Python script to check the cpu load, cpu temperature, free space, used memory, swap usage, voltage and system clock speed on a Raspberry Pi computer and publish the data to a MQTT server.

I wrote this so I can monitor my raspberries at home with home assistant. The script was written and tested on Python 2 but it should work fine on Python 3. The script if very light, it takes 3 seconds as there are 5 half second sleeps in the code - due to mqtt haveing problems if I shoot the messages with no delay.

Each value measured by the script is send via a separate message for easier craetion of home assistant sensors.

Example message topic:

masoko/rpi4/cpuload

first part (masoko) is the main topic configurable via the config.py file.
second part (pi4) is the host name of the raspberry which is automatically pulled by the script, so you don't have to configure it for each installation (in case you have many raspberries like me).
third part (cpuload) is the name of the value (these are all values published via MQTT - cpuload, cputemp, diskusage, voltage, sys_clock_speed).

Installation

If you don't have pip installed:

$ sudo apt install python-pip

Then install this module needed for the script:

$ pip install paho-mqtt

Copy rpi-cpu2mqtt.py and config.py.example to a folder of your choise (I am using /home/pi/scripts/ ) and rename config.py.example to config.py

Configuration

Populate the variables for MQTT host, user, password and main topic in config.py.

You can also choose what messages are send and what is the delay between them.

This is the default configuration:

group_messages = True 
sleep_time = 0.5
cpu_load = True
cpu_temp = True
used_space = True
voltage = True
sys_clock_speed = True
swap = False
memory = False

If the group_messages is set to true the script will send just one message containing all values (I still haven't made the sensor configuration for this - the one below is for separate messages only) The group message is in json and looks like this:

{'used_space': '25', 'sys_clock_speed': '1500', 'cpu_temp': '43.0', 'voltage': '0.8500', 'cpu_load': '1.25', 'memory': 'False', 'swap': 'False'}

Test the script.

$ /usr/bin/python /home/pi/scripts/rpi-cpu2mqtt.py

Once you test the script there will be no output if it run OK but you should get 5 messages via the configured MQTT server (the messages count depends on your configuration).

Create a cron entry like this (you might need to update the path in the cron entry below, depending on where you put the script files):

*/2 * * * * /usr/bin/python /home/pi/scripts/rpi-cpu2mqtt.py

Home Assistant Integration

Once you installed the script on your raspberry you need to create some sensors in home assistant.

This is the sensors configuration assuming your sensors are separated in sensors.yaml file.

  - platform: mqtt
    state_topic: "masoko/rpi4/cpuload"
    name: rpi 4 cpu load
    unit_of_measurement: "%"

  - platform: mqtt
    state_topic: "masoko/rpi4/cputemp"
    name: rpi 4 cpu temp
    unit_of_measurement: "°C"

  - platform: mqtt
    state_topic: "masoko/rpi4/diskusage"
    name: rpi 4 diskusage
    unit_of_measurement: "%"

  - platform: mqtt
    state_topic: "masoko/rpi4/voltage"
    name: rpi 4 voltage
    unit_of_measurement: "V"

  - platform: mqtt
    state_topic: "masoko/rpi4/sys_clock_speed"
    name: rpi 4 sys clock speed
    unit_of_measurement: "hz"

  - platform: mqtt
    state_topic: "masoko/rpi4/swap"
    name: rpi 4 swap
    unit_of_measurement: "%" 

  - platform: mqtt
    state_topic: "masoko/rpi4/memory"
    name: rpi 4 memory
    unit_of_measurement: "%"

Add this to your customize.yaml file to change the icons of the sensors.

sensor.rpi_4_voltage:
  friendly_name: rpi 4 voltage
  icon: mdi:flash
sensor.rpi4_cpu_load:
  friendly_name: rpi4 cpu load
  icon: mdi:chip
sensor.rpi4_diskusage:
  friendly_name: rpi4 diskusage
  icon: mdi:harddisk
sensor.rpi_4_sys_clock_speed:
  icon: mdi:clock
sensor.rpi4_cpu_temp:
  friendly_name: rpi4 cpu temperature
sensor.rpi_4_swap:
  icon: mdi:folder-swap
sensor.rpi_4_memory:
  icon: mdi:memory

After that you need to create entities list via the home assistant GUI. You can use this code or compose it via the GUI.

type: entities
title: Rapsberry Pi MQTT monitor
entities:
  - entity: sensor.rpi4_cpu_load
  - entity: sensor.rpi4_cpu_temp
  - entity: sensor.rpi4_diskusage
  - entity: sensor.rpi_4_voltage
  - entity: sensor.rpi_4_sys_clock_speed
  - entity: sensor.rpi_4_swap
  - entity: sensor.rpi_4_memory

To Do

make an option to send all values as one message
maybe add network trafic monitoring via some third party software (for now I can't find a way to do it without additinal software)