Zookeeper connection error

Question

We have a standalone zookeeper setup on a dev machine. It works fine for every other dev machine except this one testdev machine.

We get this error over and over aga

Answer 1

I was able to start with zookeeper and kafka having 2 nodes each. I got the error because i had started zookeeper with ./zkServer.sh instead of the kafka wrapper bin/zookeeper-server-start.sh config/zookeeper.properties

Answer 2

Also check the local firewall, service firewalld status

If it's running, just stop it service firewalld stop

And then give it a try.

Answer 3

I start standalone instance in my machine, and encounter the same problem. Finally, I change from ip "127.0.0.1" to "localhost" and the problem is gone.

Answer 4

In my case, I config zoo.cfg like this:

server.1=host-1:2888:3888
server.2=host-2:2888:3888
server.3=host-3:2888:3888

But, in host-1, I config host-1 resolve to 127.0.0.1 in /etc/hosts:

127.0.0.1   localhost host-1

which may results other hosts can't communicate with it. Resolve host-1 to its real ip solved this problem.

Hope this can help.

Answer 5

This is a common issue if the Zookeeper server is not running or no longer running (i.e. it crashed after you started it).

So first, check that you have the Zookeeper server running. A simple way to check is grep the running processes:

# ps -ef | grep zookeeper

(run this a couple of times to see if the same process ID is still there. its possible it keep restarting with a new process ID. Alternatively you can use 'systemctl status zookeeper' if your Linux distro support systemd)

You should see the process running as a java process:

# ps -ef | grep zookeeper
root       492     0  0 00:01 pts/1    00:00:00 java -Dzookeeper.log.dir=. -Dzookeeper.root.logger=INFO,CONSOLE -cp /root/zookeeper-3.5.0-alpha/bin/../build/classes:/root/zookeeper-3.5.0-alpha/bin/../build/lib/*.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/slf4j-log4j12-1.7.5.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/slf4j-api-1.7.5.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/servlet-api-2.5-20081211.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/netty-3.7.0.Final.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/log4j-1.2.16.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/jline-2.11.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/jetty-util-6.1.26.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/jetty-6.1.26.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/javacc.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/jackson-mapper-asl-1.9.11.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/jackson-core-asl-1.9.11.jar:/root/zookeeper-3.5.0-alpha/bin/../lib/commons-cli-1.2.jar:/root/zookeeper-3.5.0-alpha/bin/../zookeeper-3.5.0-alpha.jar:/root/zookeeper-3.5.0-alpha/bin/../src/java/lib/*.jar:/root/zookeeper-3.5.0-alpha/bin/../conf: -Xmx1000m -Xmx1000m -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.local.only=false org.apache.zookeeper.server.quorum.QuorumPeerMain /root/zookeeper-3.5.0-alpha/bin/../conf/zoo.cfg

If its not there, then there's likely something in the zookeeper log file indicating the issue.

To find the zookeeper log file, you should first figure out where its configured for logging. In my case I have zookeeper installed under my root directory (not suggesting you install it there):

[root@centos6_zookeeper conf]# pwd
/root/zookeeper-3.5.0-alpha/conf

And you can find the log setting in this file:

[root@centos6_zookeeper conf]# grep "zookeeper.log" log4j.properties 
zookeeper.log.dir=/var/log
zookeeper.log.file=zookeeper.log
zookeeper.log.threshold=INFO
zookeeper.log.maxfilesize=256MB
zookeeper.log.maxbackupindex=20

So Zookeeper is configured to log under /var/log.

Then there's usually a zookeeper.log and/or zookeeper.out file which should indicate your startup error.