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 will make the template from a stage3 file. An OpenVZ OS template should be an archive (.tar.gz) of the root of a 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-i686-2008.0_beta2.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 VE config

Add the following to /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 a non-working df command.

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.

Replace /etc/fstab

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

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

Edit /etc/inittab

Edit /vz/private/777/etc/inittab and put a hash mark (#) at the beginning of the lines containing:

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

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

Edit /etc/shadow

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

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

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

Disable unneeded init scripts

The checkroot and consolefont init scripts should not be started inside VEs:

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

Edit /sbin/rc

Edit /vz/private/777/sbin/rc and put a hash mark (#) at the beginning of line 244 (your line number may be different):

# try mount -n ${mntcmd:--t sysfs sysfs /sys -o noexec,nosuid,nodev}

This prevents the VE from attempting to mount /sys.

To ensure that this change isn't automatically overwritten on update, add the following to /vz/private/777/etc/make.conf:

CONFIG_PROTECT = /sbin/rc

Set up udev

NOTE: udev-state does not exists anymore!! ../lib/udev/state and ../lib/udev/devices are empty directories now... maybe someone knows how to handle it the right way?

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

Edit /vz/private/777/etc/conf.d/rc and change the RC_DEVICES line to:

RC_DEVICES="static"

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 the VE:

vzctl stop 777

Making 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 the VE with the "bind" option. Do the following on the host after the VE is started:

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

If your /usr/portage/distfiles directory resides on a different partition than your /usr/portage directory, do the following:

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

Now, to install a package into a VE, you just need to enter the VE using 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, you should have these directories mounted only while installing software into a VE.

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

Create the template cache file

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

Test the new template cache file

Create a new VE from the template file:

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

If the VE was 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!