Creating a docker Base Image - linux

Question

I have a private Linux distribution (based on redhat7).
I have an ISO file which holds the installation of that distribution, which can be used to install the OS on a clear system only.
I have some programs I would like to run as images on docker, each program on a different image.
Each program can only run on my Linux environment and so I am looking for a way to create the appropriate images, so they can be ran under docker.
I tried following Solomon instructions here:
mkdir rootfs
mount -o loop /path/to/iso rootfs
tar -C rootfs -c . | docker import - rich/mybase
But I don't know how to proceed. I can't run any command since the machine isn't running yet (no /bin/bash/ etc.)
How can I open the installation shell?
Is there a better way to run programs via docker on a private Linux distribution?
(Just to be clear, the programs can run only on that specific OS and that OS can only be installed on a clear machine. Not sure if I need a base image but I'd like to run these programs with Docker and that is possible only over this OS)
I ran into many questions like mine (like this) but I couldn't find answer that helped me.

Answer 1

Assumption
Server A where the ISO will be mount
Server R your private repositoy
Server N where container will be run
All server can connect to server R.
How to
build a base image as mentioned in your OP (named base/myimage)
Push the image to your private repository https://docs.docker.com/registry/deploying/
Create application images from your base base/myimage then push them to your private repo
From Server N, run the application image
docker run application/myapp

Answer 2

This script is from the official Docker contrib repo. It's used to create CentOS images from scratch. It should work with any Redhat/Centos based system and gives you plenty of control over the various steps. Anything beyond that you can then modify post-base-image through a Dockerfile.
The file is here
#!/usr/bin/env bash
#
# Create a base CentOS Docker image.
#
# This script is useful on systems with yum installed (e.g., building
# a CentOS image on CentOS). See contrib/mkimage-rinse.sh for a way
# to build CentOS images on other systems.
usage() {
cat <<EOOPTS
$(basename $0) [OPTIONS] <name>
OPTIONS:
-p "<packages>" The list of packages to install in the container.
The default is blank.
-g "<groups>" The groups of packages to install in the container.
The default is "Core".
-y <yumconf> The path to the yum config to install packages from. The
default is /etc/yum.conf for Centos/RHEL and /etc/dnf/dnf.conf for Fedora
EOOPTS
exit 1
}
# option defaults
yum_config=/etc/yum.conf
if [ -f /etc/dnf/dnf.conf ] && command -v dnf &> /dev/null; then
yum_config=/etc/dnf/dnf.conf
alias yum=dnf
fi
install_groups="Core"
while getopts ":y:p:g:h" opt; do
case $opt in
y)
yum_config=$OPTARG
;;
h)
usage
;;
p)
install_packages="$OPTARG"
;;
g)
install_groups="$OPTARG"
;;
\?)
echo "Invalid option: -$OPTARG"
usage
;;
esac
done
shift $((OPTIND - 1))
name=$1
if [[ -z $name ]]; then
usage
fi
target=$(mktemp -d --tmpdir $(basename $0).XXXXXX)
set -x
mkdir -m 755 "$target"/dev
mknod -m 600 "$target"/dev/console c 5 1
mknod -m 600 "$target"/dev/initctl p
mknod -m 666 "$target"/dev/full c 1 7
mknod -m 666 "$target"/dev/null c 1 3
mknod -m 666 "$target"/dev/ptmx c 5 2
mknod -m 666 "$target"/dev/random c 1 8
mknod -m 666 "$target"/dev/tty c 5 0
mknod -m 666 "$target"/dev/tty0 c 4 0
mknod -m 666 "$target"/dev/urandom c 1 9
mknod -m 666 "$target"/dev/zero c 1 5
# amazon linux yum will fail without vars set
if [ -d /etc/yum/vars ]; then
mkdir -p -m 755 "$target"/etc/yum
cp -a /etc/yum/vars "$target"/etc/yum/
fi
if [[ -n "$install_groups" ]];
then
yum -c "$yum_config" --installroot="$target" --releasever=/ --setopt=tsflags=nodocs \
--setopt=group_package_types=mandatory -y groupinstall $install_groups
fi
if [[ -n "$install_packages" ]];
then
yum -c "$yum_config" --installroot="$target" --releasever=/ --setopt=tsflags=nodocs \
--setopt=group_package_types=mandatory -y install $install_packages
fi
yum -c "$yum_config" --installroot="$target" -y clean all
cat > "$target"/etc/sysconfig/network <<EOF
NETWORKING=yes
HOSTNAME=localhost.localdomain
EOF
# effectively: febootstrap-minimize --keep-zoneinfo --keep-rpmdb --keep-services "$target".
# locales
rm -rf "$target"/usr/{{lib,share}/locale,{lib,lib64}/gconv,bin/localedef,sbin/build-locale-archive}
# docs and man pages
rm -rf "$target"/usr/share/{man,doc,info,gnome/help}
# cracklib
rm -rf "$target"/usr/share/cracklib
# i18n
rm -rf "$target"/usr/share/i18n
# yum cache
rm -rf "$target"/var/cache/yum
mkdir -p --mode=0755 "$target"/var/cache/yum
# sln
rm -rf "$target"/sbin/sln
# ldconfig
rm -rf "$target"/etc/ld.so.cache "$target"/var/cache/ldconfig
mkdir -p --mode=0755 "$target"/var/cache/ldconfig
version=
for file in "$target"/etc/{redhat,system}-release
do
if [ -r "$file" ]; then
version="$(sed 's/^[^0-9\]*\([0-9.]\+\).*$/\1/' "$file")"
break
fi
done
if [ -z "$version" ]; then
echo >&2 "warning: cannot autodetect OS version, using '$name' as tag"
version=$name
fi
tar --numeric-owner -c -C "$target" . | docker import - $name:$version
docker run -i -t --rm $name:$version /bin/bash -c 'echo success'
rm -rf "$target"