Hey all, do you know a service that drops you a message (push notification, email, whatever) when a heartbeat signal was not given in a certain interval?

What I am thinking about is for a home automation use-case. You have a Raspberry Pi or any server running. Your home automation is functioning without the internet. However, you might have VPN installed to be able to connect from elsewhere to check what's going. I want to be informed by a service when my home is offline. The idea would be to install a cronjob that calls every 5 min. an API. The API checks that every 5 min. There is a call. When there are two calls missed, it pushes you a message.

Implementation wise this is quite simple and straight forward. But I believe sometimes you need to focus on your domain and don't need to reinvent the wheel. Any hints here?