错误信息如下：
#kubeadm join 192.168.198.192:6443 --token mbj1ya.yu1775v2lbfloatr \
> --discovery-token-ca-cert-hash sha256:3a0e23f786ab39f6cc6311a7a9f4ef81eb38a55497bcfcbe32af83e227faec54
--discovery-token-ca-cert-hash sha256:3a0e23f786ab39f6cc6311a7a9f4ef81eb38a55497bcfcbe32af83e227faec54
W0221 12:12:21.982827 13058 join.go:346] [preflight] WARNING: JoinControlPane.controlPlane settings will be ignored when control-plane flag is not set.
[preflight] Running pre-flight checks
[WARNING IsDockerSystemdCheck]: detected "cgroupfs " as the Docker cgroup driver. The recommended driver is "systemd ". Please follow the guide at https://kubernetes.io/docs/setup/cri/
error execution phase preflight: [preflight] Some fatal errors occurred:
[ERROR DirAvailable--etc-kubernetes-manifests]: /etc/kubernetes/manifests is not empty
[ERROR FileAvailable--etc-kubernetes-kubelet.conf]: /etc/kubernetes/kubelet.conf already exists
[ERROR Port-10250]: Port 10250 is in use
[ERROR FileAvailable--etc-kubernetes-pki-ca.crt]: /etc/kubernetes/pki/ca.crt already exists
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`
To see the stack trace of this error execute with --v=5 or higher
解决办法：
在节点上先执行如下命令，清理kubeadm的操作，然后再重新执行join 命令：
#kubeadm reset
