Simple Polling with PERL

In the last chapter we looked at a simple PERL script that would get an OID and then nicely format the output. We can use this method to string several gets together and build more useful monitoring applications.

Lets look at a "full featured" application that uses a simple polling method using the CLI interface to snmpget:

#!/usr/local/bin/perl

$SNMP_GET_CMD = "snmpget -v1 -c public -Ovq -m PowerNet-MIB";
$SNMP_TARGET = "10.10.1.224";

chomp($model = `${SNMP_GET_CMD} ${SNMP_TARGET} PowerNet-MIB::upsBasicIdentModel.0`);
chomp($serial = `${SNMP_GET_CMD} ${SNMP_TARGET} PowerNet-MIB::upsAdvIdentSerialNumber.0`);
chomp($cap = `${SNMP_GET_CMD} ${SNMP_TARGET} PowerNet-MIB::upsAdvBatteryCapacity.0`);
chomp($temp = `${SNMP_GET_CMD} ${SNMP_TARGET} PowerNet-MIB::upsAdvBatteryTemperature.0`);
chomp($out_load = `${SNMP_GET_CMD} ${SNMP_TARGET} PowerNet-MIB::upsAdvOutputLoad.0`);
chomp($out_v = `${SNMP_GET_CMD} ${SNMP_TARGET} PowerNet-MIB::upsAdvOutputVoltage.0`);
chomp($out_f = `${SNMP_GET_CMD} ${SNMP_TARGET} PowerNet-MIB::upsAdvOutputFrequency.0`);
chomp($out_status = `${SNMP_GET_CMD} ${SNMP_TARGET} PowerNet-MIB::upsBasicOutputStatus.0`);

$model =~ s/\"//g;      # Ditch the quotes.
$serial =~ s/\"//g;

print <<END;
APC UPS                         ${SNMP_TARGET}
Model: ${model}         Serial No: ${serial}

Battery Capacity: ${cap}
Battery Temp(F): ${temp}

Output Status: ${out_status}
Output Load: ${out_load}
Output: ${out_v}VAC @ ${out_f}Hz
END

When we run that, we get a nice and pretty output with the data we want:

$ ./apc_status.pl
APC UPS                         10.10.1.224
Model: Silcon DP340E            Serial No: SE(removed)

Battery Capacity: 100   
Battery Temp(F): 32

Output Status: onLine
Output Load: 53
Output: 118VAC @ 60Hz

This method, while not particularly pretty of efficient, is very quick and easy to both write and debug making this approach useful in a pinch.