Tools and Recipes for ZooKeeper Monitoring
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UPDATE: This repository have been committed [1] to the ZooKeeper trunk as a contrib. You can find it under src/contrib/monitoring. Please use the ZooKeeper JIRA [2] to submit issues and feature requests. It's going to be a part of the upcoming 3.4.0 release. Thanks. 

[1] https://issues.apache.org/jira/browse/ZOOKEEPER-799
[2] https://issues.apache.org/jira/browse/ZOOKEEPER

How To Monitor
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A ZooKeeper cluster can be monitored in two ways:
 1. by using the 'mntr' 4letterword command
 2. by using JMX to query the MBeans 

This repo contains tools and recipes for monitoring ZooKeeper using the first method. 

Check the file JMX-RESOURCE for some links to resources that could help you monitor a ZooKeeper cluster using the JMX interface. 

Requirements
------------

ZooKeeper 3.4.0 or later or you can apply ZOOKEEPER-744 patch over the latest 3.3.x release.
The server should understand the 'mntr' 4letterword command. 

$ echo 'mntr' | nc localhost 2181
zk_version  3.4.0--1, built on 06/19/2010 15:07 GMT
zk_avg_latency  141
zk_max_latency  1788
zk_min_latency  0
zk_packets_received 385466
zk_packets_sent 435364
zk_outstanding_requests 0
zk_server_state follower
zk_znode_count  5
zk_watch_count  0
zk_ephemerals_count 0
zk_approximate_data_size    41
zk_open_file_descriptor_count   20
zk_max_file_descriptor_count    1024

Python 2.6 (maybe it works on previous version but it's not tested yet).

In a nutshell
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All you need is check_zookeeper.py It has no external dependencies. 


*** On Nagios call the script like this:

./check_zookeeper.py -o nagios -s "<server-or-list-of-servers>" -k <key> -w <warning> -c <critical>


*** On Cacti define a custom data input method using the script like this:

./check_zookeeper.py -o cacti -s "<list-of-servers>" -k <key> --leader

-- outputs a single value for the given key fetched from the cluster leader

OR 

./check_zookeeper.py -o cacti -s "<list-of-servers>" -k <key> 

-- outputs multiple values on for each cluster node
ex: localhost_2182:0  localhost_2183:0  localhost_2181:0  localhost_2184:0  localhost_2185:0

*** On Ganglia:

install the plugin found in the ganglia/ subfolder OR

./check_zookeeper.py -o ganglia -s "<current-zookeeper-node>"

it will use gmetric to send zookeeper node status data.


Check the subfolders for configuration details and samples for each platform.

ZooKeeper 4letterwords Commands
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http://hadoop.apache.org/zookeeper/docs/current/zookeeperAdmin.html#sc_zkCommands