Updating Debian template

This article describes how you can update an existing precreated Debian or Ubuntu template. The procedure is pretty easy.

Creating/configuring a temporary container

First, you need to create a container based on the template you want to update. Here is an example:

[HN]# vzctl create 555 --ostemplate debian-4.0-i386-minimal

Next, you want to specify an IP address and a nameserver:

[HN]# vzctl set 555 --ipadd x.x.x.x --nameserver y.y.y.y --save

You can get the value of nameserver from your /etc/resolv.conf. Your container should have an Internet access, so you either supply a public IP, or see using NAT for container with private IPs for information about how to use private IP and NAT.

Then start your container:

[HN]# vzctl start 555

Finally, check that Internet is working from inside your container:

[HN]# vzctl exec 555 ping -n -c 1 www.ru

Update

Enter the container:

[HN]# vzctl enter 555

Update metadata and install updates:

[container]# apt-get update && apt-get upgrade

Cleanup:

[container]# apt-get clean
[container]# > /etc/resolv.conf

Clean unused log files, .bash_history etc, then exit from a container:

[container] # exit

Stop a container, remove its IP:

[HN]# vzctl stop 555
[HN]# vzctl set 555 --ipdel all --save

Packing a new template cache

Now, rename the existing template cache:

[HN]# mv /vz/template/cache/debian-4.0-i386-minimal.tar.gz{,-old}

Now create a new tarball:

[HN]# cd /vz/private/555
[HN]# tar --numeric-owner -czf /vz/template/cache/debian-4.0-i386-minimal.tar.gz .

Clean up:

[HN]# vzctl destroy 555
[HN]# rm -f /etc/vz/conf/555.conf.destroyed

Test new template cache

First, compare the sizes of the old and the new template caches:

[HN]# ls -lh /vz/template/cache/debian-4.0-i386-minimal*
-rw-r--r-- 1 root root  55M 2007-11-13 18:11 /vz/template/cache/debian-4.0-i386-minimal.tar.gz
-rw-r--r-- 1 root root  53M 2007-08-31 02:46 /vz/template/cache/debian-4.0-i386-minimal.tar.gz-old

The sizes should not differ much.

Try to create and start container made from your new template:

[HN]# vzctl create 222 --ostemplate debian-4.0-i386-minimal
[HN]# vzctl set 222 --ipadd 10.0.0.222 --save
[HN]# vzctl start 222
[HN]# vzctl enter 222

Now execute a few basic commands to check container is fine. Examples are: ps axf, dpkg -l, etc.

Finally, clean up the testing container:

[HN]# vzctl stop 222
[HN]# vzctl destroy 222
[HN]# rm -f /etc/vz/conf/222.conf.destroyed