有一个Centos7的虚拟机，想要安装个docker测试一些docker用法和熟悉命令

一，准备工作

1，使用uname -r命令检查系统内核版本，只有大于3.10才建议安装Docker

2，使用yum update命令更新系统

如果该命令执行报错，类似cannot find a valid baseurl for repo:base/7/x86_64
那就需要更改仓库配置文件了，位置路径如下所示

/etc/yum.repos.d/CentOS-Base.repo

文件完整内容如下，采用了阿里云镜像

# CentOS-Base.repo  
#  
# The mirror system uses the connecting IP address of the client and the  
# update status of each mirror to pick mirrors that are updated to and  
# geographically close to the client.  You should use this for CentOS updates  
# unless you are manually picking other mirrors.  
#  
# If the mirrorlist= does not work for you, as a fall back you can try the  
# remarked out baseurl= line instead.  
#  
#  [base]  
name=CentOS-$releasever - Base - mirrors.aliyun.com  
failovermethod=priority  
baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/  http://mirrors.aliyuncs.com/centos/$releasever/os/$basearch/  http://mirrors.cloud.aliyuncs.com/centos/$releasever/os/$basearch/  
gpgcheck=1  
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7  #released updates  
[updates]  
name=CentOS-$releasever - Updates - mirrors.aliyun.com  
failovermethod=priority  
baseurl=http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/  http://mirrors.aliyuncs.com/centos/$releasever/updates/$basearch/  http://mirrors.cloud.aliyuncs.com/centos/$releasever/updates/$basearch/  
gpgcheck=1  
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7  #additional packages that may be useful  
[extras]  
name=CentOS-$releasever - Extras - mirrors.aliyun.com  
failovermethod=priority  
baseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/  http://mirrors.aliyuncs.com/centos/$releasever/extras/$basearch/  http://mirrors.cloud.aliyuncs.com/centos/$releasever/extras/$basearch/  
gpgcheck=1  
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7  #additional packages that extend functionality of existing packages  
[centosplus]  
name=CentOS-$releasever - Plus - mirrors.aliyun.com  
failovermethod=priority  
baseurl=http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/  http://mirrors.aliyuncs.com/centos/$releasever/centosplus/$basearch/  http://mirrors.cloud.aliyuncs.com/centos/$releasever/centosplus/$basearch/  
gpgcheck=1  
enabled=0  
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7  #contrib - packages by Centos Users  
[contrib]  
name=CentOS-$releasever - Contrib - mirrors.aliyun.com  
failovermethod=priority  
baseurl=http://mirrors.aliyun.com/centos/$releasever/contrib/$basearch/  http://mirrors.aliyuncs.com/centos/$releasever/contrib/$basearch/  http://mirrors.cloud.aliyuncs.com/centos/$releasever/contrib/$basearch/  
gpgcheck=1  
enabled=0  
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

PS：在CentOS环境的Vi编辑器一般模式下，按下yy（yank yank的缩写，意为复制），按下nyy（n为你想要复制的行数），按下p键，复制的文本将被粘贴到光标所在行的下一行。按v进入可视模式，按i进入编辑模式

二、安装Docker

1，安装必要软件包，三个Docker运行所需的依赖包

sudo yum install -y yum-utils device-mapper-persistent-data lvm2

2，设置Docker镜像源，设置成阿里的镜像源是为了加快安装和后续镜像的下载速度

sudo yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

3，安装最新版本的Docker CE，这一步可能要耗费一点时间

sudo yum install -y docker-ce docker-ce-cli containerd.io

三、启动Docker

sudo systemctl start docker 启动服务

sudo systemctl status docker 检查 Docker 服务的状态

sudo systemctl enable docker 开机自启

四、验证Docker

docker -v
docker --version

运行hello-world

sudo docker run hello-world

访问不了docker hub，所以无法运行hello-world，只能运行自己打包的镜像，就是把打包的jar包用docker生成镜像后在运行

五、使用Docker

具体使用参考以前一篇博文 Docker使用心得与技巧

六，卸载Docker

sudo yum remove docker docker-common docker-selinux docker-engine