The following is a primer for setting up your Raspberry PI to use SNMP to monitor the CPU and the GPU temperature in Cacti and to monitor the undervoltage condition. The instructions below cover Raspbian 11. I am assuming you are familiar with SNMP.

Raspian

Create a file named /usr/local/sbin/cputemp

#!/bin/bash
cpu=$(</sys/class/thermal/thermal_zone0/temp)
echo print $cpu/1000 | /usr/bin/perl
echo

Create a file named  /usr/local/sbin/gputemp

#!/bin/bash
gpu=$(/usr/bin/vcgencmd measure_temp)
echo $gpu | /usr/bin/awk -F '=' {'print $2'} | /usr/bin/awk -F "'" {'print $1'}

Create a file named /usr/local/sbin/undervoltage

#!/bin/bash
# check and see if currently the power supply is undervoltage
uv=$(/usr/bin/vcgencmd get_throttled)
uvn=$(echo $uv | /usr/bin/awk -F '=' {'print $2'} )
if [ $((uvn & 0x1)) == 0 ];
    then
        echo "Voltage good"
        echo "0"
    else
        echo "Undervoltage now"
        echo 1
fi

Create a file named /usr/local/sbin/undervoltage-flag

#!/bin/bash
# check and see if the power supply was under voltage since last reboot
uv=$(/usr/bin/vcgencmd get_throttled)
uvn=$(echo $uv | /usr/bin/awk -F '=' {'print $2'} )
if [ $((uvn & 0x10000)) == 0 ];
    then
        echo "Voltage good"
        echo "0"
    else
        echo "Undervoltage flagged"
        echo 1
fi

 

Set the permissions on the above files

sudo chmod 775 /usr/local/sbin/cputemp
sudo chmod 775 /usr/local/sbin/gputemp
sudo chmod 775 /usr/local/sbin/undervoltage-flag
sudo chmod 775 /usr/local/sbin/undervoltage

Install snmp by:

sudo apt-get update
sudo apt-get install snmpd

edit the file /etc/snmp/snmpd.conf file and add the following lines to the end

extend cputemp /usr/local/sbin/cputemp
extend gputemp /usr/local/sbin/gputemp
extend gputemp /usr/local/sbin/undervoltage
extend gputemp /usr/local/sbin/undervoltage-flag
view systemonly included .1.3.6.1.4.1.8072.1.3.2

If you want to be able to monitor the network interfaces via snmp/cacti, add the following line

view systemonly included .1.3.6.1.2.1.2

If you want to be able to monitor the storage usage and memory via snmp/cacti add the following line

view systemonly included .1.3.6.1.2.1.25.2.3.1

find the line near the top of the file that reads

agentaddress 127.0.0.1,[::1]

change it to read

gentaddress udp:161,udp6:[]:161

and remove the “#” in front of it

find the lines:

rocommunity public default -V systemonly
rocommunity6 public default -V systemonly

replace the word “public” with different community string. Note the community string is case sensitive.

save your changes and execute

usermod -a -G video Debian-snmp 

systemctl enable --now snmpd.service

Testing the snmp using net-snmp-utils

replace “public” with your community string

[user@mymachine ~]$ snmpwalk -v 1 -c public my.pi.ip.address nsExtendOutLine
NET-SNMP-EXTEND-MIB::nsExtendOutLine."cputemp".1 = STRING: 49.388
NET-SNMP-EXTEND-MIB::nsExtendOutLine."gputemp".1 = STRING: 49.4
NET-SNMP-EXTEND-MIB::nsExtendOutLine."undervoltage".1 = STRING: Voltage good
NET-SNMP-EXTEND-MIB::nsExtendOutLine."undervoltage".2 = STRING: 0
NET-SNMP-EXTEND-MIB::nsExtendOutLine."undervoltage-flag".1 = STRING: Voltage good
NET-SNMP-EXTEND-MIB::nsExtendOutLine."undervoltage-flag".2 = STRING: 0
[user@mymachine ~]$

Depending on your snmp configuration you may get data from other points in the snmp besides the above two

Cacti Graph Template

Download this zip file, unzip it and import it into cacti, then you can quickly graph the CPU and GPU temperatures