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Pre-requisites

• OpenJDK8
• Zookeeper

Install OpenJDK

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Edit the /etc/hosts file across all the nodes and add the ipaddress and hostname (nodenames). If the hostnames are not right, change them in /etc/hosts file

192.168.1.102 node1
192.168.1.103 node2
192.168.1.105 node3

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Edit zoo.cfg and the below

$ vim /home/zookeeper/zookeeper-3.4.13/conf/vi zoo.cfg

dataDir=/var/lib/zookeeper
server.1=node1:2888:3888
server.2=node2:2888:3888
server.3=node3:2888:3888

Now, do the below changes in log4.properties file as follows.

$ vim /home/zookeeper/zookeeper-3.4.13/conf/vi log4j.properties

zookeeper.log.dir=/var/log/zookeeper 

zookeeper.tracelog.dir=/var/log/zookeeper 

log4j.rootLogger=INFO, CONSOLE, ROLLINGFILE

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$ /home/zookeeper/zookeeper-3.4.1312/bin/zkServer.sh start

Zookeeper Service Start on all the Nodes.

ZooKeeper JMX enabled by default
Using config: /home/ganesh/zookeeper-3.4.12/bin/../conf/zoo.

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cfg
Starting zookeeper ... STARTED

The log file will be created in /var/log/zookeeper of zookeeper named zookeeper.log, tail the file to see logs for any errors.

$ tail -f /var/log/zookeeper/zookeeper.log

Verify the Zookeeper Cluster and Ensemble

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$ /home/zookeeper/zookeeper-3.4.13/bin/zkServer.sh status

Zookeeper Service Status Check.Image Removed

In Zookeeper ensemble If you have 3 nodes, out of them, one will be in leader mode and other two will be in follower mode. You can check the status by running the following commands. If you have just one then it will be standalone.

With three nodes:

node1

ZooKeeper JMX enabled by default
Using config: /home/zookeeper/zookeeper-3.4.12/bin/../conf/zoo.cfg
Mode: leader

node2

ZooKeeper JMX enabled by default
Using config: /home/zookeeper/zookeeper-3.4.12/bin/../conf/zoo.cfg
Mode: follower

node3

ZooKeeper JMX enabled by default
Using config: /home/zookeeper/zookeeper-3.4.12/bin/../conf/zoo.cfg
Mode: follower

standalone

ZooKeeper JMX enabled by default
Using config: /home/zookeeper/zookeeper-3.4.12/bin/../conf/zoo.cfg
Mode: standalone

$ echo stat | nc node1 2181

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Lists brief details for the server and connected clients.

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$ echo mntr | nc node1 2181

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Zookeeper list of variables for cluster health monitoring.

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$ echo srvr | nc localhost 2181

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Lists full details for the Zookeeper server.

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If you need to check and see the znode, you can connect by using the below command on any of the zookeeper node:

$ /home/zookeeper/zookeeper-3.4.1312/bin/zkCli.sh -server `hostname -f`:2181

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Connect to Zookeeper data node and lists the contents.

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ent:user.name=root
2019-02-18 02:26:36,822 [myid:] - INFO [main:Environment@100] - Client environm
ent:user.home=/root
2019-02-18 02:26:36,822 [myid:] - INFO [main:Environment@100] - Client environm
ent:user.dir=/home/ganesh
2019-02-18 02:26:36,823 [myid:] - INFO [main:ZooKeeper@441] - Initiating client
connection, connectString=:2181 sessionTimeout=30000 watcher=org.apache.zookeep
er.ZooKeeperMain$MyWatcher@4b9af9a9
Welcome to ZooKeeper!
2019-02-18 02:26:36,846 [myid:] - INFO [main-SendThread(localhost:2181):ClientC
nxn$SendThread@1028] - Opening socket connection to server localhost/127.0.0.1:2
181. Will not attempt to authenticate using SASL (unknown error)
JLine support is enabled
2019-02-18 02:26:36,927 [myid:] - INFO [main-SendThread(localhost:2181):ClientC
nxn$SendThread@878] - Socket connection established to localhost/127.0.0.1:2181,
initiating session
2019-02-18 02:26:36,948 [myid:] - INFO [main-SendThread(localhost:2181):ClientC
nxn$SendThread@1302] - Session establishment complete on server localhost/127.0.
0.1:2181, sessionid = 0x1000001cfe00002, negotiated timeout = 30000

WATCHER::

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