Whoa! So fun. You got me curious - I have a similar home controller which does simple functions. Not as cool an uptime (we had a power blip ), but it is still running Elixir 1.10.3 released April 25, 2020! (Maybe I should be ashamed of that). Truthfully left alone for so long that I had lost the SSH key on it, but had left Erlang distribution running and was able to get in with -remsh!

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I decided to a minimal write-up in case it’s useful to anyone else. The project really centers around 2 components:

• Sensing the state of the garage door (may not matter to some folks). I use a hall effect sensor + a magnet stuck to the side of the door so I can sense when the door is closed
• Triggering the garage door opener. This is really easy, most wall-mounted buttons just create a connection between two terminals on the side of the garage door opener, so we mimic this same thing by connecting a relay to those same terminals and we an just close the relay for 500ms to simulate pressing that button

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Then in my repo you can see that the nerves config is just starting a couple of GenServer’s to watch the input from the hall effect sensor and publish state changes to a NATS topic. Similarly it listens to a NATS topic and triggers the relay.

I have a little phoenix app that is running on fly.io that connects to those same nats topics. It uses OAuth with google and has just 2 email addresses allowlisted for which authenticated users are allowed to “click” the button which will trigger the NATS message back to the nerves device.

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I went with a hosted app since I wanted to be able to remotely monitor the door and I didn’t want to wait on WiFi connection before I could push the button from my car. But you could easily run NATS and Phoenix locally if you prefer that for privacy/simplicity reasons.

That’s awesome!

I’ve just started to put my Nerves devices to work for home automation. Homex is pretty nice for getting sensors out there. I need to try some switched and stuff as well which I guess you’d need for a garage door

Then again, if it ain’t broke …