K8S通常执行如下语句进行初始化：
```
kubeadm init --config=kubeadm_config.yml --upload-certs
```
或者：
kubeadm init --config kubeadm.yaml
这两条语句的区别就是 第一条生成带certificate key 用来增加master节点的join操作
后一条就只生成了join work节点的从左。
```
在 kubeadm 初始话集群成功后会返回join 命令，里面有 token，discovery-token-ca-cert-hash等参数，都需要记下来。
token 和discovery-token-ca-cert-hash 可以通过以下指令查询“
* 在master节点执行kubeadm token list获取token（注意查看是否过期）
```
kubeadm token list
TOKEN TTL EXPIRES USAGES DESCRIPTION EXTRA GROUPS
47gqgy.6s6ixpaji7uvyexs 23h 2021-09-16T15:19:24+08:00 authentication,signing system:bootstrappers:kubeadm:default-node-token
abcdef.0123456789abcdef 20h 2021-09-16T11:33:48+08:00 authentication,signing system:bootstrappers:kubeadm:default-node-token
tih0zc.wya6ql0z8cu0o37g 1h 2021-09-15T17:17:10+08:00 Proxy for managing TTL for the kubeadm-certs secret
```
* 如果没有--discovery-token-ca-cert-hash值，通过以下命令获取
```
openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //'
d51efc3d524678c821fe1ca33e447b0b904b1dede6d7b1e203c7e045abe410dd
```
也可以重新生成：
* 执行kubeadm token create --print-join-command，重新生成 join 命令 可用来join work节点
```
kubeadm token create --print-join-command
W0915 15:19:24.536673 9028 configset.go:348] WARNING: kubeadm cannot validate component configs for API groups [kubelet.config.k8s.io kubeproxy.config.k8s.io]
kubeadm join 10.132.24.99:6443 --token 47gqgy.6s6ssxpaji7uvyexs --discovery-token-ca-cert-hash sha256:d51efc3d524678c821fsssca33e447b0b904b1dede6d7b1e203c7e045abe410dd
```
如果需要添加master节点需要
* 使用 kubeadm init phase upload-certs --upload-certs 重新生成certificate-key
（这里需要注意老版本 需要用 kubeadm init phase upload-certs --experimental-upload-certs 生成）
```
kubeadm init phase upload-certs --upload-certs
I0915 15:17:08.073342 7441 version.go:252] remote version is much newer: v1.22.1; falling back to: stable-1.19
W0915 15:17:10.611539 7441 configset.go:348] WARNING: kubeadm cannot validate component configs for API groups [kubelet.config.k8s.io kubeproxy.config.k8s.io]
[upload-certs] Storing the certificates in Secret "kubeadm-certs" in the "kube-system" Namespace
[upload-certs] Using certificate key:
6d7089e97b8c96ac7ad478173c7928e5becdf1faed85ccd2d4654b8dc514fc32
```
然后加 master 节点：用上面生成的 work join 命令和后面生成的生成的--certificate-key 值拼接起来执行
```
kubeadm join 10.136.17.12:6443 --token abcdef.0123456789abcdef \
--discovery-token-ca-cert-hash sha256:2fbacdf6a9473d5da1d98900f73cxxx772b12ac99017d6ae756d8c3cc \
--control-plane --certificate-key f0725584c26c192478d266c4dc5804a1ss5d7b40257837eea0676d1972cca
```
参考
https://blog.csdn.net/dazuiba008/article/details/94595451
