ZooKeeper介绍
ZooKeeper是一个分布式的，开放源码的分布式应用程序协调服务，是Google的Chubby一个开源的实现，是Hadoop和Hbase的重要组件。它是一个为分布式应用提供一致性服务的软件，提供的功能包括：配置维护、域名服务、分布式同步、组服务等。
ZooKeeper的目标就是封装好复杂易出错的关键服务，将简单易用的接口和性能高效、功能稳定的系统提供给用户。
ZooKeeper包含一个简单的原语集， [1] 提供Java和C的接口。
官网：https://zookeeper.apache.org
ZooKeeper安装
安装环境：
1、系统：CentOS 7
2、Java环境：JDK8
zookeeper有单机、伪集群、集群三种部署方式，本例使用的zookeeper版本是：zookeeper-3.4.12
单机模式
下载ZooKeeper
地址：http://mirrors.hust.edu.cn/apache/zookeeper/
注意版本，启动报错可能找不到主类，可以下载源码版
解压
# 解压到local
tar -zxvf apache-zookeeper-3.5.8-bin.tar.gz -C /usr/local/
# 更改文件夹名称
mv apache-zookeeper-3.5.8-bin zookeeper
解压后目录如下：
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创建zoo.cfg
进入conf目录，创建一个zookeeper的配置文件zoo.cfg，可复制conf/zoo_sample.cfg作为配置文件
cd conf
cp zoo_sample.cfg zoo.cfg
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配置文件说明
# The number of milliseconds of each tick
# tickTime：CS通信心跳数
# Zookeeper 服务器之间或客户端与服务器之间维持心跳的时间间隔，也就是每个 tickTime 时间就会发送一个心跳。tickTime以毫秒为单位。
tickTime=2000
# The number of ticks that the initial
# synchronization phase can take
# initLimit：LF初始通信时限
# 集群中的follower服务器(F)与leader服务器(L)之间初始连接时能容忍的最多心跳数（tickTime的数量）。
initLimit=5
# The number of ticks that can pass between
# sending a request and getting an acknowledgement
# syncLimit：LF同步通信时限
# 集群中的follower服务器与leader服务器之间请求和应答之间能容忍的最多心跳数（tickTime的数量）。
syncLimit=2
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just
# example sakes.
# dataDir：数据文件目录
# Zookeeper保存数据的目录，默认情况下，Zookeeper将写数据的日志文件也保存在这个目录里。
dataDir=/data/soft/zookeeper-3.4.12/data
# dataLogDir：日志文件目录
# Zookeeper保存日志文件的目录。
dataLogDir=/data/soft/zookeeper-3.4.12/logs
# the port at which the clients will connect
# clientPort：客户端连接端口
# 客户端连接 Zookeeper 服务器的端口，Zookeeper 会监听这个端口，接受客户端的访问请求。
clientPort=2181
# the maximum number of client connections.
# increase this if you need to handle more clients
#maxClientCnxns=60
#
# Be sure to read the maintenance section of the
# administrator guide before turning on autopurge.
#
# http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_maintenance
#
# The number of snapshots to retain in dataDir 保留数量3
autopurge.snapRetainCount=3
# Purge task interval in hours
# Set to "0" to disable auto purge feature 清理时间间隔1小时
autopurge.purgeInterval=1
# 服务器名称与地址：集群信息（服务器编号，服务器地址，LF通信端口，选举端口）
# 这个配置项的书写格式比较特殊，规则如下：
# server.N=YYY:A:B
# 其中N表示服务器编号，YYY表示服务器的IP地址，A为LF通信端口，表示该服务器与集群中的leader交换的信息的端口。B为选举端口，表示选举新leader时服务器间相互通信的端口（当leader挂掉时，其余服务器会相互通信，选择出新的leader）。一般来说，集群中每个服务器的A端口都是一样，每个服务器的B端口也是一样。但是当所采用的为伪集群时，IP地址都一样，只能时A端口和B端口不一样。
启动
4、可以不修改zoo.cfg，默认配置就行，进去zookeeper安装目录，启动ZooKeeper
-
启动命令：./bin/zkServer.sh start -
停止命令：./bin/zkServer.sh stop -
重启命令：./bin/zkServer.sh restart -
状态查看命令：./bin/zkServer.sh status
伪集群模式
伪集群模式就是在同一主机启动多个zookeeper并组成集群
在同一台主机上，通过复制得到三个zookeeper实例
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对三个zookeeper节点进行配置
zookeeper1配置文件conf/zoo.cfg修改如下
zookeeper1配置文件conf/zoo.cfg修改如下：
