NagiosCheck is a simple and efficient tool for building custom probes for the Nagios monitoring system. It alleviates the pain of parsing command line options, writing and formatting the check results according to the Nagios plugin API.

gem install nagios_check

• Provide a simple to use DSL for building your own probes.
• Parse command line options.
• Report status data to Nagios (handles exceptions as UNKNOWN status).
• Provide a Nagios like range description format for the WARNING and CRITICAL states.
• Provide a simple timeout functionality to be more Nagios friendly.
• Report performance data to Nagios.

NagiosCheck is a module. To use it, simply include it in a class and declare how the check should behave:

require "nagios_check"

class SimpleCheck
  include NagiosCheck

  on "--host HOST", "-H HOST", :mandatory
  on "--port PORT", "-P PORT", Integer, default: 8080

  enable_warning
  enable_critical
  enable_timeout

  def check
    time = do_some_check(options.host, options.port)
    store_value :duration, time
  end
end

SimpleCheck.new.run

The command can then be used by Nagios:

  ruby simple_check.rb -H my_host -P my_port -w 4 -c 8 -t 10

If the value returned by do_some_check is between 0 and 4 inclusive the result is OK. If it is greater than 4 and less than 8 inclusive the result is WARNING. If it is greater than 8 the result is CRITICAL. See Nagios Developer Guidelines for more details on how the arguments of -w and -c are interpreted.

If the check method lasts more than 10 seconds, it times out and the returned value is UNKNOWN.

An alternative shorter way of writting the above check would be:

def check
  time(value_name: 'duration' do
    do_some_check(options.host, options.port)
  end
end

Released under the MIT License. See the MIT-LICENSE file for further details.

Copyright 2011 Dominique Broeglin