运行yum makecache生成缓存
eple源：
rpm -Uvh http://ftp.sjtu.edu.cn/fedora/epel/6/i386/epel-release-6-8.noarch.rpm
docker 安装：
You will need RHEL 6.5 or higher, with a RHEL 6 kernel version 2.6.32-431 or higher as this has specific kernel fixes to allow Docker to work.
CentOS 6.5已经是2.6.32-431内核了，所以最好安装这个版本。
yum -y install docker-io
升级：yum -y update docker-io
手动升级：
wget https://get.docker.io/builds/Linux/x86_64/docker-latest -O docker mv -f docker /usr/bin/docker
升级完成
启动：
service docker start
开机启动：
chkconfig docker on