Irrvuan is a set of crude and simple bash scripts to build Devuan disk images suitable for plugging into a virtual machine provider like qemu or VirtualBox.
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Irrvuan is basically a glorified wrapper script for debootstrap and some standard system tools.
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It allows for easy configurable scripted installation of the Devuan OS to a loop-mounted file to produce bootable disk images. It should work with genuine Debian and derived distributions, too. That, however, has not been tested by the author yet.
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Irrvuan is not intended to be a replacement for the Devuan installer, though it could probably be tweaked and (ab)used to install a system to a physical disk drive. Or one could simply
ddthe resulting image to a physical drive. Moreover, it is not very flexible with respect to the used partitioning scheme. -
Irrvuan is not a replacement for the Devuan Simple Distro Kit, which is far more sophisticated and has a much broader range of possible applications.
I wanted to have available a simple tool to mass produce Devuan OS images for testing purposes. Plus, I needed to brush up my rusty shell programming skills. ;-)
Clone the repository and cd into the irrvuan directory. You
should perform all operations in this directory. So make sure to
have sufficient free space on the file system to hold the
generated image files!
A lot of operations performed by build-image.sh require
superuser permissions. A poor choice of configuration settings,
especially in main.cfg, can potentially cause severe damage to
the build system! The author of this script takes no liability
whatsoever for any damage caused by running it on your machine,
you do so at your own risk. You have been warned!
NOTE: The script uses sudo to gain root permissions where
needed. Thus you need to have sudo installed and configured
for your user, preferably with a decent password timeout. Or even
no password configured at all, if your personal security standards
would permit. (BTW: build-image.sh will not litter your working
directory with files owned by root, all superuser operations are
restricted to the target image file which is owned by your user
account.)
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The main script is called
build-image.sh. It draws on several modules:helperandstage_0tostage_3and expects at least one required argument, namely the name of a flavor to build, e.g.:./build-image.sh basic -
The
main.cfgfile contains the basic build environment settings. You should not modify it unless you really know what you're doing! An alternative main configuration file can be passed to the script by using the-coption, e.g.:./build-image.sh -c myconf basic -
The
builddirectory is where the generated disk images are created. In a similar fashion thelog,mntandtmpdirectories are used to place log-files, mount-points and temporary files, respectively. If you want to tidy up your Irrvuan tree you can just delete everything inside these directories, or even the directories itself - they get recreated the next time thebuild-image.shscript is executed. -
The
flavordirectory is where you will do most of the work. It contains a subdirectory for each system configuration variant, called a flavor. Flavors can build up on one another, so you can easily create more elaborate configurations by building up on simpler ones without having to duplicate the entire configuration. Likewise, changes you make to a flavor will automatically propagate to other flavors that build upon it.
Each flavor subdirectory may contain the following elements:
overlay
a directory containing files and folders that will be copied to the resulting disk image during stage 3 (see below).
xtrapkg
a directory containing additional
.debpackages to be installed during stage 3.
base
a file that should either be empty or consist of a single line that references another flavor the current one builds up on.
chrootinst
a script that is run via
chrootinside the target system.
config
file containing bash variable definitions for various aspects of the system image to be generated.
pkglist
list of additional packages to be installed or purged via
apt-get, or to be configured bydpgk-reconfigure.
boot
boot loader configuration files used during live image generation
In theory all of the components mentioned above are optional.
However, it is advisable to have all of them present at least in
the basic flavor definitions you intend to use. In higher level
flavors on the other hand it is common to omit components that
are not needed to add or change any settings. (However, the
base file will of course always be present in such cases, as
it provides the required link to the next lower level flavor.)
See the flavor/README.md file to learn more about the makeup
of flavors and the available settings.
When the build-image.sh script is run with the name of a flavor
as argument, it will first trace the chain of flavor dependencies
by evaluating the base files, merge the components of all linked
flavors in a temporary directory and then progress through the
build phases outlined below to finally produce a single virtual
disk image file containing a complete target system installation.
A trap handler will allow for graceful termination in case the script encounters an error condition or is interrupted by the user. This should take care of clearing out any dangling mounts or loop device associations.
Progressing along the flavor link chain from bottom to top, the following operations take place:
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The respective
overlay,xtrapkgandbootfolders of all linked flavors are amalgamated, i.e. they are copied on top of each other, to the effect that files in higher level flavors will potentially overwrite already existing ones originating from subordinate flavors. -
The respective
chrootinst,pkglistandconfigfiles of all flavors are concatenated, in order. The resulting files thus each contain all the information that was originally present in the individual files. -
The resulting
configfile is sourced to obtain a complete set of build variables. The build environment is then initialized accordingly.
The disk image file is created as prescribed by the build
configuration. A partition table is written and the image is then
associated with partition loop devices using losetup; the boot
and root file systems are initialized and mounted.
The base system is installed by running debootstrap as configured.
All of overlay, xtrapkg, pkglist and chrootinst is copied to
the loop device. A defined set of special variables in chrootinst
as well as in all files coming from the merged overlay directory
get substituted. The chrootinst script is executed inside a chroot
environment on the target system.
The chrootinst script is an essential component, as it is here
where vital tasks like e.g. password configuration, additional
package installation and final boot loader setup are performed.
You are encouraged to have a closer look at the included example
flavors, particularly the one named basic, to get a more detailed
notion of what this is about.
This step is optional: If enabled in the configuration, additional
ISO and / or USB images are produced that can be burned to a CD or
DVD or booted straight from a USB pen drive. The contents of the
merged boot flavor folders is included during image creation.
USB live images have added support for file backed persistence.
The supplemental raw2cooked.sh script can aid you in converting
the 'raw' disk images produced by build-image.sh into one of several
formats commonly accepted by various virtual machines, like e.g.
qcow or vdi. It should be pretty self-explanatory.
The qrun.sh script is a trivial convenience wrapper for qemu-system.
| Version | Comment |
|---|---|
| 0.0.1 | "pro bono" |
Irrvuan is distributed under the Modified ("3-clause") BSD License.
See the LICENSE file for more information.