注：server.1中的数字1为服务器的ID，需要与myid文件中的id一致，下一步将配置myid
tickTime=2000
initLimit=5
syncLimit=2
dataDir=/data/soft/zookeeper-cluster/zookeeper-3.4.12-12181/data
dataLogDir=/data/soft/zookeeper-cluster/zookeeper-3.4.12-12181/logs
clientPort=12181
server.1=127.0.0.1:12888:13888
server.2=127.0.0.1:14888:15888
server.3=127.0.0.1:16888:17888
注：server.1中的数字1为服务器的ID，需要与myid文件中的id一致，下一步将配置myid
zookeeper1的data/myid配置，使用如下命令（即新建一个文件data/myid，在其中添加内容为
echo '1' > data/myid
zookeeper2配置文件conf/zoo.cfg修改如下：
tickTime=2000
initLimit=5
syncLimit=2
dataDir=/data/soft/zookeeper-cluster/zookeeper-3.4.12-12183/data
dataLogDir=/data/soft/zookeeper-cluster/zookeeper-3.4.12-12183/logs
clientPort=12182
server.1=127.0.0.1:12888:13888
server.2=127.0.0.1:14888:15888
server.3=127.0.0.1:16888:17888
zookeeper2的data/myid配置，使用如下命令：
echo '2' > data/myid
zookeeper3配置文件conf/zoo.cfg修改如下：
tickTime=2000
initLimit=5
syncLimit=2
dataDir=/data/soft/zookeeper-cluster/zookeeper-3.4.12-12183/data
dataLogDir=/data/soft/zookeeper-cluster/zookeeper-3.4.12-12183/logs
clientPort=12183
server.1=127.0.0.1:12888:13888
server.2=127.0.0.1:14888:15888
server.3=127.0.0.1:16888:17888
zookeeper3的data/myid配置，使用如下命令：
echo '3' > data/myid
分别启动三个zookeeper节点
./usr/local/zookeeper1/bin/zkServer.sh start
./usr/local/zookeeper2/bin/zkServer.sh start
./usr/local/zookeeper3/bin/zkServer.sh start
查看节点状态
./usr/local/zookeeper1/bin/zkServer.sh status
./usr/local/zookeeper2/bin/zkServer.sh status
./usr/local/zookeeper3/bin/zkServer.sh status
集群模式
集群模式就是在不同主机上安装zookeeper然后组成集群的模式，可以参考伪集群模式安装
在三台机器上分别部署1个ZooKeeper实例
zookeeper配置文件conf/zoo.cfg，如下
tickTime=2000
initLimit=5
syncLimit=2
dataDir=/data/soft/zookeeper-3.4.12/data
dataLogDir=/data/soft/zookeeper-3.4.12/logs
clientPort=2181
server.1=127.0.0.1:2888:3888
server.2=127.0.0.2:2888:3888
server.3=127.0.0.3:2888:3888
zookeeper的data/myid配置，使用如下命令：
echo '1' > data/myid
当然zookeeper1 对应的是 1，zookeeper2 对应的是 2，zookeeper3 对应的是 3
分别启动三个zookeeper节点，即完成对ZooKeeper集群的安装
ZooKeeper简单操作
下面操作在zookeeper单机模式下完成的
使用客户端连接ZooKeeper服务
./usr/local/zookeeper/bin/zkCli.sh -server 127.0.0.1:2181
./bin/zkCli.sh默认连接到本地127.0.0.1:2181
[root@localhost /]# ./usr/local/zookeeper/bin/zkCli.sh -server 127.0.0.1:2181
Connecting to 127.0.0.1:2181
2021-08-07 19:24:33,897 [myid:] - INFO [main:Environment@109] - Client environment:zookeeper.version=3.5.8-f439ca583e70862c3068a1f2a7d4d068eec33315, built on 05/04/2020 15:07 GMT
2021-08-07 19:24:33,903 [myid:] - INFO [main:Environment@109] - Client environment:host.name=localhost
2021-08-07 19:24:33,903 [myid:] - INFO [main:Environment@109] - Client environment:java.version=1.8.0_144
2021-08-07 19:24:33,905 [myid:] - INFO [main:Environment@109] - Client environment:java.vendor=Oracle Corporation
2021-08-07 19:24:33,905 [myid:] - INFO [main:Environment@109] - Client environment:java.home=/usr/local/java/jdk1.8.0_144/jre
