Run Different Linux OS in Docker Container?

Question

Have been trying to learn Docker and one thing that puzzles me is how a different flavour of Linux (to the host OS) actually runs in the Docker container.

If we assume m

Answer 1

The Ubuntu image running inside the Docker container runs in what is called the user space for that container. This image can make kernel system calls to the RedHat host OS kernel (as part of transferring control from user space to kernel space for some user operations). Since the core kernel is common technology, the system calls are expected to be compatible even when the call is made from an Ubuntu user space code to a Redhat kernel code. This compatibility make it possible to share the kernel across containers which may all have different base OS images.