From the comments, it looks like they aren't even using a database and storing data client side ("to be stateless" they say). I don't know what kind of applicat

From the comments, it looks like they aren't even using a database and storing data client side ("to be stateless" they say). I don't know what kind of application they are serving but that has a whole can of complications. They are trying to make money yet I assume they don't have accounts etc. That's a bit overkill. So, no database, a single web service, yeah you might not need docker or alike. Depending on their use case they might need high availability so a backup server with a failover would be nice of course, ideally kicking in automatically and doing the necessary notifications.