安装搭建ZooKeeper环境

ZooKeeper有三种安装模式：单机安装(standalone)、伪集群模式、集群模式：

• standalone模式：只在一台机器上安装ZooKeeper，并只启动一个ZooKeeper实例。
• 伪集群：在一台机器上开启多个ZooKeeper实例来模拟集群。通过加载不同配置文件，分配不同数据目录来实现这种模式。因为在同一机器上运行，所以机器宕机，整个ZooKeeper就挂了。基本上不会布置这样的ZooKeeper集群。
• 集群模式：在至少3台机器上安装ZooKeeper构成集群，只要故障节点数量在一定范围内就能保证ZooKeeper服务的可用性。

真正布置的基本上都是集群模式，standalone偶尔用来做些测试，它有单点故障，伪集群模式也有单点故障。

集群模式并非一定至少3台机器，但用2台机器比1台机器更危险，因为随便故障一台都无法满足"大多数"的要求，都会阻塞整个ZooKeeper服务。而2台机器的故障几率是1台机器的2倍。所以，也建议采用奇数台机器来部署ZooKeeper。

ZooKeeper下载：https://mirrors.tuna.tsinghua.edu.cn/apache/zookeeper/stable/

我下载的是3.4.14版本。

1.安装jdk

ZooKeeper运行在java环境下，所以需要先安装jdk，且要求版本高于1.6。

jdk下载：http://www.oracle.com/technetwork/java/javase/downloads/index.html

源码包安装jdk

[root@master ~]# tar xf jdk-8u191-linux-x64.tar.gz -C /usr/local/
[root@master ~]# cd /usr/local/
[root@master local]# ln -sv jdk1.8.0_191/ jdk
"jdk" -> "jdk1.8.0_191/"

配置环境变量：

[root@master local]# vi /etc/profile.d/jdk.sh
JAVA_HOME=/usr/local/jdk
PATH=$JAVA_HOME/bin:$PATH
export JAVA_HOME PATH

[root@master local]# chmod o+x /etc/profile.d/jdk.sh 
[root@master local]# /etc/profile.d/jdk.sh

查看java版本。

[root@master local]# ln -sv /usr/local/jdk1.8.0_191/jre/bin/java /usr/local/bin
"/usr/local/bin/java" -> "/usr/local/jdk1.8.0_191/jre/bin/java"
[root@master local]# java -version
java version "1.8.0_191"
Java(TM) SE Runtime Environment (build 1.8.0_191-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.191-b12, mixed mode)

StandAlone模式

standalone模式是在单机上安装ZooKeeper。

先解压zookeeper-3.4.14.tar.gz。

[root@master ~]# tar xf zookeeper-3.4.14.tar.gz 

再把它移到/usr/local/下方便管理。

[root@master ~]# mv zookeeper-3.4.14 /usr/local/zookeeper

在ZooKeeper的bin目录下提供了几个Windows和Linux下的脚本：

[root@master ~]# cd /usr/local/zookeeper
[root@master zookeeper]# ls bin
README.txt  zkCleanup.sh  zkCli.cmd  zkCli.sh  zkEnv.cmd  zkEnv.sh  zkServer.cmd  zkServer.sh  zkTxnLogToolkit.cmd  zkTxnLogToolkit.sh

• zkServer：用于启动、停止ZooKeeper，且能查看ZooKeeper状态。

zkServer.sh {start|start-foreground|stop|restart|status|upgrade|print-cmd}

• zkEnv：设置ZooKeeper启动、关闭时的环境变量。在其余的每个脚本中都引用了这个脚本。
• zkCleanup：清除ZooKeeper的事务日志和快照。
• zkCli：ZooKeeper的一个命令行客户端。

