Providing PRTG with external sensor data via HTTP-requests

This project is used to provide sensor data from a Raspberry Pi to a PRTG Monitoring System by sending those via HTTP-Requests. For this, to work we need a working Raspberry Pi, the DHT22 / DHT11 sensor and a 4.7kOhm Resistor. A breadboard and jumper wires are useful.

The later goal will be to provide the data more cost-effective by using the ESP8266 to read the sensors and make the HTTP-Requests.

Connecting the Sensor to the Raspberry Pi

Looking at the front of the front of the sensor:

• Connect the left pin of the sensor to 3.3V on the Raspberry Pi
• Use the resistor to connect the next pin of the sensor to 3.3V on the Raspberry Pi
• Connect the same pin to the GPIO pin 22 on the Raspberry Pi
• Connect the right pin of the sensor to GND on the Raspberry Pi

Creating the Sensor on the PRTG Server

We first need to create an HTTP Push Data Sensor via the PRTG web interface, or Enterprise Console. In the device-tree, you need to perform a right-click on "local probe" => "add a new device". Name the new device as you like (i.e. DC_Monitoring_pi) and proceed. Add new sensors to your device by performing a right click on it and "add new sensor".

Sensor Configuration

• Name => Monitored value (i.e. Temperature, Humidity)
• Port => The port on which the request will be received. For each monitored value, a new port is needed
• Request Method => "GET"
• Identification Token => Choose your own, or leave {__guid__} to get an automatically generated after the sensor is setup
• Incoming Request => "Discard request" if you don´t want to store the values in a file
• No Incoming Data => Choose what to do when no data is received
• Value Type => "Float"
• Scanning Interval => The script is set to send a value every 10 seconds, so a scanning interval less than 10 seconds could result in distorted data. You can change this in line 32 of the reading script.

Install Docker on the Raspberry Pi

Install using the get-docker script:

curl -sSL https://get.docker.com | sh

Add your user (pi) to the docker group:

sudo usermod -aG docker pi

Restart your Pi:

sudo reboot now

Start a test container:

docker run hello-world

Following output verifies you´ve installed Docker correctly:

Hello from Docker! This message shows that your installation appears to be working correctly [...]

Lastly, install docker-compose.

sudo apt-get install docker-compose

Edit the Python scripts to work in your environment

hum_reading.py / temp_reading.py

You will find the scripts under prtg-webhook/hum/ or prtg-webhook/temp/

Change line 9 to your sensor (DHT11 / DHT22)

sensor = Adafruit_DHT.DHT22

Change line 11 to your used GPIO-pin on the Raspberry Pi

pin = 22

Change line 22 to your PRTG magic URL

api_url = '<PRTG_SERVER_IP>:<PORT>/<TOKEN>?value='

Starting the container

In the hum or temp folder:

docker-compose up -d

or:

docker-compose -f <PATH_TO_COMPOSE_FILE> up -d

Stopping the container

In the hum or temp folder:

docker-compose down

or:

docker-compose -f <PATH_TO_COMPOSE_FILE> down

Further resources

The HTTP Push Data Sensor Manual: https://www.paessler.com/manuals/prtg/http_push_data_sensor The Adafruit Documentation for the DHT Sensors : https://learn.adafruit.com/dht/