How to check if ZooKeeper is running or up from command prompt?
HadoopConfigApache ZookeeperApache KafkaPsHadoop Problem Overview
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.
-
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??
-
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?
Hadoop Solutions
Solution 1 - Hadoop
To check if Zookeeper is accessible. One method is to simply telnet to the proper port and execute the stats command.
root@host:~# telnet localhost 2181
Trying 127.0.0.1...
Connected to myhost.
Escape character is '^]'.
stats
Zookeeper version: 3.4.3-cdh4.0.1--1, built on 06/28/2012 23:59 GMT
Clients:
Latency min/avg/max: 0/0/677
Received: 4684478
Sent: 4687034
Outstanding: 0
Zxid: 0xb00187dd0
Mode: leader
Node count: 127182
Connection closed by foreign host.
Solution 2 - Hadoop
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
Solution 3 - Hadoop
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.
Solution 4 - Hadoop
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
Solution 5 - Hadoop
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.
Solution 6 - Hadoop
enter the below command to verify if zookeeper is running :
echo "ruok" | nc localhost 2181 ; echo
expected response: imok
Solution 7 - Hadoop
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.
Solution 8 - Hadoop
From a Windows 10
- Open Command Promt then type
telnet localhost 2181
and then you typesrvr
OR - From inside bin folder, open a PowerShell window and type
zkServer.sh status
Solution 9 - Hadoop
I use:
jps
Depending on your installation a running Zookeeper would look like
HQuorumPeer
or sth. with zookeeper in it's name.
Solution 10 - Hadoop
For people who uses the official docker image:
https://hub.docker.com/_/zookeeper
in the whitelist is only enabled srvr
See below the example:
telnet hostname 2181
Trying ::1...
Connected to localhost.
Escape character is '^]'.
srvr
Zookeeper version: 3.7.0-e3704b390a6697bfdf4b0bef79e3da7a4f6bac4b, built on 2021-03-17 09:46 UTC
Latency min/avg/max: 0/0.0/0
Received: 3
Sent: 2
Connections: 1
Outstanding: 0
Zxid: 0x0
Mode: standalone
Node count: 5
Connection closed by foreign host.
Doc:
> ZOO_4LW_COMMANDS_WHITELIST > > Defaults to srvr. Zookeeper's 4lw.commands.whitelist > > A list of comma separated Four Letter Words commands that user wants to use. A valid Four Letter Words command must be put in this list else ZooKeeper server will not enable the command. By default the whitelist only contains "srvr" command which zkServer.sh uses. The rest of four letter word commands are disabled by default.