设置ZooKeeper的环境变量，这不是必须的，只是为了方便操作上面的几个脚本

[root@master zookeeper]# echo 'ZOOKEEPER_HOME=/usr/local/zookeeper' >/etc/profile.d/zk.sh
[root@master zookeeper]# echo 'PATH=$ZOOKEEPER_HOME/bin:$PATH' >> /etc/profile.d/zk.sh
[root@master zookeeper]# chmod +x /etc/profile.d/zk.sh
[root@master zookeeper]# source /etc/profile.d/zk.sh

把windows下的脚本删除：

[root@master zookeeper]# rm -rf /usr/local/zookeeper/bin/{*.cmd,README.txt}
[root@master zookeeper]# ls bin/
zkCleanup.sh  zkCli.sh  zkEnv.sh  zkServer.sh  zkTxnLogToolkit.sh

为了启动ZooKeeper，先提供一个配置文件。默认配置文件的路径为$ZOOKEEPER_HOME下的conf目录。在这个目录下，有几个文件：

[root@master zookeeper]# ls conf
configuration.xsl  log4j.properties  zoo_sample.cfg

• configuration.xsl：无视它。
• log4f.properties：是ZooKeeper的日志配置文件。
• zoo_sample.cfg：是ZooKeeper的示例配置文件。

zkServer.sh默认的配置文件名为zoo.cfg。所以，在conf目录下创建一个zoo.cfg。写入几个保证ZooKeeper能正常运行的配置项：

[root@master zookeeper]# cd conf/
[root@master conf]# vi zoo.cfg
tickTime=2000
dataDir=/usr/local/zookeeper/data1
clientPort=2181
~

其中：

• tickTime：ZooKeeper中很多配置项(如心跳时间、连接超时时间等)都要用到的时间单位，这里配置为2000毫秒，即2秒。
• dataDir：ZooKeeper实例的数据目录。
• clientPort：ZooKeeper向外提供服务的端口。

然后用zkServer.sh来启动ZooKeeper。

[root@master zookeeper]# zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED

也可以手动指定启动时读取的配置文件：

[root@master zookeeper]# zkServer.sh start 

查看ZooKeeper的运行状态：

[root@master zookeeper]# zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: standalone