2021-08-07 19:24:33,905 [myid:] - INFO [main:Environment@109] - Client environment:java.class.path=/usr/local/zookeeper/bin/../zookeeper-server/target/classes:/usr/local/zookeeper/bin/../build/classes:/usr/local/zookeeper/bin/../zookeeper-server/target/lib/*.jar:/usr/local/zookeeper/bin/../build/lib/*.jar:/usr/local/zookeeper/bin/../lib/zookeeper-jute-3.5.8.jar:/usr/local/zookeeper/bin/../lib/zookeeper-3.5.8.jar:/usr/local/zookeeper/bin/../lib/slf4j-log4j12-1.7.25.jar:/usr/local/zookeeper/bin/../lib/slf4j-api-1.7.25.jar:/usr/local/zookeeper/bin/../lib/netty-transport-native-unix-common-4.1.48.Final.jar:/usr/local/zookeeper/bin/../lib/netty-transport-native-epoll-4.1.48.Final.jar:/usr/local/zookeeper/bin/../lib/netty-transport-4.1.48.Final.jar:/usr/local/zookeeper/bin/../lib/netty-resolver-4.1.48.Final.jar:/usr/local/zookeeper/bin/../lib/netty-handler-4.1.48.Final.jar:/usr/local/zookeeper/bin/../lib/netty-common-4.1.48.Final.jar:/usr/local/zookeeper/bin/../lib/netty-codec-4.1.48.Final.jar:/usr/local/zookeeper/bin/../lib/netty-buffer-4.1.48.Final.jar:/usr/local/zookeeper/bin/../lib/log4j-1.2.17.jar:/usr/local/zookeeper/bin/../lib/json-simple-1.1.1.jar:/usr/local/zookeeper/bin/../lib/jline-2.11.jar:/usr/local/zookeeper/bin/../lib/jetty-util-9.4.24.v20191120.jar:/usr/local/zookeeper/bin/../lib/jetty-servlet-9.4.24.v20191120.jar:/usr/local/zookeeper/bin/../lib/jetty-server-9.4.24.v20191120.jar:/usr/local/zookeeper/bin/../lib/jetty-security-9.4.24.v20191120.jar:/usr/local/zookeeper/bin/../lib/jetty-io-9.4.24.v20191120.jar:/usr/local/zookeeper/bin/../lib/jetty-http-9.4.24.v20191120.jar:/usr/local/zookeeper/bin/../lib/javax.servlet-api-3.1.0.jar:/usr/local/zookeeper/bin/../lib/jackson-databind-2.10.3.jar:/usr/local/zookeeper/bin/../lib/jackson-core-2.10.3.jar:/usr/local/zookeeper/bin/../lib/jackson-annotations-2.10.3.jar:/usr/local/zookeeper/bin/../lib/commons-cli-1.2.jar:/usr/local/zookeeper/bin/../lib/audience-annotations-0.5.0.jar:/usr/local/zookeeper/bin/../zookeeper-*.jar:/usr/local/zookeeper/bin/../zookeeper-server/src/main/resources/lib/*.jar:/usr/local/zookeeper/bin/../conf:.:/usr/local/java/jdk1.8.0_144/jre/lib/rt.jar:/usr/local/java/jdk1.8.0_144/lib/dt.jar:/usr/local/java/jdk1.8.0_144/lib/tools.jar
2021-08-07 19:24:33,906 [myid:] - INFO [main:Environment@109] - Client environment:java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
2021-08-07 19:24:33,906 [myid:] - INFO [main:Environment@109] - Client environment:java.io.tmpdir=/tmp
2021-08-07 19:24:33,906 [myid:] - INFO [main:Environment@109] - Client environment:java.compiler=<NA>
2021-08-07 19:24:33,906 [myid:] - INFO [main:Environment@109] - Client environment:os.name=Linux
2021-08-07 19:24:33,906 [myid:] - INFO [main:Environment@109] - Client environment:os.arch=amd64
2021-08-07 19:24:33,906 [myid:] - INFO [main:Environment@109] - Client environment:os.version=3.10.0-1160.el7.x86_64
