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== Introduction ==

This document describes the steps to setup a chroot with schroot on an lvm module, so that you can build packages on an lvm-snapshot. It tries to provide an alternative to PbuilderHowto

The following assume you want to install ''dapper''. If you need a ''hoary'' or ''breezy'' chroot, then exchange ''dapper'' with the appropriate distribtion.

== Installing required packages on dapper ==

You need a very recent version of schroot. I used version 0.2.8-1ubuntu1 for this Howto.

Just install the following packages on a dapper system:

apt-get install schroot sbuild

== creating lvm volumes ==

in order to create an lvm volume, you first need to prepare one or more partitions (or other block devices) for use as physical volume:

pvcreate /dev/md1

Then you add these physical volumes to a new volume group:

vgcreate data00 /dev/md1

Once this is done, you can now create a new logical volume. The following commands creates a new logical volume 'dapper_chroot' with the size of 5GB in a volumegroup called 'data00':

lvcreate -n dapper_chroot -L 5g data00

you can now create a filesystem on it and mount it:

mkfs -t ext3 /dev/data00/dapper_chroot
mount /dev/data00/dapper_chroot /mnt

== bootstrapping a base system ==

Now you can bootstrap your favorite distribution on that:

debootstrap dapper /mnt

Perhaps you want your /etc/sudoers and sources.list copied into that chroot, so that you can easily become root inside:

sudo cp /etc/sudoers /mnt/etc
sudo cp /etc/apt/sources.list /mnt/etc/apt

Unmount this temporary mountpoint now, schroot will mount it itself:

umount /mnt

== configuring schroot ==

edit '/etc/schroot/schroot.conf' to contain this stanza:

description=Ubuntu Dapper
mount-options=-o noatime
lvm-snapshot-options=--size 1G

== Entering the chroot ==

If you want to change the 'original' chroot, you can chroot into that with the following command:

schroot -c dapper-source

All changes you make there are persistent. So if you want to upgrade that chroot, use the following commands:

schroot -c dapper-source -u root -- apt-get update
schroot -c dapper-source -u root -- apt-get -y dist-upgrade
schroot -c dapper-source -u root -- apt-get get install build-essential ubuntu-minimal fakeroot devscripts

To enter the chroot on an lvm snapshot, use this command:

schroot -c dapper

Thanks to the session scripts, some directories, like /home, /proc, /sys and /tmp are mounted for you. You can modify/add session scripts in /etc/schroot/setup.d/*

== sbuild ==

For proper support for schroot, make sure you are in the system group 'sbuild'.

Create a file called '~/.sbuildrc' with the following contents:


# Mail address where logs are sent to (mandatory, no default!)
$mailto = "root";

# Name to use as override in .changes files for the Maintainer: field
# (mandatory, no default!).
$maintainer_name='Reinhard Tartler <>';

# Chroot behaviour; possible values are "split" (apt and dpkg are run
# from the host system) and "schroot" (all package operations are done in
# the chroot with schroot, but the chroot must allow networking)
$chroot_mode = "schroot";

# don't remove this, Perl needs it:


== building packages ==

You can build now packages with the following command on lvm snapshots:

sbuild -d dapper package_1.2.3-4.dsc

If anything goes wrong, use parameters '-v -D' to debug.

Good Luck!


SbuildLVMHowto (last edited 2008-08-06 16:38:56 by localhost)