可以看到运行模式是"standalone"。

ZooKeeper启动后，就可以向外提供ZooKeeper服务了。这里用ZooKeeper提供的命令行客户端去连接一下ZooKeeper做个简单的测试。

连接ZooKeeper实例：

[root@master zookeeper]# zkCli.sh -server localhost:2181
Connecting to localhost:2181
2020-03-05 19:18:53,299 [myid:] - INFO  [main:Environment@100] - Client environment:zookeeper.version=3.4.14-4c25d480e66aadd371de8bd2fd8da255ac140bcf, built on 03/06/2019 16:18 GMT
2020-03-05 19:18:53,317 [myid:] - INFO  [main:Environment@100] - Client environment:host.name=master
2020-03-05 19:18:53,318 [myid:] - INFO  [main:Environment@100] - Client environment:java.version=1.8.0_191
2020-03-05 19:18:53,332 [myid:] - INFO  [main:Environment@100] - Client environment:java.vendor=Oracle Corporation
2020-03-05 19:18:53,333 [myid:] - INFO  [main:Environment@100] - Client environment:java.home=/usr/local/jdk1.8.0_191/jre
2020-03-05 19:18:53,333 [myid:] - INFO  [main:Environment@100] - 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/slf4j-log4j12-1.7.25.jar:/usr/local/zookeeper/bin/../lib/slf4j-api-1.7.25.jar:/usr/local/zookeeper/bin/../lib/netty-3.10.6.Final.jar:/usr/local/zookeeper/bin/../lib/log4j-1.2.17.jar:/usr/local/zookeeper/bin/../lib/jline-0.9.94.jar:/usr/local/zookeeper/bin/../lib/audience-annotations-0.5.0.jar:/usr/local/zookeeper/bin/../zookeeper-3.4.14.jar:/usr/local/zookeeper/bin/../zookeeper-server/src/main/resources/lib/*.jar:/usr/local/zookeeper/bin/../conf:
2020-03-05 19:18:53,334 [myid:] - INFO  [main:Environment@100] - Client environment:java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
2020-03-05 19:18:53,335 [myid:] - INFO  [main:Environment@100] - Client environment:java.io.tmpdir=/tmp
2020-03-05 19:18:53,335 [myid:] - INFO  [main:Environment@100] - Client environment:java.compiler=<NA>
2020-03-05 19:18:53,335 [myid:] - INFO  [main:Environment@100] - Client environment:os.name=Linux
2020-03-05 19:18:53,336 [myid:] - INFO  [main:Environment@100] - Client environment:os.arch=amd64
2020-03-05 19:18:53,336 [myid:] - INFO  [main:Environment@100] - Client environment:os.version=3.10.0-693.el7.x86_64
2020-03-05 19:18:53,337 [myid:] - INFO  [main:Environment@100] - Client environment:user.name=root
2020-03-05 19:18:53,338 [myid:] - INFO  [main:Environment@100] - Client environment:user.home=/root
2020-03-05 19:18:53,338 [myid:] - INFO  [main:Environment@100] - Client environment:user.dir=/usr/local/zookeeper
2020-03-05 19:18:53,342 [myid:] - INFO  [main:ZooKeeper@442] - Initiating client connection, connectString=localhost:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@799f7e29
2020-03-05 19:18:53,392 [myid:] - INFO  [main-SendThread(localhost:2181):ClientCnxn$SendThread@1025] - 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
2020-03-05 19:18:53,725 [myid:] - INFO  [main-SendThread(localhost:2181):ClientCnxn$SendThread@879] - Socket connection established to localhost/127.0.0.1:2181, initiating session
2020-03-05 19:18:53,856 [myid:] - INFO  [main-SendThread(localhost:2181):ClientCnxn$SendThread@1299] - Session establishment complete on server localhost/127.0.0.1:2181, sessionid = 0x100002d7ab00000, negotiated timeout = 30000

WATCHER::

WatchedEvent state:SyncConnected type:None path:null
[zk: localhost:2181(CONNECTED) 0] 

例如，创建一个znode：

[zk: localhost:2181(CONNECTED) 0] create /zk_test mydata1
Created /zk_test
[zk: localhost:2181(CONNECTED) 1] ls /
[zookeeper, zk_test]
[zk: localhost:2181(CONNECTED) 2] quit
Quitting...
2020-03-05 19:24:42,992 [myid:] - INFO  [main:ZooKeeper@693] - Session: 0x100002d7ab00000 closed
2020-03-05 19:24:42,994 [myid:] - INFO  [main-EventThread:ClientCnxn$EventThread@522] - EventThread shut down for session: 0x100002d7ab00000

配置伪集群模式

ZooKeeper的伪集群模式是在一个服务器上运行多个ZooKeeper实例来模拟ZooKeeper集群。伪集群模式下，每个实例的配置文件不同、数据目录不同、端口不同。一般来说，ZooKeeper集群至少需要3个服务器节点。

这里，我配置3个实例的ZooKeeper伪集群，它们的数据目录分别为$ZOOKEEPER_HOME下的data1、data2和data3。因为稍后要向这些目录中写myid文件，所以先创建这3个目录：

mkdir /usr/local/zookeeper/data{1,2,3}

先提供3个实例的配置文件，分别为$ZOOKEEPER_HOME/conf/{zoo1.cfg,zoo2.cfg,zoo3.cfg}。

以下是zoo1.cfg内容，各配置项稍后解释。

[root@master ~]# cd /usr/local/zookeeper/conf/

[root@master conf]# vi zoo1.cfg
tickTime=2000
dataDir=/usr/local/zookeeper/data1
clientPort=2181
initLimit=5
syncLimit=2
server.1=localhost:2887:3887
server.2=localhost:2888:3888
server.3=localhost:2889:3889

