Easy creating and destroying of lxc vservers

One big advantage of using amazon's EC2 servce is its deceptively easy way to create new servers - it is just API call or mouseclick away. The actual physical machine allocation, OS image copying, hostname, IP, dns, firewall and routing setup are done transparently in the background. You are only required to setup the payment ;) .

Big enterprise virtualization technology providers already have a mechanism to create virtual machines with given parameters on demand. Such a system would likely be overkill for a handful of physical servers. I also doubt they support the highly effective pseudo-virtualization LXC technology.

Thus I created a python "lmachine" script for our LXC servers, that copies an OS image into a selected "slot" with already pre-allocated IP number and server name. The script also modifies a couple of system files from the OS image accordingly.

The script can be downloaded here.

Preparing an LXC image

LXC images are easily created using the debootstrap utility. To make them ready for the lmachine script, you need to set the actual IP number with the IPNUMBER string and the actual server name with the VSERVERNAME string. Here is the list of files that needs to be modified:

• fstab
• lxc.conf
• root/etc/network/interfaces
• root/etc/hosts
• root/etc/hostname
• root/etc/mailname

Make sure you pre-allocate IP numbers and ltestXX DNS domain names in advance. Update the lmachine script with the list of pre-allocated IP numbers.