# Create a folder for our new root structure
$ export centos_root='/centos_image/rootfs'
$ mkdir -p $centos_root
# initialize rpm database
$ rpm --root $centos_root --initdb
# download and install the centos-release package, it contains our repository sources
$ yum reinstall --downloadonly --downloaddir . centos-release
$ rpm --root $centos_root -ivh centos-release*.rpm
$ rpm --root $centos_root --import  $centos_root/etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
# install yum without docs and install only the english language files during the process
$ yum -y --installroot=$centos_root --setopt=tsflags='nodocs' --setopt=override_install_langs=en_US.utf8 install yum
# configure yum to avoid installing of docs and other language files than english generally
$ sed -i "/distroverpkg=centos-release/a override_install_langs=en_US.utf8\ntsflags=nodocs" $centos_root/etc/yum.conf
# chroot to the environment and install some additional tools
$ cp /etc/resolv.conf $centos_root/etc
$ chroot $centos_root /bin/bash <<EOF
yum install -y procps-ng iputils
yum clean all
EOF
$ rm -f $centos_root/etc/resolv.conf

# install and enable docker
$ yum install -y docker
...
$ systemctl start docker
# create docker image
$ tar -C $centos_root -c . | docker import - centos
sha256:28843acfa85226385d2db0196db72465729db38088ea98751d4a5c3d4c85ccd
$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
centos              latest              28843acfa852        11 seconds ago      287.7 MB
# run docker image
$ docker run --rm centos cat /etc/redhat-release
CentOS Linux release 7.2.1511 (Core)

Source: https://www.sidorenko.io/post/2016/07/creating-container-base-image-of-centos/