FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
error execution phase preflight: unable to fetch the kubeadm-config ConfigMap: failed to get component configs: could not download the kubelet configuration from ConfigMap "kubelet-config": configmaps "kubelet-config" is forbidden: User "system:bootstrap:y89j06" cannot get resource "configmaps" in API group "" in the namespace "kube-system

出现原因：
           kubeadm和kubelet版本与集群不一致。

解决方法：
           卸载cri-tools和kubelet，并重新安装kubeadm和kubelet正确的版本，版本应依据master的版本来安装，不应高于master的版本。(如果kubelet版本高于kubeadm，则加入节点成功之后会一直处于NotReady状态）
————————————————

检查集群的版本：

[root@master01 kube-controller-manager]# kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"21", GitVersion:"v1.21.3", GitCommit:"ca643a4d1f7bfe34773c74f79527be4afd95bf39", GitTreeState:"clean", BuildDate:"2021-07-15T21:03:28Z", GoVersion:"go1.16.6", Compiler:"gc", Platform:"linux/amd64"}

node1:

[root@node1 ~]# yum list installed|grep kubeadm
kubeadm.x86_64                       1.25.2-0                       @kubernetes 

删除1.25这个版本的kubeadm

yum remove kubeadm

yum remove kubelet

再安装与集群同样的版本：

[root@node1 ~]# systemctl enable kubelet && systemctl start kubelet

检查kubelet状态：

[root@node1 ~]# systemctl status kubelet

[root@node1 ~]# 

最后再加入集群：

[root@node1 ~]# yum install kubeadm-1.21.3
确认已经安装：

[root@node2 ~]# yum list installed|grep kubeadm
kubeadm.x86_64                       1.21.3-0                       @kubernetes 

但加入集群又报错：[kubelet-check] It seems like the kubelet isn't running or healthy.
[kubelet-check] The HTTP call equal to 'curl -sSL http://localhost:10248/healthz' failed with error: Get "http://localhost:10248/healthz": dial tcp [::1]:10248: connect: connection refused.

[root@node1 etc]# tail -f /var/log/messages

failed to parse kubelet flag: unknown flag: --network-plugin

kube出现unknown flag: --network-plugin

这个问题是kubelet的版本与master节点不一致。

master节点和node节点修改统一：

修改：vi /etc/docker/daemon.json ，添加以下内容：

{
  "exec-opts": ["native.cgroupdriver=systemd"]
}

再重启Docker

[root@node1 etc]# systemctl stop docker.service
Warning: Stopping docker.service, but it can still be activated by:
  docker.socket
[root@node1 etc]# systemctl start docker.service

再来重新添加集群：

kubeadm join 192.168.10.11:6443 --token abcdef.0123456789abcdef \
        --discovery-token-ca-cert-hash sha256:171372e7f2cc19d81a2a390345dbf52e8508b868c9fbd4cae1e645f5bb9198e7