How to run multiple web applications on one VPS/VDS?

Question

Network administration

Good afternoon! I want to ask a question regarding a possible way to run several web applications on one VPS at the same time with storing a small database in addition. But here's how to implement it right away? Using, let's say, sub-domains or just different directories using one IP.
In this case, I need everything to be something like this:
Having a simple database for not very large data, I think to take mySql
API Bot + A small static site, and both on the ktor
framework In fact, these are the main points that I need. Since before that I only drove LAN, I have no idea how to do it, and how much RAM is required for stable operation.
Well, as an additional question, I would like to know in general whether it is possible in theory with the above one more site / application, but on a different framework to keep at the same time?
Well, if this is possible, then how adequate will such a solution be with the correct selection of vds characteristics?
Or would it be more logical to run such processes separately?

spoiler

Эту мысль я изначально считаю бредовой, но а что если API бот будет как-то вкручен в сайт, являясь какой-то его активной частью? Или все же это не до конца бред?

Answer 1

It looks like a different web server. Of course, placed in isolation.
The only thing: somewhere in the input there is a separation, for example, in nginx.
Configure nginx to send a request for processing to a different upstream based on the domain name (server tag in the configuration file).
Well, the application that received the request does not even suspect that it received it not from the client directly, but through nginx.
The only difference is that if the IP address of the client is important to you, then you need to forward it to upstream.
If the IP address of the client is not important to you, then the operation of several applications is no different from their operation in one.
PS:
Of course, applications will have different IP ports. Ports 80 (http) and 443 (https) will be handled exclusively by nginx.