yum install wget
wget http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
cp docker-ce.repo /etc/yum.repos.d/
yum list docker-ce --showduplicates
yum install --setopt=obsoletes=0 --downloadonly --downloaddir=/home/pkgs docker-ce-17.03.2.ce-1.el7.centos.x86_64
yum localinstall *.rpm