Fedora template update

This article describes the procedure of manual template update, using Fedora template as an example.

This is useful in the case you have some precreated template which is a bit old, and you want to create many containers based on it. To escape the updating of all those new containers right after their creation, it makes sense to update the template itself.

The idea is simple: you create a temporary container, start it, run the update cycle and then pack the results into a tarball. Some caution must be taken in order for this tarball to be clean though.

The below instructions are for updating Fedora 7 template for PPC architecture, using VEIDs 111 and 222 as temporary containers. Please substitute your own VEIDs and template names.

Creating/starting a temporary container

You should create a temporary container first.

# vzctl create 111 --ostemplate fedora-7-ppc-minimal 

Next you should assign a proper IP address to it. This IP does not have to be public -- see Using NAT for VE with private IPs.

# vzctl set 111 --ipadd 10.0.0.111 --save

Then add a nameserver to the containter. This is necessary so the container and yum can resolve hostnames:

# vzctl set 111 --nameserver <ip addr>

Finally, start your new container:

# vzctl start 111

Updating a container

First, enter a container:

# vzctl enter 111

Check that you can access Internet:

# ping -c 1 www.ru 
PING www.ru (194.87.0.50) 56(84) bytes of data.
64 bytes from www.ru (194.87.0.50): icmp_seq=1 ttl=56 time=1.92 ms

--- www.ru ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 1.920/1.920/1.920/0.000 ms

Next, run the update procedure:

# yum -y update

As this can take a few minutes or even hours, this is good time to go make some coffee.

Clean up

Сlean the yum repository inside a container to minimize:

# yum clean all

Еxit from a container and stop it:

# logout
exited from VE 111
# vzctl stop 111

Remove the IP from the container:

# vzctl set 111 --ipdel all --save

Packing a new template cache

Now, rename or remove the existing template cache:

# mv /vz/template/cache/fedora-7-ppc-minimal.tar.gz /vz/template/cache/fedora-7-ppc-minimal.tar.gz-old

Now create a new tarball:

# cd /vz/private/111
# tar czf /vz/template/cache/fedora-7-ppc-minimal.tar.gz .

Clean up:

# vzctl destroy 111

Testing

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

# ls -lh /vz/template/cache/fedora-7-ppc-minimal*
-rw-r--r-- 1 root root  99M 2007-11-13 18:11 /vz/template/cache/fedora-7-ppc-minimal.tar.gz
-rw-r--r-- 1 root root  91M 2007-08-31 02:46 /vz/template/cache/fedora-7-ppc-minimal.tar.gz-old

The sizes should not differ much.

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

# vzctl create 222 --ostemplate fedora-7-ppc-minimal
# vzctl set 222 --ipadd 10.0.0.222 --save
# vzctl start 222
# vzctl enter 222

Now execute a few basic commands to check container is fine. Examples are: ps ax, rpm -qa, etc.

Finally, clean up the testing container:

# vzctl stop 222
# vzctl destroy 222
# rm /etc/vz/conf/222.conf.destroyed