流程：
所有节点操作：
1、关闭防火墙，配置hosts
2、关闭selinux
3、关闭swap
4、设置yum源
5、安装docker-ce
6、设置参数
7、安装相关软件包
所有节点操作
firewall-cmd --set-default-zone=trusted
setenforce 0
sed -i 's/SELINUX=enforceing/SELINUX=disabled/g' /etc/selinux/config
swapon -s
swapoff -a ; sed -i '/swap/d' /etc/fstab
rm -f /etc/yum.repos.d/k8s.repo
cat > /etc/yum.repos.d/kubernetes.repo <<EOF
[kubernetes]
name=Kubernetes
baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF
yum clean all ; yum makecache
yum list --showduplicates kubeadm --disableexcludes=kubernetes
yum -y install docker-ce
systemctl enable docker --now
mkdir -p /etc/docker
cat > /etc/docker/daemon.json <<EOF
{
"registry-mirrors": ["https://koea0c8l.mirror.aliyuncs.com"] }
EOF
systemctl daemon-reload
systemctl restart docker
cat > kubernetes.conf <<EOF
net.bridge.bridge-nf-call-iptables=1
net.bridge.bridge-nf-call-ip6tables=1
net.ipv4.ip_forward=1
EOF
cp kubernetes.conf /etc/sysctl.d/kubernetes.conf
sysctl -p /etc/sysctl.d/kubernetes.conf
modprobe br_netfilter
sysctl -p /etc/sysctl.d/kubernetes.conf
yum -y install kubelet-1.20.1-0 kubeadm-1.20.1-0 kubectl-1.20.1-0 --disableexcludes=kubernetes
#systemctl restart kubelet
systemctl enable kubelet
