VM disk cleanup script to minize its size

cleanup.sh

###
# Script which helps to minimize the final image size
###

# Set default value of the input variables
CI_STEP=${CI_STEP:-null}
EXPORT_TYPE=${EXPORT_TYPE:-null}

# Use sudo if not root
CMD="bash"
if [ $UID != 0 ]; then
    CMD="sudo -s"
fi

$CMD -- <<END
    if [ $CI_STEP == "soe" ]; then
        # Required for the next CI steps where we can not type the sudo password
        echo "==> Create sudoers file for the cfgmgmt user"
        echo "cfgmgmt  ALL=(ALL:ALL) NOPASSWD: ALL" > /etc/sudoers.d/cfgmgmt
    fi

    echo "==> Clean up yum cache of metadata and packages to save space"
    yum -y --enablerepo='*' clean all

    echo "==> Clear core files"
    rm -f /core*

    echo "==> Removing temporary files used to build box"
    rm -rf /tmp/*

    echo "==> Rebuild RPM DB"
    rpmdb --rebuilddb
    rm -f /var/lib/rpm/__db*

    echo "==> Remove mac address from eth0 configuration"
    sed -i -r '/^(HWADDR|UUID)/d' /etc/sysconfig/network-scripts/ifcfg-eth0

    echo "==> Remove net udev rules"
    rm -f /etc/udev/rules.d/70-persistent-net.rules

    echo "==> Clear out swap and disable until reboot"
    set +e
    swapuuid=$($SUDO /sbin/blkid -o value -l -s UUID -t TYPE=swap);
    case "$?" in
        2|0) ;;
        *) exit 1 ;;
    esac
    set -e

    if [ "x${swapuuid}" != "x" ]; then
        # Whiteout the swap partition to reduce box size
        # Swap is disabled till reboot
        swappart="`readlink -f /dev/disk/by-uuid/$swapuuid`"
        /sbin/swapoff "$swappart"
        dd if=/dev/zero of="$swappart" bs=1M || echo "dd exit code $? is suppressed"
        /sbin/mkswap -U "$swapuuid" "$swappart"
    fi

    echo "==> Zeroing out empty area to save space in the final image"
    dd if=/dev/zero of=/EMPTY bs=1M || echo "dd exit code $? is suppressed"
    rm -f /EMPTY

    echo "==> Syncing disks"
    sync
END