Pre-requisites
- OpenJDK8
- Zookeeper
Install OpenJDK
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Make sure you have the right OpenJDK version
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It should display 1.8.0_111
Set JAVA_HOME
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Building Apache Zookeeper
Download and unzip the Zookeeper package from Official Apache archive in all machines that will be used for zookeeper quorum as shown below:
$ tar -xzvf zookeeper-3.4.12.tar.gz |
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
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Create zookeeper user
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Configure zookeeper
Now, Create the directory zookeeper
under /var/lib
folder which will serve as Zookeeper data directory and create another zookeeper
directory under /var/log
where all the Zookeeper logs will be captured. Both of the directory ownership need to be changed as zookeeper.
$ sudo mkdir /var/lib/zookeeper $ cd /var/lib $ sudo chown zookeeper:zookeeper zookeeper/ $ sudo mkdir /var/log/zookeeper $ cd /var/log $ sudo chown zookeeper:zookeeper zookeeper/ |
Edit the bashrc
for the zookeeper user via setting up the following Zookeeper environment variables.
$ export ZOO_LOG_DIR=/var/log/zookeeper |
Source the .bashrc in current login session:
$ source ~/.bashrc |
Create the server id for the ensemble. Each zookeeper server should have a unique number in the myid
file within the ensemble and should have a value between 1 and 255.
In Node1
$ sudo sh -c "echo '1' > /var/lib/zookeeper/myid" |
In Node2
$ sudo sh -c "echo '2' > /var/lib/zookeeper/myid" |
In Node3
$ sudo sh -c "echo '3' > /var/lib/zookeeper/myid" |
Now, go to the conf folder under the Zookeeper home directory (location of the Zookeeper directory after Archive has been unzipped/extracted).
$ cd /home/zookeeper/zookeeper-3.4.13/conf/ |
By default, a sample conf file with name zoo_sample.cfg
will be present in conf
directory. Make a copy of it with name zoo.cfg
as shown below, and edit new zoo.cfg
as described across all the nodes.
$ cp zoo_sample.cfg zoo.cfg |
Edit zoo.cfg and the below
$ vi zoo.cfg |
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Now, do the below changes in log4.properties
file as follows.
$ vi log4j.properties |
zookeeper.log.dir=/var/log/zookeeper zookeeper.tracelog.dir=/var/log/zookeeper log4j.rootLogger=INFO, CONSOLE, ROLLINGFILE |
After the configuration has been done in zoo.cfg
file in all three nodes, start zookeeper in all the nodes one by one, using following command:
$ /home/zookeeper/zookeeper-3.4.12/bin/zkServer.sh start |
Zookeeper Service Start on all the Nodes.
ZooKeeper JMX enabled by default |
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
In Zookeeper ensemble out of three servers, one will be in leader mode and other two will be in follower mode. You can check the status by running the following commands.
$ /home/zookeeper/zookeeper-3.4.13/bin/zkServer.sh status |
Zookeeper Service Status Check.
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 |
node2
ZooKeeper JMX enabled by default |
node3
ZooKeeper JMX enabled by default |
standalone
ZooKeeper JMX enabled by default |
$ echo stat | nc node1 2181 |
Lists brief details for the server and connected clients.
$ echo mntr | nc node1 2181 |
Zookeeper list of variables for cluster health monitoring.
$ echo srvr | nc localhost 2181 |
Lists full details for the Zookeeper server.
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-3.4.12/bin/zkCli.sh -server `hostname -f`:2181 |
Connect to Zookeeper data node and lists the contents.
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]