[root@master conf]# vi zoo3.cfg
tickTime=2000
dataDir=/usr/local/zookeeper/data3
clientPort=2183
initLimit=5
syncLimit=2
server.1=localhost:2887:3887
server.2=localhost:2888:3888
server.3=localhost:2889:3889

[root@master conf]# vi zoo2.cfg
tickTime=2000
dataDir=/usr/local/zookeeper/data2
clientPort=2182
initLimit=5
syncLimit=2
server.1=localhost:2887:3887
server.2=localhost:2888:3888
server.3=localhost:2889:3889

上面的配置项中：

• initLimit：当非leader节点(即follower和observer)启动时，需要先从leader那里复制数据，以保证所有ZooKeeper节点数据都是同步的。这个选项设置非leader节点从启动到完成同步的超时时长，它以tickTime为时间单位，所以上面的超时时长为5*2=10秒。

  一般来说，ZooKeeper保存的都是协调数据，数据量并不大，所以多数时候可以忽略这个参数，如果待同步数据真的很大，可以考虑增加这个超时时间。

• syncLimit：follower和leader之间数据延迟的最大时间长度。例如，有个节点的更新操作缓慢，它的数据已经严重落后于leader，ZooKeeper就会将它从ZooKeeper集群中踢出去。ZooKeeper使用时间来度量follower和leader之间数据的延迟，这个选项的值依赖于tickTime，例如tickTime=2000,syncLimit=2表示follower比leader延迟了4秒。
• server.X=[hostname]:port_A:port_B：该选项用来指定ZooKeeper集群中的服务器节点。其中：
  • X：整数。是ZooKeeper中服务器的一个简单标识。这个数值需要和dataDir下的myid文件内容一致。在启动ZooKeeper集群中的每个实例时，需要读取数据目录中的myid文件，并将该文件中的数值和配置文件中的server.X做匹配，匹配到哪个就表示是哪个ZooKeeper服务器节点。
  • hostname：ZooKeeper服务器节点的地址。
  • port_A：这是第一个端口，用于Follower和Leader之间的数据同步和其它通信。
  • port_B：这是第二个端口，用于Leader选举过程中投票通信。

所以，分别在每个实例的dataDir下创建对应的myid文件。

[root@master conf]# echo 1 >/usr/local/zookeeper/data1/myid
[root@master conf]# echo 2 >/usr/local/zookeeper/data2/myid
[root@master conf]# echo 3 >/usr/local/zookeeper/data3/myid

然后启动这3个ZooKeeper实例。

[root@master conf]# zkServer.sh start /usr/local/zookeeper/conf/zoo1.cfg
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/conf/zoo1.cfg
Starting zookeeper ... STARTED
[root@master conf]# zkServer.sh start /usr/local/zookeeper/conf/zoo2.cfg
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/conf/zoo2.cfg
Starting zookeeper ... STARTED
[root@master conf]# zkServer.sh start /usr/local/zookeeper/conf/zoo3.cfg
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/conf/zoo3.cfg
Starting zookeeper ... STARTED

查看当前java进程列表：

[root@master conf]# /usr/local/jdk1.8.0_191/bin/jps -l
2805 org.apache.zookeeper.server.quorum.QuorumPeerMain
1192 org.apache.zookeeper.server.quorum.QuorumPeerMain
2840 org.apache.zookeeper.server.quorum.QuorumPeerMain
2921 sun.tools.jps.Jps

查看这3个实例之间的关系：zoo2.cfg被选为leader，其它是follower。

[root@master conf]# zkServer.sh status /usr/local/zookeeper/conf/zoo1.cfg
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/conf/zoo1.cfg
Mode: follower
[root@master conf]# zkServer.sh status /usr/local/zookeeper/conf/zoo2.cfg
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/conf/zoo2.cfg
Mode: leader
[root@master conf]# zkServer.sh status /usr/local/zookeeper/conf/zoo3.cfg
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/conf/zoo3.cfg
Mode: follower

