Consider the following scenario:
There are three independent web applications A, B and C that require an apache server to be run on.
A linux server runs web application A and may act as a Docker host. It is required that the applications B and C are isolated from the linux server and each other. They are therefore realized as two Docker containers, initially created from the same image.
My question updates, and security updates in special.
Do the two Docker containers require a full OS installation image? Can they share the host's apache binary, so security updates of the host's apache could be propagated to the containers automatically?
If this doesn't work: Would I need to install updates for apache on both containers independently, or could I benefit from the fact, that they are based on the same image, and somehow simplify the update process?