What work does the process in container “gcr.io/google_containers/pause:0.8.0” do?

Question

I have known clearly about the usage of the docker option --net=container:NAME_or_ID, I also have read the source code of kubernetes about how to configure the

Answer 1

Quoting from What is the role of 'pause' container?:

The pause container is a container which holds the network namespace for the pod. It does nothing 'useful'. (It's actually just a little bit of assembly that goes to sleep and never wakes up)

This means that your 'apache' container can die, and come back to life, and all of the network setup will still be there. Normally if the last process in a network namespace dies the namespace would be destroyed and creating a new apache container would require creating all new network setup. With pause, you'll always have that one last thing in the namespace.