I have installed docker on centos 7. by running following commands,
curl -sSL https://get.docker.com/ | sh
systemctl enable docker && systemctl start do
You also need to install Docker Compose. See the manual. Here are the commands you need to execute
sudo curl -L "https://github.com/docker/compose/releases/download/1.26.0/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
sudo mv /usr/local/bin/docker-compose /usr/bin/docker-compose
sudo chmod +x /usr/bin/docker-compose