I am configuring Kubernetes cluster with 2 nodes in coreos as described in https://coreos.com/kubernetes/docs/latest/getting-started.html without flannel. Both
Well, to answer your first question I think you have to do a few things to resolve your problem.
First, run the command given in this link : kubernetes.io/docs/setup/independent/create-cluster-kubeadm/…
Complete with those commands :
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
This admin.conf should be known to kubectl so as to work properly.