在线安装docker

1. yum 包更新到最新【可选】
   yum update

2. 安装需要的软件包，yum-util提供yum-config-manager功能，另外两个是devicemapper驱动依赖的
   yum install -y yum-utils device-mapper-persistent-data lvm2

3. 设置yum源
   yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

4. 将服务器上的软件包信息先在本地缓存,以提高搜索安装软件的速度【可选】
   (可使用 yum clean all 命令清除缓存)
   yum makecache fast

5. 安装 docker。-y 是自动选择 yes，不用再手动输入
   yum -y install docker-ce

6. 查看docker版本，验证是否安装成功
   docker -v

离线安装docker

1. 将安装包 docker-19.03.1.tgz 上传到 /usr/local 目录下

2. 解压
   tar -xvf docker-19.03.1.tgz

3. 解压出来是一个docker文件夹，将docker目录下的所有内容复制到 /usr/bin/ 目录下
   cp docker/* /usr/bin/

4. 将docker注册为服务
   vim /etc/systemd/system/docker.service
   内容如下：

[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

5. 为文件添加可执行权限
   chmod +x /etc/systemd/system/docker.service
6. 启动docker
   systemctl daemon-reload #重载unit配置文件
   systemctl start docker #启动Docker
   systemctl enable docker.service #设置开机自启，可选
7. 验证docker是否启动成功
   systemctl status docker #查看docker状态
   docker -v #查看docker版本

在线安装的卸载方法

1.查询docker安装过的包：
yum list installed | grep docker
2.删除安装包：（-y表示出现选择默认输入y，不用再手动输入）
yum -y remove 安装包名称
3.删除镜像/容器等
rm -rf /var/lib/docker