Now that CentOS 6.0 is long dead, and removed from the docker hub, how would you create your own image? It's easier than you think. Here's how!

Recently, I needed to build some software on a CentOS 6.0 docker image, and couldn't find one anywhere to use. I needed to create what docker calls a base image, which is essentially a tarfile of a root directory of a Linux image. Here's how I recreated the image. I borrowed heavily from this blog post but changed it for CentOS 6.0 specifically, which has deprecated yum repos.

First, grab the CentOS 6.0 ISO from the vault, and spin up a VM with it.

Once you have your VM and are logged into it, create a folder to be our rpm buildroot for our image:

export centos_root='/centos_image/rootfs'
mkdir -p $centos_root

Then, make sure to remove the deprecated CentOS 6.0 repo, and change it to the vault repos

mv -v /etc/yum.repos.d/CentOS-Base.repo{,-backup}
touch /etc/yum.repos.d/CentOS-Base.repo

Make CentOS-Base.repo into the following:

[C6.0-base] 
name=CentOS-6.0 - Base 
baseurl=http://vault.centos.org/6.0/os/$basearch/ 
gpgcheck=1 
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6 
enabled=1 

[C6.0-updates] 
name=CentOS-6.0 - Updates 
baseurl=http://vault.centos.org/6.0/updates/$basearch/ 
gpgcheck=1 
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6 
enabled=1 

[C6.0-extras] 
name=CentOS-6.0 - Extras 
baseurl=http://vault.centos.org/6.0/extras/$basearch/ 
gpgcheck=1 
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6 
enabled=1
CentOS-Base.repo

Then, download all the RPMs we need:

yum clean all
yum makecache
# install download plugin for yum
yum install yum-plugin-downloadonly
# 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 --nodeps centos-release*.rpm
rpm --root $centos_root --import $centos_root/etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
# install yum without docs and install only the english language files during the process
yum -y --installroot=$centos_root 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
# mount the device tree, as its required by some programms
mount -o bind /dev $centos_root/dev
chroot $centos_root /bin/bash <<EOF
yum install -y procps-ng iputils
yum clean all
EOF
rm -f $centos_root/etc/resolv.conf
umount $centos_root/dev

You're done! Now you can tar up the chroot, and it's importable into docker!

tar -cvzf centos-6.0-base.tar.gz -C $centos_root -c .
cat centos-6.0-base.tar.gz | docker import - taniumcentos:6.0