Lm-sensors in net-snmp

Readout of integrated motherboard sensors was already a topic here, for VIA Epia boards and for WD Mybook World Edition as well. Such data is good to have visualized, so plotting it using MRTG was discussed too. This tool and its fundamental, net-snmp was designed to visualize network traffic data, so for sensor readings, an external script had to be constructed, which was quite inconvenient.

There is however a better way, briefly mentioned by lm-sensors.org, for which net-snmp has to be installed from source (download here, install instructions here) and has to be configured with the following options:

~$: cd net-snmp

~$: ./configure --with-mib-modules="ucd-snmp/lmsensorsMib" --with-ldflags="-lsensors" 

~$: make

~$: sudo make install

If installation was successful, lm-sensor readouts can be accessed via snmp, the same way as if they were polled by the command-line sensors tool:

~#: sensors

coretemp-isa-0000
Adapter: ISA adapter
Core 0:      +33.0 °C  (high = +78.0 °C, crit = +100.0 °C) 

coretemp-isa-0001
Adapter: ISA adapter
Core 1:      +32.0 °C  (high = +78.0 °C, crit = +100.0 °C) 

~#: snmpwalk -v 2c -c public localhost Sensors

LM-SENSORS-MIB::lmTempSensorsIndex.1 = INTEGER: 1
LM-SENSORS-MIB::lmTempSensorsIndex.2 = INTEGER: 2
LM-SENSORS-MIB::lmTempSensorsDevice.1 = STRING: Core 0
LM-SENSORS-MIB::lmTempSensorsDevice.2 = STRING: Core 1
LM-SENSORS-MIB::lmTempSensorsValue.1 = Gauge32: 33000
LM-SENSORS-MIB::lmTempSensorsValue.2 = Gauge32: 32000

Sadly, only CPU core temperatures can be read out for ICH8/ICH9 chipsets at the moment, still it is now way easier to integrate lm-sensor readings to net-snmp based logging and plotting tools such as MRTG.