在内网环境下，一般不能联网能在线部署，这时候就需要以离线的方式安装docker。本节内容主要总结一下在CentOS 7.6环境中离线安装docker的步骤。
*组件 版本CentOS 7.6Docker*19.03.3

1. 下载docker安装包

官方地址：https://download.docker.com/linux/static/stable/x86_64/docker-19.03.9.tgz

2. 解压缩

tar -zxvf docker-19.03.9.tgz

3. 解压的docker文件夹全部移动至/usr/bin目录

cp -p docker/* /usr/bin

4. 将docker注册为系统服务

① 在/usr/lib/systemd/system/目录下，创建docker.service文件
② 编辑docker.service文件

vi /usr/lib/systemd/system/docker.service

[Unit]
Description=Docker Application Container Engine
Documentation=http://docs.docker.com
After=network.target docker.socket
[Service]
Type=notify
EnvironmentFile=-/run/flannel/docker
WorkingDirectory=/usr/local/bin
ExecStart=/usr/bin/dockerd \
                -H tcp://0.0.0.0:4243 \
                -H unix:///var/run/docker.sock \
                --selinux-enabled=false \
                --log-opt max-size=1g
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=on-failure
[Install]
WantedBy=multi-user.target

5. 重启生效

重启守护进程

systemctl daemon-reload

systemctl start docker

查看docker状态

systemctl status docker

** 设置开机启动**

#systemctl enable docker

docker version