How do you choose the right sized EC2 instances/MongoDB clusters?

I am creating an API framework on Node.js/Express that's pretty simple - it has some features to interface with a MongoDB database cluster, e.g. there are APIs to create/update entries in the database. There are some frontends that will interface with this API framework. This app must handle 2000 users each making around 50 API calls per day, and a peak of let's say 800 users interacting with the app at the same time.My problem is that I have no idea what minimum specs I need for my database cluster and server I should use in my scenario. Or even, the best way to test my server these user connections won't go kaput on day one. How should I go about this?

Submitted July 22, 2020 at 08:58PM by AwareProgrammer