一、安裝環境
目標服務器系統：RHEL7.4，Docker離線安裝包版本：20.10.12
二、安裝
1、解壓上傳的壓縮包，解壓后當前路徑會生成一個docker目錄：
tar -zxf docker-20.10.12.tgz
2、將docker服務注冊為service
cp docker/* /usr/bin/
vim /etc/systemd/system/docker.service
將如下內容粘貼到docker.service后保存退出；
ps：需要root權限，如果權限被限制，可以通過ln -s 軟連接指到 /etc/systemd/system/docker.service
[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
After=network-online.target firewalld.service
Wants=network-online.target
[Service]
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
ExecStart=/usr/bin/dockerd
ExecReload=/bin/kill -s HUP $MAINPID
# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity
# Uncomment TasksMax if your systemd version supports it.
# Only systemd 226 and above support this version.
#TasksMax=infinity
TimeoutStartSec=0
# set delegate yes so that systemd does not reset the cgroups of docker containers
Delegate=yes
# kill only the docker process, not all processes in the cgroup
KillMode=process
# restart the docker process if it exits prematurely
Restart=on-failure
StartLimitBurst=3
StartLimitInterval=60s
[Install]
WantedBy=multi-user.target
4、啟動
chmod +x /etc/systemd/system/docker.service #添加文件權限並啟動docker
systemctl daemon-reload #重載unit配置文件
systemctl start docker #啟動Docker
systemctl enable docker.service #設置開機自啟
5、驗證
systemctl status docker #查看Docker狀態
6、在另一台Docker服務器上導出鏡像：
#鏡像備份
docker save imagename -o /home/路徑/鏡像名.tar
7、在目標服務器導入鏡像：
#還原鏡像
# docker load --input 鏡像名.tar