Thursday, November 14, 2013

Using a Newport Electronics iTHX-SD with MRTG and external script

I recently purchased an iTHX-SD which I planned to use to monitor temperature and humidity measurements in my server and communications closet. I thought I would be able to query the device via snmp from an mrtg daemon running on one of my servers, so I could just add a chart to the several bandwidth monitoring charts created by mrtg. However, upon more careful reading, I discovered that, while the device does support some snmp queries, it doesn't support acquiring the temperature and humidity measurements via snmp.

I am sure someone else who is more fluent in bash and/or perl or other scripting language might be able to provide more elegant and robust methods, but I wasn't able to find anything on the internet related to using the iTHX-SD with mrtg and external scripts. I went ahead and developed my own version, which has been in operation for a couple of days with reasonable results.

The mrtg.cfg configuration for the ITHX-SD is as follows:

Target[ithxsd1_humidtemp]: `/data/usr/local/bin/get_ithxsd.sh`
MaxBytes[ithxsd1_humidtemp]: 100
WithPeak[ithxsd1_humidtemp]: wmy
Unscaled[ithxsd1_humidtemp]: dwmy
Title[ithxsd1_humidtemp]: ITHX-SD1
PageTop[ithxsd1_humidtemp]: <h1>ITHX-SD1</h1>
Options[ithxsd1_humidtemp]: gauge, nopercent, unknaszero
YLegend[ithxsd1_humidtemp]: RH(%),Temp(�F)
ShortLegend[ithxsd1_humidtemp]:
Colours[ithxsd1_humidtemp]: GREEN#00eb0c,BLUE#0000ff,GRAY#AAAAAA,VIOLET#ff00ff
Legend1[ithxsd1_humidtemp]: Humidity
Legend2[ithxsd1_humidtemp]: Temperature
Legend3[ithxsd1_humidtemp]: Peak Value of Humidity
Legend4[ithxsd1_humidtemp]: Peak Value of Temperature
LegendI[ithxsd1_humidtemp]: RH(%)
LegendO[ithxsd1_humidtemp]: Temp(�F)

The script get_ithxsd.sh is as follows:

#!/bin/bash
humidity=0
temperature=0
temptest=`{ echo "*SRTF"; sleep 0.2; } | telnet 10.1.4.61 2000 2> /dev/null | egrep "^[0-9]+\.[0-9]+"`
humtest=`{ echo "*SRH"; sleep 0.2; } | telnet 10.1.4.61 2000 2> /dev/null | egrep  "^[0-9]+\.[0-9]+"`
if [[ $humtest =~ [0-9]+\.[0-9]+ ]]
then
        humidity=$humtest
else
        humtest=`{ echo "*SRH"; sleep 0.2; } | telnet 10.1.4.61 2000 2> /dev/null | egrep  "^[0-9]+\.[0-9]+"`
        if [[ $humtest =~ [0-9]+\.[0-9]+ ]]
        then
                humidity=$humtest
        fi
fi
if [[ $temptest =~ [0-9]+\.[0-9]+ ]]
then
        temperature=$temptest
else
        temptest=`{ echo "*SRTF"; sleep 0.2; } | telnet 10.1.4.61 2000 2> /dev/null | egrep "^[0-9]+\.[0-9]+"`
        if [[ $temptest =~ [0-9]+\.[0-9]+ ]]
        then
                temperature=$temptest
        fi
 fi
echo $humidity
echo $temperature
echo 0
echo 0

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