Tonight I’ve completed two new plugins for Nagios (or op5 in my case). They’re used to check DS18B20 and DS2438, i.e. temperature and relative humidity sensors in a 1-wire network. Since I have my 1-wire network(s) connected to a 1-wire server from Embedded Data Systems I wrote the plugins to pull the data from this device. They both use XML parsing and retrieve the data from a file called details.xml on the 1-wire server.

The first plugin is for checking the humidity sensor.

#!/usr/bin/python
# coding: utf-8
#
# Check the humidity probes from a DS2438 sensor on EDS 1-wire server
#
# By Marcus Wilhelmsson
# marcus@nickebo.net
# http://www.nickebo.net
# Licence GPLv2
# Version 0.1

import string, sys, os, argparse, urllib2, xml
from xml.dom.minidom import parseString

# Parse arguments
parser = argparse.ArgumentParser(description='Check humidity probes on EDS 1-wire server')
parser.add_argument('-H', action="store", dest="hostname", help='1-wire server hostname')
parser.add_argument('-p', action="store", dest="probe", type=int, help='Probe number, starting with 0')
parser.add_argument('-w', action="store", dest="warn", type=int, help='Warning humidity')
parser.add_argument('-c', action="store", dest="crit", type=int, help='Critical humidity')
results = parser.parse_args()

# Store parsed arguments in variables and make sure they're not empty
warn = results.warn
crit = results.crit
probe = results.probe
if (warn == None or crit == None or probe == None):
  parser.print_help()
  raise SystemExit()
if (crit <= warn):
  print "Critical humidity can't be less or equal to warning humidity"
  parser.print_help()
  raise SystemExit()

#Connect to the 1-wire server and download details.xml
hostname = results.hostname
try:
        file = urllib2.urlopen('http://' + hostname + '/details.xml')
except:
  print "Could not connect to " + hostname
  raise SystemExit(3)

#Read the data from the XML file and close it
data = file.read()
file.close()

#Parse XML
try:
  dom = parseString(data)
  xmlTag = dom.getElementsByTagName('Humidity')[probe].toxml()
  sensor = float(xmlTag.replace('<Humidity Units="PercentRelativeHumidity">','').replace('</Humidity>',''))
except:
  print "Error reading 1-wire probe"
  raise SystemExit(3)

# Print status    
if (sensor < warn):
  print "OK: Humidity: " + str(sensor) + " %|Humidity=" + str(sensor) + "%;" + str(warn) + ";" + str(crit) + ";" + str(sensor-10) + ";" + str(sensor+10)
  raise SystemExit(0)
elif (sensor >= warn and sensor < crit):
  print "WARNING: Humidity: " + str(sensor) + " %|Humidity=" + str(sensor) + "%;" + str(warn) + ";" + str(crit) + ";" + str(sensor-10) + ";" + str(sensor+10)
  raise SystemExit(1)
else:
  print "CRITICAL: Humidity: " + str(sensor) + " %|Humidity=" + str(sensor) + "%;" + str(warn) + ";" + str(crit) + ";" + str(sensor-10) + ";" + str(sensor+10)
  raise SystemExit(2)

#!/usr/bin/python
# coding: utf-8
#
# Check the temperature probes on EDS 1-wire server
#
# By Marcus Wilhelmsson
# marcus@nickebo.net
# http://www.nickebo.net
# Licence GPLv2
# Version 0.1

import string, sys, os, argparse, urllib2, xml
from xml.dom.minidom import parseString

# Parse arguments
parser = argparse.ArgumentParser(description='Check temperature probes on EDS 1-wire server')
parser.add_argument('-H', action="store", dest="hostname", help='1-wire server hostname')
parser.add_argument('-p', action="store", dest="probe", type=int, help='Probe number, starting with 0')
parser.add_argument('-w', action="store", dest="warn", type=int, help='Warning temperature')
parser.add_argument('-c', action="store", dest="crit", type=int, help='Critical temperature')
results = parser.parse_args()

# Store parsed arguments in variables and make sure they're not empty
warn = results.warn
crit = results.crit
probe = results.probe
if (warn == None or crit == None or probe == None):
  parser.print_help()
  raise SystemExit()
if (crit <= warn):
  print "Critical temperature can't be less or equal to warning temperature"
  parser.print_help()
  raise SystemExit()

#Connect to the 1-wire server
hostname = results.hostname
try:
        file = urllib2.urlopen('http://' + hostname + '/details.xml')
except:
  print "Could not connect to " + hostname
  raise SystemExit(3)

#Read the XML file and close it
data = file.read()
file.close()

#Parse XML
try:
  dom = parseString(data)
  xmlTag = dom.getElementsByTagName('Temperature')[probe].toxml()
  sensor = float(xmlTag.replace('<Temperature Units="Centigrade">','').replace('</Temperature>',''))
except:
  print "Error reading 1-wire probe"
  raise SystemExit(3)

# Print status    
if (sensor < warn):
  print "OK: Temperature: " + str(sensor) + " C|Temperature=" + str(sensor) + ";" + str(warn) + ";" + str(crit) + ";" + str(warn-5) + ";" + str(crit+5)
  raise SystemExit(0)
elif (sensor >= warn and sensor < crit):
  print "WARNING: Temperature: " + str(sensor) + " C|Temperature=" + str(sensor) + ";" + str(warn) + ";" + str(crit) + ";" + str(warn-5) + ";" + str(crit+5)
  raise SystemExit(1)
else:
  print "CRITICAL: Temperature: " + str(sensor) + " C|Temperature=" + str(sensor) + ";" + str(warn) + ";" + str(crit) + ";" + str(warn-5) + ";" + str(crit+5)
  raise SystemExit(2)

I’ve sent both plugins to Nagios Exchange, hopefully they’ll be up there in a couple of days tops.