Relay on Pi control

Configuration
1

Hi,

I have a relay connected to a Raspberry Pi Zero, running Raspbian Lite. The relay is connected in parallel to my garage door button. I can SSH into the Pi Zero and execute a Python script, which will then open/close the garage door.
I’d like to be able to control this via Home Assistant.
What is the best way to achieve this? Should I be looking for a way to execute the Python script from within HA? If so, how would I do that?
Should I be controlling the relay via MQTT instead of a Python script? If so, what is the best way to do that?
Is there a better option?
Thanks.

2

Either of your ideas would work, but I think using your existing script would be easier.

To use your existing script, you would need to define a command line switch and have the command run do the ssh and the command as one line - ssh [email protected] -C your_command.py
You would also need to make sure you enabled passwordless login from your HA pi to the other pi.

Alterntively, you could modify your Python script to connect to a broker, subscribe to a topic, and wait for messages on that topic before performing the action. Most people use the eclipse paho library and there are examples there on how to do this.

3

Thank you. I’m not sure how I do either of those things you suggested, but I will have a crack at it when I get home from work.

4

I’ve set up passwordless login. If I ssh into the Pi running Home Assistant, I can issue the command: ssh [email protected] python relay.py
where 1.2.3.4 is the ip address of the Pi zero and relay.py is the script that activates the relay, and it works like a charm. However, I cannot get it to work from within Home Assistant.
My config file looks like this:

  • platform: command_line
    switches:
    garage_door:
    command_on: ssh [email protected] -C python relay.py
    command_off: ssh pi(at)1.2.2.4 python relay.py

I’ve tried it with and without the -C, with and without quotation marks.
I have also enabled root ssh login and tried command_on: ssh root(at)1.2.2.4 python /home/pi/relay.py
No dice.
Any suggestions?