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A Python framework for Nagios plug-in developers
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pynagioscheck is a Python framework for Nagios plug-in developers.

pynagioscheck strives to conform to the practices described in the Nagios Plug-in Development Guidelines and, more importantly, save valuable system administrator time.


Check examples/ for a jump start.

The long version:

  1. Subclass nagioscheck.NagiosCheck as YourCheck.

  2. Set YourCheck.version. I prefer the major.minor.patch format, but you can use whatever you like. Increment this version number with every revision to your check script.

  3. If your check script takes mandatory arguments, describe them in YourCheck.usage. Arguments are not the same as options. e.g.:

    YourCheck.usage = '[options] HOST PORT'
  4. From YourCheck.__init__(), invoke NagiosCheck.__init__(self) before you do anything else.

  5. Let NagiosCheck know about any optional arguments you might want to parse with NagiosCheck.add_option(). It makes the most sense to do this from inside YourCheck.__init__().

  6. Define a YourCheck.check() method that will implement your actual service check. This method takes two arguments:

    1. opts: An instance of optparse.Values.

      Suppose an option is registered with:

      self.add_option('H', 'host', 'host', 'Hostname or ...')

      then, if the user supplies a hostname with -H HOST or --host HOST at the command line, the option argument (HOST) will be available from inside the check() method as:

      host = getattr(opts, 'host')

      Option argument attributes will be None if the option was not supplied at the command line.

    2. args: A list of mandatory postitional arguments. This list should match the usage information in YourCheck.usage.

    YourCheck.check() must raise nagioscheck.Status as soon as the result of the service check is known. YourCheck.check() must not return. See the examples and source for details.

  7. With YourCheck defined, instantiate and make it go with:

    if __name__ == '__main__':

What you get for free

  • Output string formatting and exit statuses conform to Nagios plug-in development guidelines. You don't need to remember that exit status 2 is used to signal CRITICAL check status, or that there are twelve inches in a foot.

  • Routines that make it easier to report Nagios perfdata (performance data).

  • A handful of utility functions for common data mangling and presentation chores.

  • A way to clean up after yourself if your execution time limit expires. This feature may not work with older versions of the Nagios NRPE server:

    --- nagios-nrpe-2.12~/src/nrpe.c 2008-03-11 08:04:43.000000000 +1100
    +++ nagios-nrpe-2.12/src/nrpe.c 2011-05-11 23:01:06.182404333 +1000
    @@ -1467,6 +1467,7 @@
                            /* send termination signal to child process group */
    +                       sleep(5); /* or whatever */

    See NagiosCheck.expired() for details.

  • -v works out of the box. Supply it more than once for additional verbosity. There are four levels in total. You control what is output at each level with your arguments to nagioscheck.Status(). See the examples and source for details. Use -vvv to view a backtrace of your check script to the point where it raised NagiosCheck.Status:

    % check_redis -vvv
    CRITICAL: Error 61 connecting Connection refused.
      File "./check_redis", line 29, in check
        info =
      File "build/bdist.macosx-10.6-universal/egg/redis/", line 380, in info
        return self.execute_command('INFO')
  • -h and --help work out of the box.

  • --version works out of the box.

What you probably should get for free, but don't

  • Validation helpers.
  • Threshold helpers.


Saj Goonatilleke <>

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