Imports k8s.io/client-go/tools/clientcmd/api k8s.io/client-go/util/cert k8s.io/kubernetes/cmd/kubeadm/app/constants k8s.io/kubernetes/cmd/kubeadm/app/phases/certs/pkiutil k8s.io/client-go/tools/clientcmd Standard library imports bytes crypto/rsa crypto/x509 fmt io/ioutil os path/filepath