[hadoop] How to check if ZooKeeper is running or up from command prompt?

I exploring a few options to setup kafka and I knew that the Zookeeper has to be up and running to initiate a kafka.

I would like to know how can I find the below.

1) hostname and port for my zookeeper instance---I checked the zoo.cfg and I could only find the ClientPort not the hostname, will hostname be the hostname of my box??

2) To check if ZooKeeper is up and running---I tried to do a ps -ef | grep "zoo" I could not find anything. May be I am using a wrong key word to search??

Any help would be really appreciated?

echo stat | nc localhost 2181 | grep Mode
echo srvr | nc localhost 2181 | grep Mode #(From 3.3.0 onwards)

Above will work in whichever modes Zookeeper is running (standalone or embedded).

Another way

If zookeeper is running in standalone mode, its a JVM process. so -

jps | grep Quorum

will display list of jvm processes; something like this for zookeeper with process ID

HQuorumPeer

Go to bin directory of Zookeeper and type

./zkServer.sh status

For More info go through below link:

http://www.ibm.com/developerworks/library/bd-zookeeper/

Hope this could help you.

From a Windows 10

• Open Command Promt then type telnet localhost 2181and then you type srvr OR
• From inside bin folder, open a PowerShell window and type zkServer.sh status

One other way would be to use 4 letter commands to validate if zookeeper service is healthy or not

echo stat | nc <zookeeper ip> 2181
echo mntr | nc <zookeeper ip> 2181
echo isro  | nc <zookeeper ip> 2181

More details on the documentation link below https://zookeeper.apache.org/doc/r3.1.2/zookeeperAdmin.html#sc_zkCommands

I did some test:

When it's running:

$ /usr/lib/zookeeper/bin/zkServer.sh status
JMX enabled by default
Using config: /usr/lib/zookeeper/bin/../conf/zoo.cfg
Mode: follower

When it's stopped:

$ zkServer status                                                                                                                                
JMX enabled by default
Using config: /usr/local/etc/zookeeper/zoo.cfg
Error contacting service. It is probably not running.

I'm not running on the same machine, but you get the idea.

I use:

  jps

Depending on your installation a running Zookeeper would look like

  HQuorumPeer

or sth. with zookeeper in it's name.

enter the below command to verify if zookeeper is running :

echo "ruok" | nc localhost 2181 ; echo 

expected response: imok

Zookeeper is just a Java process and when you start a Zookeeper instance it runs a org.apache.zookeeper.server.quorum.QuorumPeerMain class. So you can check for a running Zookeeper like this:

jps -l | grep zookeeper

or even like this:

jps | grep Quorum

upd:

regarding this: will hostname be the hostname of my box?? - the answer is yes.