通过kubeadm初始化后，都会提供node加入的token:
You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
https://kubernetes.io/docs/concepts/cluster-administration/addons/
You can now join any number of machines by running the following on each node
as root:
kubeadm join 18.16.202.35:6443 --token zr8n5j.yfkanjio0lfsupc0 --discovery-token-ca-cert-hash sha256:380b775b7f9ea362d45e4400be92adc4f71d86793ba6aae091ddb53c489d218c
默认token的有效期为24小时，当过期之后，该token就不可用了。
解决方法如下：
-
重新生成新的token
[root@node1 flannel]# kubeadm token create
kiyfhw.xiacqbch8o8fa8qj
[root@node1 flannel]# kubeadm token list
TOKEN TTL EXPIRES USAGES DESCRIPTION EXTRA GROUPS
gvvqwk.hn56nlsgsv11mik6 <invalid> 2018-10-25T14:16:06+08:00 authentication,signing <none> system:bootstrappers:kubeadm:default-node-token
kiyfhw.xiacqbch8o8fa8qj 23h 2018-10-27T06:39:24+08:00 authentication,signing <none> system:bootstrappers:kubeadm:default-node-token -
获取ca证书
sha256编码hash值[root@node1 flannel]# openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //'
5417eb1b68bd4e7a4c82aded83abc55ec91bd601e45734d6aba85de8b1ebb057 -
节点加入集群
kubeadm join 18.16.202.35:6443 --token kiyfhw.xiacqbch8o8fa8qj --discovery-token-ca-cert-hash sha256:5417eb1b68bd4e7a4c82aded83abc55ec91bd601e45734d6aba85de8b1ebb057
几秒钟后，您应该注意到kubectl get nodes在主服务器上运行时输出中的此节点。
上面太繁琐，一步到位：
kubeadm token create --print-join-command
第二种方法：
# 第二种方法
token=$(kubeadm token generate)
kubeadm token create $token --print-join-command --ttl=0