cowbuilder

This is the tutorial for cowbuilder. See also qemubuilder.

Usage

Initialization

Create the base image:

sudo cowbuilder --create

And a new and shiny build image is created in /var/cache/pbuilder/base.cow/

Every day usage

Update the base image

sudo cowbuilder --update

Build a package:

sudo cowbuilder --build somepackage.dsc

Tips

Bash and SVN tips

Setup your .bashrc according to: http://upsilon.cc/~zack/blog/posts/2007/09/svn-cowbuilder/

Building your package for many distributions at once

cowbuilder is really handy to build your pet project for many distributions at once. If you have got an amd64 system, you can easily build a package for i386 and amd64 architectures and for say stable, sid and lucid.

sudo mkdir  /var/cache/pbuilder/squeeze-i386/

sudo cowbuilder \
--create \
--basepath /var/cache/pbuilder/squeeze-i386/base.cow\
 --distribution squeeze\
 --debootstrapopts --arch --debootstrapopts i386

Creating an ubuntu base path is trickier because one must :

$ DIST=gutsy sudo cowbuilder --create --distribution gutsy --components "main universe" --basepath /var/cache/pbuilder/gutsy-amd64.cow --mirror http://apt:9999/ubuntu --debootstrapopts --exclude=udev,pcmciautils,initramfs-tools

dget http://ftp.de.debian.org/debian/pool/main/n/nano/nano_2.2.6-1.dsc
cd nano-2.2.6
# For a Debian Squeeze on i386 target
sudo DIST=squeeze ARCH=i386 pdebuild
# Ubuntu a Hardy on amd64 target
sudo DIST=hardy ARCH=amd64 pdebuild

The result will be available in: /var/cache/pbuilder/squeeze-i386/result

Optionnal

set -e

RESULTDIR=$1
[ -d $RESULTDIR ] || mkdir $RESULTDIR

DISTLIST=$(ls -d /var/cache/pbuilder/*.cow)

for chrootdir in $DISTLIST
do
    sudo cowbuilder --update --basepath $chrootdir
    DIST=$(basename $chrootdir | cut -d'-' -f1)
    [ -d $RESULTDIR/$DIST ] || mkdir $RESULTDIR/$DIST
    DIST=$DIST pdebuild --pbuilder cowbuilder\
                        --buildresult $RESULTDIR/$DIST\
                        -- --basepath $chrootdir
done

( you shoud then add --mirror http://apt:9999/debian 

Troubleshooting

Slow copying and removing of the COW directory

What cowbuilder does is:

cp -al /var/cache/pbuilder/base.cow /tmp/new
rm -rf /tmp/new

Of course cowbuilder uses a different location than /tmp/new. You need to optimize those 2 commands on your computer. They should take around 0.2s each. If not, try to use the ext3 filesystem, for more details, see our benchmarks.