可以用ZooKeeper提供的命令行客户端工具来测试，写入其中一个实例的数据，其它实例也能收到。

[root@master conf]# zkCli.sh -server localhost:2181 create /my_znode hello
Connecting to localhost:2181
2020-03-05 20:05:50,002 [myid:] - INFO [main:Environment@100] - Client environment:zookeeper.version=3.4.14-4c25d480e66aadd371de8bd2fd8da255ac140bcf, built on 03/06/2019 16:18 GMT
2020-03-05 20:05:50,005 [myid:] - INFO [main:Environment@100] - Client environment:host.name=master
2020-03-05 20:05:50,006 [myid:] - INFO [main:Environment@100] - Client environment:java.version=1.8.0_191
2020-03-05 20:05:50,008 [myid:] - INFO [main:Environment@100] - Client environment:java.vendor=Oracle Corporation
2020-03-05 20:05:50,008 [myid:] - INFO [main:Environment@100] - Client environment:java.home=/usr/local/jdk1.8.0_191/jre
2020-03-05 20:05:50,009 [myid:] - INFO [main:Environment@100] - 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/slf4j-log4j12-1.7.25.jar:/usr/local/zookeeper/bin/../lib/slf4j-api-1.7.25.jar:/usr/local/zookeeper/bin/../lib/netty-3.10.6.Final.jar:/usr/local/zookeeper/bin/../lib/log4j-1.2.17.jar:/usr/local/zookeeper/bin/../lib/jline-0.9.94.jar:/usr/local/zookeeper/bin/../lib/audience-annotations-0.5.0.jar:/usr/local/zookeeper/bin/../zookeeper-3.4.14.jar:/usr/local/zookeeper/bin/../zookeeper-server/src/main/resources/lib/*.jar:/usr/local/zookeeper/bin/../conf:
2020-03-05 20:05:50,009 [myid:] - INFO [main:Environment@100] - Client environment:java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
2020-03-05 20:05:50,009 [myid:] - INFO [main:Environment@100] - Client environment:java.io.tmpdir=/tmp
2020-03-05 20:05:50,009 [myid:] - INFO [main:Environment@100] - Client environment:java.compiler=<NA>
2020-03-05 20:05:50,009 [myid:] - INFO [main:Environment@100] - Client environment:os.name=Linux
2020-03-05 20:05:50,009 [myid:] - INFO [main:Environment@100] - Client environment:os.arch=amd64
2020-03-05 20:05:50,009 [myid:] - INFO [main:Environment@100] - Client environment:os.version=3.10.0-693.el7.x86_64
2020-03-05 20:05:50,009 [myid:] - INFO [main:Environment@100] - Client environment:user.name=root
2020-03-05 20:05:50,009 [myid:] - INFO [main:Environment@100] - Client environment:user.home=/root
2020-03-05 20:05:50,009 [myid:] - INFO [main:Environment@100] - Client environment:user.dir=/usr/local/zookeeper/conf
2020-03-05 20:05:50,011 [myid:] - INFO [main:ZooKeeper@442] - Initiating client connection, connectString=localhost:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@799f7e29
2020-03-05 20:05:50,061 [myid:] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1025] - Opening socket connection to server localhost/0:0:0:0:0:0:0:1:2181. Will not attempt to authenticate using SASL (unknown error)
2020-03-05 20:05:50,134 [myid:] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@879] - Socket connection established to localhost/0:0:0:0:0:0:0:1:2181, initiating session
2020-03-05 20:05:50,169 [myid:] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1299] - Session establishment complete on server localhost/0:0:0:0:0:0:0:1:2181, sessionid = 0x1000012cc0a0000, negotiated timeout = 30000

WATCHER::

