Answers for "add docker to root centos 7"

make docker sudo less

$ sudo groupadd docker
$ sudo usermod -aG docker $USER
$ newgrp docker

docker install in centos u7

sudo yum update
sudo yum install yum-utils device-mapper-persistent-data lvm2

sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
sudo yum install docker-ce -y
sudo systemctl start docker
sudo systemctl enable docker
sudo systemctl status docker
sudo docker -v