安装kubeadm采用国内阿里云镜像源，安装kubelet、kubeadm、kubectl:

1.安装kubeadm之前

cat < /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
exclude=kube*
EOF
2.开始安装

yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

systemctl enable kubelet