WatchedEvent state:SyncConnected type:None path:null
Created /my_znode
[root@master conf]# zkCli.sh -server localhost:2182 ls /
Connecting to localhost:2182
2020-03-05 20:05:58,543 [myid:] - INFO [main:Environment@100] - Client environment:zookeeper.version=3.4.14-4c25d480e66aadd371de8bd2fd8da255ac140bcf, built on 03/06/2019 16:18 GMT
2020-03-05 20:05:58,549 [myid:] - INFO [main:Environment@100] - Client environment:host.name=master
2020-03-05 20:05:58,549 [myid:] - INFO [main:Environment@100] - Client environment:java.version=1.8.0_191
2020-03-05 20:05:58,554 [myid:] - INFO [main:Environment@100] - Client environment:java.vendor=Oracle Corporation
2020-03-05 20:05:58,554 [myid:] - INFO [main:Environment@100] - Client environment:java.home=/usr/local/jdk1.8.0_191/jre
2020-03-05 20:05:58,555 [myid:] - INFO [main:Environment@100] - 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/slf4j-log4j12-1.7.25.jar:/usr/local/zookeeper/bin/../lib/slf4j-api-1.7.25.jar:/usr/local/zookeeper/bin/../lib/netty-3.10.6.Final.jar:/usr/local/zookeeper/bin/../lib/log4j-1.2.17.jar:/usr/local/zookeeper/bin/../lib/jline-0.9.94.jar:/usr/local/zookeeper/bin/../lib/audience-annotations-0.5.0.jar:/usr/local/zookeeper/bin/../zookeeper-3.4.14.jar:/usr/local/zookeeper/bin/../zookeeper-server/src/main/resources/lib/*.jar:/usr/local/zookeeper/bin/../conf:
2020-03-05 20:05:58,555 [myid:] - INFO [main:Environment@100] - Client environment:java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
2020-03-05 20:05:58,555 [myid:] - INFO [main:Environment@100] - Client environment:java.io.tmpdir=/tmp
2020-03-05 20:05:58,555 [myid:] - INFO [main:Environment@100] - Client environment:java.compiler=<NA>
2020-03-05 20:05:58,555 [myid:] - INFO [main:Environment@100] - Client environment:os.name=Linux
2020-03-05 20:05:58,555 [myid:] - INFO [main:Environment@100] - Client environment:os.arch=amd64
2020-03-05 20:05:58,556 [myid:] - INFO [main:Environment@100] - Client environment:os.version=3.10.0-693.el7.x86_64
2020-03-05 20:05:58,556 [myid:] - INFO [main:Environment@100] - Client environment:user.name=root
2020-03-05 20:05:58,556 [myid:] - INFO [main:Environment@100] - Client environment:user.home=/root
2020-03-05 20:05:58,556 [myid:] - INFO [main:Environment@100] - Client environment:user.dir=/usr/local/zookeeper/conf
2020-03-05 20:05:58,559 [myid:] - INFO [main:ZooKeeper@442] - Initiating client connection, connectString=localhost:2182 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@799f7e29
2020-03-05 20:05:58,624 [myid:] - INFO [main-SendThread(localhost:2182):ClientCnxn$SendThread@1025] - Opening socket connection to server localhost/0:0:0:0:0:0:0:1:2182. Will not attempt to authenticate using SASL (unknown error)
2020-03-05 20:05:58,703 [myid:] - INFO [main-SendThread(localhost:2182):ClientCnxn$SendThread@879] - Socket connection established to localhost/0:0:0:0:0:0:0:1:2182, initiating session
2020-03-05 20:05:58,719 [myid:] - INFO [main-SendThread(localhost:2182):ClientCnxn$SendThread@1299] - Session establishment complete on server localhost/0:0:0:0:0:0:0:1:2182, sessionid = 0x2000012cc100000, negotiated timeout = 30000

WATCHER::

WatchedEvent state:SyncConnected type:None path:null
[my_znode, zookeeper]
[root@master conf]#

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