报错
error execution phase preflight: couldn’t validate the identity of the API Server: abort connecting to API servers after timeout of 5m0s
原因：master节点的token过期了
解决：创建新的token
#得到token
>kubeadm token create
#得到discovery-token-ca-cert-hash
> openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //'
重新添加就可以join成功啦。
参考： https://blog.csdn.net/weixin_44723434/article/details/94583457
