Using a Raspberry Pi Zero WH, a temperature sensor, and some code, I created a device that would notify me every so often if the temps are below the set threshold.

Cold Snap: Temperature Reporting IoT Device

Once connected, run the Node program from within the root of the project:

$ node .

The optional CLI arguments are as follows:

1. Temperature threshold in Fahrenheit (default: 35 deg)
2. Sensor read frequency in milliseconds (default: 5 seconds)
3. Report frequency in milliseconds (default: 1 hour)

To have the program take a measurement every second and report the temperature every 10 seconds if the temperature is under 60 degrees, run the following:

$ node . 60 1000 10000

I recommend you follow along in the walkthrough if you plan on using these examples

In order for the Pi to register the temperature sensor connected to GPIO pin #4, sudo add this line at the end of /boot/config.txt of your Pi:

dtoverlay=w1-gpio

In order for ngrok to be run at boot time by systemd, you'll need to create an ngrok config:

authtoken: <add_your_token_here>
tunnels:
  ssh:
    proto: tcp
    addr: 22