copy from:https://www.youtube.com/watch?v=pm55BUwQ0iE

# Prerequisites

- Kernel must be 3.10 at minimum

- For checking kernel version, use this command:

uname -r

# Add Docker‘s repository

- Create file docker.repo and save it in /etc/yum.repos.d/

sudo touch /etc/yum.repos.d/docker.repo

- Edit docker.repo and write this:

[dockerrepo]

name=Docker Repository

baseurl=https://yum.dockerproject.org/repo/main/centos/$releasever/

enabled=1

gpgcheck=1

gpgkey=https://yum.dockerproject.org/gpg

# Install Docker

sudo yum -y install docker-engine

# Starting Docker Service

sudo systemctl start docker.service

install docker on centos7