If you're using kubeadm (https://github.com/kubernetes/kubeadm) to bootstrap your Kubernetes cluster, unfortunately, at the time of writing, HA support is still in progress (v.1.10). The cluster is created as a single master with a single etcd configured. You'll have to back up etcd regularly to secure your data. Refer to the kubeadm limitations at the official Kubernetes website for more information (https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/#limitations).