Linux-Vserver
- or how to run multiple distributions on one and the same machine|
Author: Martin List-Petersen - martin at list-petersen dot dk The newest version of this document can allways be found at http://www.marlow.dk/vserver To see all pages of this document without menu etc. (for printing, opens new window), click here. Version: 0.01 Created: January 28th, 2005 Last updated: January 28th, 2005 |
Disclaimer: This document is provided AS IS, of course. Feel free to use the info provided here, but don't blame me, if it doesn't work. Feedback however is allways appreciated. I can't be made responsible for data loss or other damages in any way. Be aware, that this document is based on Debian and and the packages provided have only been tested an a Debian host. They should run on most distributions however.
Introduction
I've been using Vserver since around mid 2002, initially for test purposes and for hosting since the end of 2002 and must say, that it is a very easy way to deploy virtual servers. Thanks to Jacques Gelinas, the initial creator, and Herbert Pötzl, who has been pushing the project since around autumn 2003, for providing this invaluable piece of softwareThe reason for this document are Guest Images. Guest images are minimal builds of the distributions, that are run inside a Vserver.
Guest Images have allways been a problem, because it takes time to prepare them, if it's a guest image, that is based on another distribution, than the one you are running on the host machine. During time i've build my own deploying system for guest images and in January 2005 (with the creation of this document) made them available to anybody, who wants a peek at them or build further on. They are provided here as a ressource to the Linux-Vserver Project.
What is Linux-Vserver ?
Linux-Vserver is the reinvention (not porting) of BSD jails to Linux, but it goes further beyond. Linux-Vserver will provide you with a filesystem-chroot and a security context that locks the vserver in it's own environment. There are 3 things that cannot be changed in a vserver (unless you have root access to the host, which the vserver is deployed on): the ip address, the hostname and the kernel. All vservers on one machine share matter of fact the same Linux kernel. That way the overhead is absolutely minimal.Guest Images
All the images that I provide are build from publicly available downloads (FTP and ISO), so they can be freely distributed and modified. The images are very bare, usually just the absolute minimum to get up and running, and once deployed often only have syslogd and sshd running. All images are run on a Debian Host with kernel 2.4, i don't use 2.6 in production at this point of time. On top of that leaves to mention, that I don't care about unification of vservers, because i use vserver for hosting and harddisk space is inexpensive nowadays.None of the images allow root to log in via ssh, a security measure, that should be the default on any system. There is a user "admin" in place, that can be used for the initial connect, instead.
For deploying the images, basically all you need is the deploy-vserver.sh script. This script is self explaining and only a few default values have to be changed by editing the script, once downloaded. The script is provided under the GPLv2 exclusively (and not any older or newer release of the GPL !!). If an image not is available locally, the script will try to download it and it's corresponding diff file automatically.
The guest images consist of a tar-ball with the image, a diff file (not all of them) with the changes to rc files etc. and modifications done to the vserver image on the fly during deployment, handled by the script. Feel free to modify the script and images as you see fit.
If you want to peek at the images and diffs yourself, check them out. They are at: http://debian.marlow.dk/vserver/guest/.
