anchor/nagios-plugin-mongodb

A Nagios plugin to check the status of MongoDB

Nagios-MongoDB

Overview

This is a simple Nagios check script to monitor your MongoDB server(s).

Installation

In your Nagios plugins directory run

git clone git://github.com/mzupan/nagios-plugin-mongodb.git

Usage

Install in Nagios

Edit your commands.cfg and add the following

define command {
    command_name    check_mongodb
    command_line    $USER1$/nagios-plugin-mongodb/check_mongodb.py -H $HOSTADDRESS$ -A $ARG1$ -W $ARG2$ -C $ARG3$
}

Then you can reference it like the following. This is is my services.cfg

Check Connection

This will check each host that is listed in the Mongo Servers group. It will issue a warning if the connection to the server takes 2 seconds and a critical error if it takes over 4 seconds

define service {
    use                 generic-service
    hostgroup_name          Mongo Servers
    service_description     Mongo Connect Check
    check_command           check_mongodb!connect!2!4
}   

Check Percentage of Open Connections

This is a test that will check the percentage of free connections left on the Mongo server. In the following example it will send out an warning if the connection pool is 70% used and a critical error if it is 80% used.

define service {
    use                 generic-service
    hostgroup_name          Mongo Servers
    service_description     Mongo Free Connections
    check_command           check_mongodb!connections!70!80
}   

Check Replication Lag

This is a test that will test the replication lag of Mongo servers. It will send out a warning if the lag is over 2 seconds and a critical error if its over 5 seconds

define service {
    use                 generic-service
    hostgroup_name          Mongo Servers
    service_description     Mongo Replication Lag
    check_command           check_mongodb!replication_lag!2!5
}

Check Memory Usage

This is a test that will test the memory usage of Mongo server. In my example my Mongo servers have 32 gigs of memory so I'll trigger a warning if Mongo uses over 20 gigs of ram and a error if Mongo uses over 28 gigs of memory.

define service {
    use                 generic-service
    hostgroup_name          Mongo Servers
    service_description     Mongo Memory Usage
    check_command           check_mongodb!memory!20!28
}

Check Lock Time Percentage

This is a test that will test the lock time percentage of Mongo server. In my example my Mongo I want to be warned if the lock time is above 5% and get an error if it's above 10%. When you start to have lock time it generally means your db is now overloaded.

define service {
    use                 generic-service
    hostgroup_name          Mongo Servers
    service_description     Mongo Lock Percentage
    check_command           check_mongodb!lock!5!10
}

Check Average Flush Time

This is a test that will check the average flush time of Mongo server. In my example my Mongo I want to be warned if the average flush time is above 100ms and get an error if it's above 200ms. When you start to get a high average flush time it means your database is write bound.

define service {
    use                 generic-service
    hostgroup_name          Mongo Servers
    service_description     Mongo Flush Average
    check_command           check_mongodb!flushing!100!200
}

Check status of mongodb

This is a test taht will check the status of nodes within a replset. Depending which status it is it sends a waring during status 0, 3 and 5, critical if the status is 4, 6 or 8 and a ok with status 1, 2 and 7.

define service {
      use                     generic-service
      host_name               Mongo Servers
      service_description     MongoDB state
      check_command           check_mongodb!replset_state!27017
}