在CentOS7上安装supermin：
$ sudo yum install -y supermin*
创建镜像：（以下命令需要使用root运行）
# supermin5 -v --prepare bash coreutils -o supermin.d
# supermin5 -v --build --format chroot supermin.d -o appliance.d
# echo 7 > appliance.d/etc/yum/vars/releasever
# tar --numeric-owner -cpf centos-7.tar -C appliance.d .
# cat centos-7.tar | docker import - kongxx/centos-7
查看镜像：
$ sudo docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
kongxx/centos-7 latest 8c8f006aac6b About a minute ago 167 MB
...
运行容器：
$ sudo docker run -i -t kongxx/centos-7 /bin/bash
bash-4.2# cat /etc/redhat-release
CentOS Linux release 7.2.1511 (Core)