I see that a lot of docker images in the docker repository are made with an Ubuntu base.
What does that mean? Does each container bundle a stripped down version of the Linux kernel?
Do containers sit on top of their own kernels? But I thought containers share the kernel of the host (which in some cases is boot2docker, a custom Tiny Core Linux build, and in others something like CoreOS).
EDIT: Clarifying the question a bit. Yes I know docker is a process container, not a full VM. But since there are "Ubuntu" containers in the official docker hub registry and other OSes like CentOS, what does it mean to run Ubuntu in a container?
Answer: Ahh it just dawned on me. It is the Ubuntu user land processes, containing apt-get and other configuration processes for a particular Ubuntu build. Similarly for CentOS. Docker is not single process, just single entry. So for these distributions the entry point is some sort of init process that spawns other processes.