Get zookeeper cluster status

Question

Is there a cli or some command-line, that I can use to find the zookeeper cluster status. Basically I want to know how to member in cluster or which nodes is acting as a leader.

Any pointers will be helpful.

Saw this question in stackoverflow: https://stackoverflow.com/questions/16669104/how-to-get-current-zookeeper-clusters-member-server-list, but wasn't helpful

Solution

You can determine which node is acting as a leader by enter the following command:

echo stat | nc localhost 2181 | grep Mode

You will get the response if the node is acting as a leader:

Mode: leader

If it is a follower, you will see:

Mode: follower

Alternatively, you can use the zkServer.sh located in /opt/zookeeper/bin:

./zkServer.sh status

The output of which would be:

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

You can obtain even more information using:

echo mntr | nc localhost 2181

The output of which is:

zk_version      3.4.8--1, built on 02/06/2016 03:18 GMT
zk_avg_latency  0
zk_max_latency  0
zk_min_latency  0
zk_packets_received     7
zk_packets_sent 6
zk_num_alive_connections        2
zk_outstanding_requests 0
zk_server_state follower
zk_znode_count  357
zk_watch_count  0
zk_ephemerals_count     5
zk_approximate_data_size        846524
zk_open_file_descriptor_count   36
zk_max_file_descriptor_count    4096

If the node is a leader, you will also see:

zk_followers    5
zk_synced_followers     5
zk_pending_syncs        0

The following will not be present on Windows platforms:

zk_open_file_descriptor_count   43
zk_max_file_descriptor_count    4096

Using the information above, you can determine the health of your Zookeeper ensemble.