http://kubernetes.io/docs/getting-started-guides/kubeadm/
kubernetes-docs-kubeadm#run-in-pods-started-by-kubelet"The master is the machine where the control plane components run, including etcd (the cluster database) and the API server (which the kubectl CLI communicates with). All of these components run in pods started by kubelet." kubernetes-docs-kubeadm#run-in-pods-started-by-kubelet