2021-08-07 19:24:33,906 [myid:] - INFO [main:Environment@109] - Client environment:user.name=root
2021-08-07 19:24:33,906 [myid:] - INFO [main:Environment@109] - Client environment:user.home=/root
2021-08-07 19:24:33,906 [myid:] - INFO [main:Environment@109] - Client environment:user.dir=/
2021-08-07 19:24:33,906 [myid:] - INFO [main:Environment@109] - Client environment:os.memory.free=13MB
2021-08-07 19:24:33,909 [myid:] - INFO [main:Environment@109] - Client environment:os.memory.max=247MB
2021-08-07 19:24:33,909 [myid:] - INFO [main:Environment@109] - Client environment:os.memory.total=15MB
2021-08-07 19:24:33,918 [myid:] - INFO [main:ZooKeeper@868] - Initiating client connection, connectString=127.0.0.1:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@6996db8
2021-08-07 19:24:33,926 [myid:] - INFO [main:X509Util@79] - Setting -D jdk.tls.rejectClientInitiatedRenegotiation=true to disable client-initiated TLS renegotiation
2021-08-07 19:24:33,947 [myid:] - INFO [main:ClientCnxnSocket@237] - jute.maxbuffer value is 4194304 Bytes
2021-08-07 19:24:33,960 [myid:] - INFO [main:ClientCnxn@1653] - zookeeper.request.timeout value is 0. feature enabled=
2021-08-07 19:24:33,976 [myid:127.0.0.1:2181] - INFO [main-SendThread(127.0.0.1:2181):ClientCnxn$SendThread@1112] - Opening socket connection to server localhost/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error)
Welcome to ZooKeeper!
JLine support is enabled
2021-08-07 19:24:34,197 [myid:127.0.0.1:2181] - INFO [main-SendThread(127.0.0.1:2181):ClientCnxn$SendThread@959] - Socket connection established, initiating session, client: /127.0.0.1:48252, server: localhost/127.0.0.1:2181
2021-08-07 19:24:34,309 [myid:127.0.0.1:2181] - INFO [main-SendThread(127.0.0.1:2181):ClientCnxn$SendThread@1394] - Session establishment complete on server localhost/127.0.0.1:2181, sessionid = 0x100008e5f4a0000, negotiated timeout = 30000
WATCHER::
WatchedEvent state:SyncConnected type:None path:null
[zk: 127.0.0.1:2181(CONNECTED) 0]
使用 ls 命令来查看当前 ZooKeeper 中所包含的内容：
命令：ls /
[zk: 127.0.0.1:2181(CONNECTED) 1] ls /
[zookeeper]
创建了一个新的 znode 节点“ zk ”以及与它关联的字符串
命令：create /zk myData
[zk: 127.0.0.1:2181(CONNECTED) 2] create /zk myData
Created /zk
[zk: 127.0.0.1:2181(CONNECTED) 3] ls /
[zk, zookeeper]
获取znode节点“ zk ”
命令：get /zk
[zk: 127.0.0.1:2181(CONNECTED) 4] get /zk
myData
删除znode节点“ zk ”
命令：delete /zk
[zk: 127.0.0.1:2181(CONNECTED) 5] delete /zk
[zk: 127.0.0.1:2181(CONNECTED) 6]
退出客户端
命令quit
[zk: 127.0.0.1:2181(CONNECTED) 6] quit
WATCHER::
WatchedEvent state:Closed type:None path:null
2021-08-07 19:30:15,086 [myid:] - INFO [main:ZooKeeper@1422] - Session: 0x100008e5f4a0001 closed
2021-08-07 19:30:15,087 [myid:] - INFO [main-EventThread:ClientCnxn$EventThread@524] - EventThread shut down for session: 0x100008e5f4a0001
原文
【ZooKeeper】ZooKeeper安装及简单操作 - H__D - 博客园 (cnblogs.com)
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