注：以下步驟兩臺機器上都要執行：
0、刪除podman
CentOS 8 內置了podman, 刪掉。
[root@master01 ~]# yum remove podman
1、使用國內（阿里）源：
[root@master01 ~]# yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
2、安裝Docker：
[root@master01 ~]# yum -y install docker-ce
可能會報錯：
[root@master01 ~]# yum -y install docker-ce
CentOS-8 - Base - mirrors.aliyun.com 14 kB/s | 3.8 kB 00:00
CentOS-8 - Extras - mirrors.aliyun.com 6.4 kB/s | 1.5 kB 00:00
CentOS-8 - AppStream - mirrors.aliyun.com 16 kB/s | 4.3 kB 00:00
Docker CE Stable - x86_64 40 kB/s | 22 kB 00:00
Error:
Problem: package docker-ce-3:19.03.8-3.el7.x86_64 requires containerd.io >= 1.2.2-3, but none of the providers can be installed
- cannot install the best candidate for the job
- package containerd.io-1.2.10-3.2.el7.x86_64 is excluded
- package containerd.io-1.2.13-3.1.el7.x86_64 is excluded
- package containerd.io-1.2.2-3.3.el7.x86_64 is excluded
- package containerd.io-1.2.2-3.el7.x86_64 is excluded
- package containerd.io-1.2.4-3.1.el7.x86_64 is excluded
- package containerd.io-1.2.5-3.1.el7.x86_64 is excluded
- package containerd.io-1.2.6-3.3.el7.x86_64 is excluded
(try to add '--skip-broken' to skip uninstallable packages or '--nobest' to use not only best candidate packages)
解決方案：手動下載並安裝軟件包：
[root@master01 temp]# wget https://download.docker.com/linux/centos/7/x86_64/edge/Packages/containerd.io-1.2.6-3.3.el7.x86_64.rpm
[root@master01 temp]# yum install containerd.io-1.2.6-3.3.el7.x86_64.rpm
再將安裝docker-ce即可。
3、配置iptables策略：
注：這是一個大坑，如不正確配置，會導致主機之間不能正常通信。
新版的docker在機器重啓時docker會自動設置FORWORD策略爲DROP。
修改 /lib/systemd/system/docker.service
在[Service]標籤下加入如下參數：
ExecStartPost=/sbin/iptables -P FORWARD ACCEPT
使配置生效：
systemctl daemon-reload
systemctl restart docker
最好重啓（reboot)
4、添加aliyun docker倉庫加速
[root@master01 ~]# mkdir -p /etc/docker
[root@master01 ~]# tee /etc/docker/daemon.json <<-'EOF'
{
"registry-mirrors": ["https://fl791z1h.mirror.aliyuncs.com"]
}
EOF
[root@master01 ~]# systemctl daemon-reload
[root@master01 ~]# systemctl restart docker