Gentoo template creation

This page is about making a template cache for OpenVZ VE from Gentoo Linux. The method is basically the same as described in Slackware template creation article.

Download stage3

We shall make the template from stage3 file. OpenVZ OS template should be an archive of root of the working system, but without the kernel and some files. You can download stage3 from the nearest mirror here: http://www.gentoo.org/main/en/mirrors.xml.

Create directory for the new VE and unarchive stage3

mkdir /vz/private/777
tar -xjf /root/stage3-i686-2006.0.tar.bz2 -C /vz/private/777

Create VE config

Now you need to create the configuration file for the VE, 777.conf:

vzctl set 777 --applyconfig vps.basic --save

Edit config

Add to the /etc/vz/conf/777.conf:

DISTRIBUTION="gentoo"
OSTEMPLATE="gentoo"

Make /etc/mtab a symlink to /proc/mounts

The VE root filesystem is mounted by the host system, not the guest -- and therefore root fs will not appear in /etc/mtab. It will lead to df command non-working.

rm -f /vz/private/777/etc/mtab
ln -s /proc/mounts /vz/private/777/etc/mtab

After replacing /etc/mtab with a symlink to /proc/mounts, you will always have up-to-date information of what is mounted in /etc/mtab.

Edit /etc/fstab

echo "proc /proc proc defaults 0 0" > /vz/private/777/etc/fstab

We need only /proc to be mounted at the boot time.

Edit /etc/inittab

Edit /vz/private/777/etc/inittab, putting a hashmark (#) before the lines containing:

c?:1235:respawn:/sbin/agetty 38400 tty? linux

This prevents from starting getty and login on ttys that does not exist in VEs.

Edit /etc/shadow

Edit /vz/private/777/etc/shadow, change root's password in the first line to an exclamation mark (!):

root:!:10071:0:::::

This will disable the root login until the password changed with vzctl set VEID --userpasswd root:password.

Edit /etc/init.d/checkroot

The checkroot script should not be enabled on boot

rm /vz/private/777/etc/runlevels/boot/checkroot

Edit /sbin/rc

Comment line number 141 in /vz/private/777/sbin/rc:

try mount -n ${mntcmd:--t sysfs sysfs /sys}

This prevents from attepting to mount /sys.

To ensure these changes aren't automatically overwritten on update, add the following to /vz/private/777/etc/make.conf:

CONFIG_PROTECT = /sbin/rc

Set up udev

Delete /lib/udev-state/devices.tar.bz2 and create some device nodes needed to enter a VE:

cd /vz/private/777/lib
rm udev-state/devices.tar.bz2
mknod udev/devices/ttyp0 c 3 0
mknod udev/devices/ptyp0 c 2 0
mknod udev/devices/ptmx c 5 2

Set RC_DEVICES="static" in /vz/private/777/etc/conf.d/rc

You have to leave the directory you are in for the next step to be ok, otherwise you will get this error message :
vzquota : (error) Quota on syscall for 777: Device or resource busy
vzquota on failed [3]

cd /

Test

vzctl start 777
vzctl enter 777

You can check running services.

rc-status -a

All services in boot and default runlevels must be started. If everything all right, stop it

vzctl stop 777

Make distfiles and portage tree of the host system available in a VE

Warning: This step is optional and will result in shared files between VEs! These steps can save space on disk but trade isolation and security... consider your options carefully!

To install software into a VE with portage you should mount /usr/portage into VE with "bind" option. Do this after VE starts:

mkdir /vz/root/777/usr/portage
mount -o bind /usr/portage /vz/root/777/usr/portage

If your /usr/portage/distfiles placed on the other partition do:

mount -n -o bind /usr/portage/distfiles /vz/root/777/usr/portage/distfiles

Now, to install package into a VE you just need enter there by vzctl enter and run

emerge package_name

while you have all the needed files in the /usr/portage/distfiles of host system.

For security reasons hold this directories mounted only while you are installing software into a VE.

Note: you have to umount /vz/root/777/usr/portage/distfiles before trying to stop your VE.

Create the cache file

cd /vz/private/777/
tar czf /vz/template/cache/gentoo.tar.gz *

Test the new cache file

vzctl create 800 --ostemplate gentoo --ipadd 192.168.0.10 --hostname testvps

If created successfully, try to start it:

vzctl start 800

If it started, and you can ssh in, congratulations, you've got a working Gentoo template!