Error:
1.6.0 kubelet fails with error "misconfiguration: kubelet cgroup driver: "cgroupfs" is different from docker cgroup driver: "systemd"

Solution:
vi /etc/systemd/system/kubelet.service.d/10-kubeadm.conf
modify
KUBELET_CGROUP_ARGS=--cgroup-driver=systemd
to
KUBELET_CGROUP_ARGS=--cgroup-driver=cgroupfs