docker的趋势是浩浩荡荡啊，下面是各个系统安装docker的脚本

#!/bin/bash
updateKernel(){
    rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
    rpm -Uvh http://www.elrepo.org/elrepo-release-6-8.el6.elrepo.noarch.rpm
    yum --enablerepo=elrepo-kernel install kernel-lt -y
    sed -i "s/default=1/default=0/g" /etc/grub.conf
    sed -i "s/default=1/default=0/g" /boot/grub/grub.conf
}

centos6InstallDocker(){
    kernalVersion=`uname -r | cut -d "." -f 1`
    if [ $kernalVersion  -lt 3 ];then
        updateKernel
    fi
    yum -y install epel-release
    yum -y install docker-io
    service docker start
    chkconfig docker on
    docker version
}

centos7InstallDocker(){
    yum remove docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate docker-selinux docker-engine-selinux docker-engine
    yum install -y yum-utils device-mapper-persistent-data lvm2
    yum-config-manager  --add-repo https://download.docker.com/linux/centos/docker-ce.repo
    yum install docker-ce -y
    systemctl start docker
    systemctl enable docker
    docker version
}

ubuntuInstallDocker(){
    sudo apt-get remove docker docker-engine docker.io containerd runc
    sudo apt-get update
    sudo apt-get install apt-transport-https ca-certificates curl software-properties-common -y
    curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
    sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
    sudo apt-get update
    sudo apt-get install docker-ce -y
    ## test docker
    sudo docker container run hello-world
}

centosVersion=`cat /etc/redhat-release | sed -r 's/.* ([0-9]+)\..*/\1/'`
if [ $centosVersion -eq 6 ];then
    centos6InstallDocker
elif [ $centosVersion -eq 7 ];then
    centos7InstallDocker
else
    echo "Your version is wrong , Plese check !!!"
    exit
fi