cat > /etc/yum.repos.d/kubernetes.repo << EOF
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64 Kubernetes源设为阿里
gpgcheck=0：表示对从这个源下载的rpm包不进行校验
repo_gpgcheck=0：某些安全性配置文件会在 /etc/yum.conf 内全面启用 repo_gpgcheck，以便能检验软件库的中继数据的加密签署
如果gpgcheck设为1，会进行校验，就会报错如下，所以这里设为0
repomd.xml signature could not be verified for kubernetes
