadata.MetadataInfo   :  [DUBBO] metadata revision changed: null -> f32e16da1c6a0dbceb5e063f52ece15a, app: dubbo-springboot-demo-provider, services: 1, dubbo version: 3.2.0, current host: 172.17.0.1
[main] o.a.d.c.d.DefaultApplicationDeployer     :  [DUBBO] Dubbo Application[1.1](dubbo-springboot-demo-provider) is ready., dubbo version: 3.2.0, current host: 172.17.0.1
[main] o.a.d.s.d.provider.ProviderApplication   : Started ProviderApplication in 2.549 seconds (JVM running for 2.89)
[pool-1-thread-1] .b.c.e.AwaitingNonWebApplicationListener :  [Dubbo] Current Spring Boot Application is await...

# provider 退出输出log
[ionShutdownHook] o.a.d.registry.support.RegistryManager   :  [DUBBO] Close all registries [zookeeper://jack-win10.lan:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-springboot-demo-provider&dubbo=2.0.2&executor-management-mode=isolation&file-cache=true&interface=org.apache.dubbo.registry.RegistryService&pid=352356&qos.enable=true&release=3.2.0, zookeeper://jack-win10.lan:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-springboot-demo-provider&dubbo=2.0.2&executor-management-mode=isolation&file-cache=true&interface=org.apache.dubbo.registry.RegistryService&pid=352356&qos.enable=true&release=3.2.0], dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.a.d.r.zookeeper.ZookeeperRegistry      :  [DUBBO] Destroy registry:zookeeper://jack-win10.lan:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-springboot-demo-provider&dubbo=2.0.2&executor-management-mode=isolation&file-cache=true&interface=org.apache.dubbo.registry.RegistryService&pid=352356&qos.enable=true&release=3.2.0, dubbo version: 3.2.0, current host: 172.17.0.1
[tor-Framework-0] o.a.c.f.imps.CuratorFrameworkImpl        : backgroundOperationsLoop exiting
[ionShutdownHook] org.apache.zookeeper.ZooKeeper           : Session: 0x100006915a60007 closed

consumer那边的输出：

# 启动时的log
[           main] f.a.ReferenceAnnotationBeanPostProcessor :  [DUBBO] Register dubbo reference bean: demoService = ReferenceBean:org.apache.dubbo.springboot.demo.DemoService() at private org.apache.dubbo.springboot.demo.DemoService org.apache.dubbo.springboot.demo.consumer.Task.demoService, dubbo version: 3.2.0, current host: 172.17.0.1
[           main] f.a.ReferenceAnnotationBeanPostProcessor :  [DUBBO] class org.apache.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor was destroying!, dubbo version: 3.2.0, current host: 172.17.0.1
[           main] o.a.d.c.s.c.DubboConfigBeanInitializer   :  [DUBBO] loading dubbo config beans ..., dubbo version: 3.2.0, current host: 172.17.0.1
[           main] o.a.d.c.s.c.DubboConfigBeanInitializer   :  [DUBBO] dubbo config beans are loaded., dubbo version: 3.2.0, current host: 172.17.0.1
[           main] o.a.d.c.d.DefaultApplicationDeployer     :  [DUBBO] No value is configured in the registry, the DynamicConfigurationFactory extension[name : zookeeper] supports as the config center, dubbo version: 3.2.0, current host: 172.17.0.1
[           main] o.a.d.c.d.DefaultApplicationDeployer     :  [DUBBO] The registry[<dubbo:registry address="zookeeper://jack-win10.lan:2181" protocol="zookeeper" port="2181" />] will be used as the config center, dubbo version: 3.2.0, current host: 172.17.0.1
[           main] o.a.d.c.d.DefaultApplicationDeployer     :  [DUBBO] use registry as config-center: <dubbo:config-center highestPriority="false" id="config-center-zookeeper-jack-win10.lan-2181" address="zookeeper://jack-win10.lan:2181" protocol="zookeeper" port="2181" parameters="{client=null}" />, dubbo version: 3.2.0, current host: 172.17.0.1
[           main] org.apache.curator.utils.Compatibility   : Running in ZooKeeper 3.4.x compatibility mode

[nStateManager-0] o.a.d.r.z.c.CuratorZookeeperClient       :  [DUBBO] Curator zookeeper client instance initiated successfully, session id is 100006915a60014, dubbo version: 3.2.0, current host: 172.17.0.1

[           main] o.a.dubbo.config.context.ConfigManager   :  [DUBBO] <dubbo:registry address="zookeeper://jack-win10.lan:2181" protocol="zookeeper" port="2181" />, dubbo version: 3.2.0, current host: 172.17.0.1

# 退出时的log
[ionShutdownHook] org.apache.zookeeper.ZooKeeper           : Session: 0x100006915a60014 closed
[ain-EventThread] org.apache.zookeeper.ClientCnxn          : EventThread shut down for session: 0x100006915a60014
[ionShutdownHook] o.apache.dubbo.rpc.model.FrameworkModel  :  [DUBBO] Destroying default framework model: Dubbo Framework[1], dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.apache.dubbo.rpc.model.FrameworkModel  :  [DUBBO] Dubbo Framework[1] is destroying ..., dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.a.d.c.d.DefaultApplicationDeployer     :  [DUBBO] Dubbo Application[1.0](DUBBO_INTERNAL_APPLICATION) is stopping., dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.a.d.c.deploy.DefaultModuleDeployer     :  [DUBBO] Dubbo Module[1.0.0] is stopping., dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.a.d.c.deploy.DefaultModuleDeployer     :  [DUBBO] Dubbo Module[1.0.0] has stopped., dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.a.d.registry.support.RegistryManager   :  [DUBBO] Close all registries [], dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.a.d.c.t.m.DefaultExecutorRepository    :  [DUBBO] destroying application executor repository .., dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.a.d.c.d.DefaultApplicationDeployer     :  [DUBBO] Dubbo Application[1.0](DUBBO_INTERNAL_APPLICATION) has stopped., dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.apache.dubbo.rpc.model.FrameworkModel  :  [DUBBO] Dubbo Framework[1] is destroyed, dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.apache.dubbo.rpc.model.FrameworkModel  :  [DUBBO] Reset global default framework from Dubbo Framework[1] to null, dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.a.d.c.r.GlobalResourcesRepository      :  [DUBBO] Destroying global resources ..., dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.a.d.c.r.GlobalResourcesRepository      :  [DUBBO] Dubbo is completely destroyed, dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.a.d.c.t.m.FrameworkExecutorRepository  :  [DUBBO] destroying framework executor repository .., dubbo version: 3.2.0, current host: 172.17.0.1
[ionShutdownHook] o.a.d.c.s.c.DubboSpringInitializer       :  [DUBBO] Unbind Dubbo Module[1.1.1] from spring container: org.springframework.beans.factory.support.DefaultListableBeanFactory@e45f292, dubbo version: 3.2.0, current host: 172.17.0.1