How do you communicate downtime to users?

Yesterday my app’s backend went down for almost an hour. The specifics of the issue aren’t important. I’m looking for advice on how to build a system to allow me to communicate downtime to my users.

I’m thinking of building a really simple separate service that I can manually toggle when the main backend is down and have the app check it when it’s having connectivity issues. This way the app can quickly know if it’s having issues because of a known issue, and display some sort of message to the user.

Obviously it has to be a completely separate service so it isn’t affected by the downtime of the main application.

Does this already exist? How do you do it in your own apps/services? Thanks for the help 🙏