How to allow users to execute code on my SaaS product server-side?

As the title states, I'd like to allow my users to execute arbitrary code they write on our servers. Obviously, this has major security implications.

What would be the best approach as far as containerizing + sandboxing the execution runtime, such that they can execute code from various languages like Python, Node.js, etc. without something "escaping" into our EC2 instances for instance (pun intended)

Obviously, this has been done (many times) before, so I'm curious if any of you have experience with this sort of thing and the best implementation. Are there any libraries, frameworks, etc. out there already for something like this?