How to block IP addresses during a DDOS attack?

Question

iptables

Hello, I have a dedicated server in OVH hosting a game server. When L3-L4 attacks come on it, there are no problems, OVH filters everything perfectly, but when L7 attacks start, most of the traffic passes through. What does the attacks come from different IPs, lately I have blocked about 10 thousand different ones.
The question is, is there any way to automate this? So that in case of a potential attack, the system determines who the bot is and adds its IP to the blacklist.

Addition: game servers are hosted on the server

Answer 1

What is your service? If the web (http/https) is one thing, some specific application is another.