现象：ftp客户端链接到vsftpd时遇到如下报错信息
500 OOPS: vsftpd: refusing to run with writable root inside chroot()
原因：
vsftpd2.3.5之后的版本增强了安全检查，执行了chroot()用户的主目录不能有写权限
但我又需要上传至该目录则
解决办法：
在vsftpd.conf添加allow_writeable_chroot=YES，并重启vsftpd
验证结果：
1. 现象：kubeadm init时遇到如下报错信息
[ERROR ImagePull]: failed to pull image k8s.gcr.io/kube-apiserver:v1.18.8: output: Error response from daemon: Get https://k8s.gcr.io/v2/: proxyconnect tcp: dial tcp 172.96.236.117:10080: connect: connection refused , error: exit status 1
原因：
https://k8s.gcr.io无法访问
解决办法：
执行kubeadm init时加入命令行参数--image-repository registry.aliyuncs.com/google_containers
2. 现象：kubeadm init时遇到如下报错信息
error execution phase preflight: [preflight] Some fatal errors occurred: [ERROR ImagePull]: failed to pull image registry.aliyuncs.com/google_containers/kube-apiserver:v1.18.8: output: Error response from daemon: Get https://registry.aliyuncs.com/v2/: proxyconnect tcp: dial tcp 172.96.236.117:10080: connect: connection refused , error: exit status 1
解决办法：
注释或者删掉 /usr/lib/systemd/system/docker.service文件如下两行配置
Environment="HTTPS_PROXY=http://www.ik8s.io:10080" Environment="NO_PROXY=127.0.0.0/8,192.168.1.0/16"
重载配置systemctl daemon-reload
3. 现象：kubeadm init时遇到如下报错信息
[ERROR ImagePull]: failed to pull image registry.aliyuncs.com/google_containers/kube-apiserver:v1.18.8: output: Error response from daemon: manifest for registry.aliyuncs.com/google_containers/kube-apiserver:v1.18.8 not found: manifest unknown: manifest unknown , error: exit status 1
原因：
kube-apiserver:v1.18.8 在镜像仓库中找不到
解决办法：
安装低版本的kube-apiserver
执行kubeadm init时加入命令行参数--kubernetes-version=v1.18.1
4. 现象：kubeadm join时遇到如下报错信息
I1012 00:33:59.290299 1675 token.go:221] [discovery] The cluster-info ConfigMap does not yet contain a JWS signature for token ID "93ad67", will try again
原因：
主节点token过期
解决办法：
k8smaster ~]# kubeadm token create
k8smaster ~]# kubeadm token list
k8snode2 ~]# kubeadm join 192.168.1.100:6443 --token 6y73wt.55ankma86c3b8gnk
