A simple template for writing Nagios plugin in Python

nagios_template.py

#! /usr/bin/env python

###############################################################################
# Nagios plugin template 
#
# Notes
# - The RHEL boxes I work on are currently limited to Python 2.6.6, hence the 
#   use of (deprecated) optparse. If I can ever get them all updated to 
#   Python 2.7 (or better yet, 3.3), I'll switch to argparse
# - This template runs in 2.6-3.3. Any changes made will need to be appropriate
#   to the Python distro you want to use
#
###############################################################################

__author__ = 'Your Name Here'
__version__= 0.1

from optparse import OptionParser, OptionGroup
import logging as log

## These will override any args passed to the script normally. Comment out after testing.
#testargs = '--help'
#testargs = '--version'
#testargs = '-vvv'

def main():
    """ Main plugin logic goes here """

    ## Parse command-line arguments
    args, args2 = parse_args()

    ## Uncomment to test logging levels against verbosity settings
    # log.debug('debug message')
    # log.info('info message')
    # log.warning('warning message')
    # log.error('error message')
    # log.critical('critical message')
    # log.fatal('fatal message')

    gtfo(0)


def parse_args():
    """ Parse command-line arguments """

    parser = OptionParser(usage='usage: %prog [-v|vv|vvv] [options]',
                          version='{0}: v.{1} by {2}'.format('%prog', __version__, __author__))

    ## Verbosity (want this first, so it's right after --help and --version)
    parser.add_option('-v', help='Set verbosity level',
                      action='count', default=0, dest='v')

    ## CLI arguments specific to this script
    group = OptionGroup(parser,'Plugin Options')
    group.add_option('-x', '--extra', help='Your option here',
                     default=None)
    
    ## Common CLI arguments
    #parser.add_option('-c', '--critical', help='Set the critical threshold. Default: %(default)s',
    #                  default=97, type=float, dest='crit', metavar='##')
    #parser.add_option('-w', '--warning', help='Set the warning threshold. Default: %(default)s',
    #                  default=95, type=float, dest='warn', metavar='##')
    
    parser.add_option_group(group)

    ## Try to parse based on the testargs variable. If it doesn't exist, use args
    try:
        args, args2 = parser.parse_args(testargs.split())
    except NameError:
        args, args2 = parser.parse_args()

    ## Set the logging level based on the -v arg
    log.getLogger().setLevel([log.ERROR, log.WARN, log.INFO, log.DEBUG][args.v])

    log.debug('Parsed arguments: {0}'.format(args))
    log.debug('Other  arguments: {0}'.format(args2))

    return args, args2

def gtfo(exitcode, message=''):
    """ Exit gracefully with exitcode and (optional) message """

    log.debug('Exiting with status {0}. Message: {1}'.format(exitcode, message))
    
    if message:
        print(message)
    exit(exitcode)

if __name__ == '__main__':
    ## Initialize logging before hitting main, in case we need extra debuggability
    log.basicConfig(level=log.DEBUG, format='%(asctime)s - %(funcName)s - %(levelname)s - %(message)s')
    main()