CO₂ monitor

Setup & Example

Motivation

Some time ago an article about a low cost CO₂ monitor came to our attention. A colleague quickly adopted the python code to fit in our prometheus setup. Since humans are sensitive to temperature and CO₂ level, we were now able to optimize HVAC settings in our office (Well, we mainly complained to our facility management).

For numerous reasons I wanted to replace the python code with a static Go binary.

Hardware

• CO₂ meter: Can be found for around 70EUR/USD at amazon.com & amazon.de. Regardless of minor differences between both devices, both work.
• Some machine which can run the compiled Go binary, has USB and is reachable from your prometheus collector. A very first version of a raspberry pi is already sufficient.

Software

You need prometheus to collect the metrics.

It might make things easier when you set up an udev rule e.g.

$ cat /etc/udev/rules.d/99-hidraw-permissions.rules 
KERNEL=="hidraw*", SUBSYSTEM=="hidraw", MODE="0664", GROUP="plugdev"

Run & Collect

Help

$ ./co2monitor --help      
usage: co2monitor [<flags>] <device> [<listen-address>]

Flags:
  --help  Show context-sensitive help (also try --help-long and --help-man).

Args:
  <device>            CO2 Meter device, such as /dev/hidraw2
  [<listen-address>]  The address to listen on for HTTP requests.

Starting the meter export

$ ./co2monitor /dev/hidraw2
2018/01/18 13:09:31 Serving metrics at ':8080/metrics'
2018/01/18 13:09:31 Device '/dev/hidraw2' opened

Credit

Henryk Plötz & wooga