Communication between Raspberry Pis on different networks
I'm sorry if this isn't the place to ask this, I also asked over at [email protected].
So what I want to do is this: Two RasPis are at different locations. They're on different networks but have internet access. Pressing a button on one of the Pis turns on an LED over at the other Pi via GPIO. How can I make the communication work? My first thought was Telegram bots as I'm familiar with those for notifications but you can't have Telegram bots communicate with each other, sadly. Is there a good (and secure) solution to this? Preferably using Python code and without continuous costs like server hosting, etc?
For a simple one way communucation where latency is unimportant, you might leverage any number of free services with apis you can abuse. You could send a tweer, or nastodon message, You could have one just update a file with a timestamp as a github gist or on pastebin or something.
There are also free mqtt broker services.
Or you could put one on the public internet with ddns name and talk directly to it.
Or you could set up a VPN between them - is logmein still a thing? - and then talk to each other directly via that interface