rbootstrap is a tool for setting up RPM based Linux distributions in chroot jails. The goal of the project is to have a tool like debootstrap for Debian and Ubuntu for RPM based distributions like CentOS, RedHat, OpenSuSE, SLES and so on.

I started development of rbootstrap to create a lighweight tool which offers a fast forward way to create installations of the mentioned Linux distributions without the need to set-up a full blown virtualisation environment.

In my case I needed it to create my own small build service for compiling a software for different Linux distributions with different architectures. Based on experiences from other projects I knew that full or para virtualized environments were too much overhead for my needs. After setting up the build service for Debian and Ubuntu I started searching for working lightweight solutions for OpenSUSE, CentOS etc., but I was unable to find up-to-date and usable ones. So I decided to start this small project.

Hope it is usable for someone out there. Let me know!

Download the git or a release tarball. In case of the release tarball you first need to unpack it (tar xvzf rbootstrap-<version>.tar.gz) and then change into the just created directory (cd rbootstrap-<version>).

To install the downloaded version of rbootstrap use this command:

python setup.py install

After this you should be able to execute rbootstrap --help.

The common use case is to call rbootstrap once for setting up a chroot jail below a path of your choice.

For example, to create a jail for CentOS 6.0 in the directory /var/lib/centos_6.0_jail on my Ubuntu system, I used the following command:

> sudo rbootstrap centos_6.0 /var/lib/centos_6.0_jail
+- Initializing jail -----------------------------------------------------------
+- Creating device nodes -------------------------------------------------------
+- Mounting needed filesystems -------------------------------------------------
+- Reading repository meta information -----------------------------------------
+- Resolving package dependencies ----------------------------------------------
+- Loading repositories GPG key ------------------------------------------------
+- Loading packages ------------------------------------------------------------
+- Unpacking packages to create initial system ---------------------------------
+- Installing base packages ----------------------------------------------------
(...)
+- Cleaning up jail mounts and processes ---------------------------------------

The setup copies /etc/hostname and /etc/resolv.conf from the host to the jail to make network communication possible. While setup the /proc and /sys filesystems of the host are mounted to the jail.

After starting the command, rbootstrap does its work and, when no error happend, leaves the prepared jail in /var/lib/centos_6.0_jail. You can now use it for whatever you like. The most simple task would now be to change into the jail and, for example, install additional needed packages.

> sudo chroot /var/lib/centos_6.0_jail
> yum install vim
(...)

To have a more complete working environment, you might need to perform some other actions before changing into the jail, for example mount the /proc and /sys filesystems. Maybe you also like to set a custom prompt (PS1) which might prevent you from accidental command execution within or outer the jail.

Please be aware: When you have mounted filesystems to the jail and try to remove it e.g. with rm -rf, you might delete contents of these filesystems by accident. So always ensure that you have unmounted all filesystems from a jail before trying to delete the jail.

Take a look at the output of rbootstrap --help for details about how to call rbootstrap and which options are available.

rbootstrap is written in Python. This is the major requirement for make this tool work. It has been developed on Ubuntu 14.04 with Python 2.7, but it aims to work with Python down till 2.4. If you experience any problems with older Python versions, please report it!

This tools makes use of several system utilities, which need to be available to make it work. These are at the moment:

• chroot
• mount / umount

I am trying to keep the dependencies as small as possible. Please let me know when you got easy solutions to remove one of the dependencies mentioned above.

At the moment there is support to install the following distributions in a chroot:

• OpenSUSE 13.1
• CentOS 6.0 - 7.0
• Fedora 18 - 20
• SLES (SuSE Linux Enterprise Server) 11.0 - 12.0

This list might not be always up-to-date, please take a look at the files in the distros directory to get the real list of supported ones.

Maybe you can add one or two missing distributions? Would be appreciated!

It is easily possible to use local installation media like a ISO image or an inserted DVD containing the installation files for the distro.

Assuming you like to create a jail for CentOS 6.5 and have the installation DVD1 ISO file located in /tmp/CentOS-6.5-x86_64-bin-DVD1.iso. Now the easiest way to use this local file instead of a public HTTP mirror is to mount the ISO and point rbootstrap to this path.

> sudo -s
# mkdir /media/tmp
# mount -o loop /tmp/CentOS-6.5-x86_64-bin-DVD1.iso /media/tmp

Now you should see the contents of the ISO image below /media/tmp, for example a directory called repodata. Then call `rbootstrap as follows, watch the progress and enjoy.

# rbootstrap --mirror /media/tmp centos_6.5 /var/lib/centos_6.5.jail
+- Initializing jail -----------------------------------------------------------
+- Creating device nodes -------------------------------------------------------
+- Erasing existing jail -------------------------------------------------------
+- Initializing jail -----------------------------------------------------------
+- Creating device nodes -------------------------------------------------------
+- Reading repository meta information -----------------------------------------
+- Resolving package dependencies ----------------------------------------------
+- Loading repositories GPG key ------------------------------------------------
+- Loading packages ------------------------------------------------------------
+- Unpacking packages to create initial system ---------------------------------
+- Mounting needed filesystems -------------------------------------------------
+- Installing base packages ----------------------------------------------------
(...)
+- Cleaning up jail mounts and processes ---------------------------------------
+- Cleaning up downloaded files ------------------------------------------------
+ ==============================================================================
| JAIL CREATED!
+ ------------------------------------------------------------------------------
| You can now change to the jail using this command:
|
|   rbchroot /var/lib/centos_6.5.jail
|
| If you just like to execute single commands without opening a shell in the
| jail, use the rbchroot command like this:
|
|   rbchroot /var/lib/centos_6.5.jail echo "I'm jailed. Wheee!"
|
+ ==============================================================================

And don't forget to cleanup after finishing this task:

# umount /media/tmp
# rmdir /media/tmp

You can easily use a real DVD inserted into your computer. You only need to mount it (or find the mount point your OS auto mounted the disk to) and point rbootstrap to it.

I decided to use GitHub for managing project related communication, you can find the project at (https://github.com/LaMi-/rbootstrap).

Copyright (C) 2014 Lars Michelsen lm@larsmichelsen.com

All outcome of the project is licensed under the terms of the GNU GPL v2. Take a look at the LICENSE file for details.