Forking means publishing your own modified version and is a common practice in Free Software. Forking a package repository is less common but useful nevertheless. Here is how it can be done for i386 using packaging-farm and the XiVO Debian GNU/Linux repository for lenny. The stable (Gallifrey) repository is preferred although it could be done with the more recent (Skaro) repository.
Extracting XiVO Gallifrey for Debian lenny
After creating a virtual machine based on the recently published Debian
GNU/Linux squeeze, packaging-farm is installed from the repository. Another
source is added to extract the XiVO packages in source form. Here we focus
on main but the same principle can be done for others.
deb http://dak.proformatique.com/debian/ lenny-xivo-gallifrey main deb-src http://dak.proformatique.com/debian/ lenny-xivo-gallifrey main
packaging-farm expects to find package sources in /var/cache/packaging-farm/sources
within a directory that is named after the package. This hierarchy was build with
the following:
awk '/^Package/{print $2}' /var/lib/apt/lists/dak.proformatique.com_debian_dists_lenny-xivo-gallifrey_main_source_Sources |
while read package
do
( rm -fr $package ; mkdir $package ; cd $package ; apt-get source $package )
done
In addition, a list of all known packages must be added to /etc/packaging-farm/packaging-farm.conf and a variable containing the directory where the chroot must be stored. The chroot is preserved if the build fail, for debuging purpose. To keep the structure consistent, a directory named after the package is created in /usr/src (/usr/src/asterisk, /usr/src/dahdi-linux etc.). Each directory must contain a Makefile that may contain exceptions or additional build instructions for the farm. Since there is no need for such tweaking at the moment, the Makefiles are generated:
for package in asterisk asterisk-addons asterisk-app-conference asterisk-chan-capi asterisk-chan-sccp asterisk-sounds-gsm-de-de asterisk-sounds-wav-en-us asterisk-sounds-wav-es-es asterisk-sounds-wav-fr-ca bntools dahdi-linux dahdi-tools libasterisk-perl libpri misdn-kernel misdn-user pf-asterisk-ami-aoriginate pf-asterisk-app-fax pf-asterisk-app-nv-faxdetect pf-asterisk-module-xivo pf-asterisk-prompt-fr pf-asterisk-prompt-fr-xivo pf-asterisk-prompts-xivo pf-asterisk-res-sqlite2 pf-asterisk-res-watchdog pf-asternic-stats pf-sources.list-ldlc pf-xivo pf-xivo-agid pf-xivo-backup pf-xivo-base-config pf-xivo-cti-server pf-xivo-cti-webclient pf-xivo-extra pf-xivo-fetchfw pf-xivo-lib-python pf-xivo-provisioning pf-xivo-queues-logger pf-xivo-sysconfd pf-xivo-utils pf-xivo-web-interface sangoma-wanpipe spandsp ; do
cat > /usr/src/$package/Makefile <<EOF
PACKAGE=$package
DISTRIBUTIONS=lenny
ARCHITECTURES=i386
LIBDIR ?= /usr/lib/packaging-farm
include \${LIBDIR}/Makefile
EOF
done
Source package dependencies
The packaging-farm does not know anything about source package dependencies. For instance a number of XiVO packages depend on asterisk, therefore they need to be rebuilt if a new asterisk package is published. In preparation for a patch submission to add support for source package dependencies, a set of shell commands have been performed to generate a set of dependencies written as Makefile entries:
# these lines are approximations that won't work out of the box
# list all packages for each source package
cat */*/debian/control | perl -ne 'print "$1|" if(s/^Package:\s*(.*)\s*//)'
# map package to corresponding source package
cat /tmp/list_of_source_packages | while read package ; do cat $package/*/debian/control | perl -ne 's/[.-]/_/g; print "$1='$package'\n" if(s/^Package:\s*(.*)\s*//)' ; done
# create the makefile entries
for package in asterisk asterisk-addons asterisk-app-conference asterisk-chan-capi asterisk-chan-sccp asterisk-sounds-gsm-de-de asterisk-sounds-wav-en-us asterisk-sounds-wav-es-es asterisk-sounds-wav-fr-ca bntools dahdi-linux dahdi-tools libasterisk-perl libpri misdn-kernel misdn-user pf-asterisk-ami-aoriginate pf-asterisk-app-fax pf-asterisk-app-nv-faxdetect pf-asterisk-module-xivo pf-asterisk-prompt-fr pf-asterisk-prompt-fr-xivo pf-asterisk-prompts-xivo pf-asterisk-res-sqlite2 pf-asterisk-res-watchdog pf-asternic-stats pf-sources.list-ldlc pf-xivo pf-xivo-agid pf-xivo-backup pf-xivo-base-config pf-xivo-cti-server pf-xivo-cti-webclient pf-xivo-extra pf-xivo-fetchfw pf-xivo-lib-python pf-xivo-provisioning pf-xivo-queues-logger pf-xivo-sysconfd pf-xivo-utils pf-xivo-web-interface sangoma-wanpipe spandsp ; do echo -n "$package :: " ; perl -ne 'if(/^Build-Depends/) { while(/(asterisk-mysql|asterisk-mp3|asterisk-ooh323c|asterisk-app-conference|asterisk-app-conference-dbg|asterisk|asterisk-common|asterisk-dev|asterisk-sounds-main|asterisk-web-vmail|asterisk-config|asterisk-classic|asterisk-classic-dbg|asterisk-chan-capi|asterisk-chan-capi-dbg|asterisk-chan-sccp|asterisk-chan-sccp-dbg|asterisk-sounds-gsm-de-de|asterisk-sounds-wav-en-us|asterisk-sounds-wav-es-es|asterisk-sounds-wav-fr-ca|bntools|pf-asterisk-res-bnfos|dahdi-linux-source|dahdi-linux-modules-common|dahdi-linux-dev|dahdi-tools|libtonezone1|libtonezone-dev|libasterisk-perl|libpri-dev|libpri1.4|misdn-kernel-source|misdn|misdn-headers|misdn-utils|misdn-dbg|libmisdn0|libmisdn-dev|libisdnnet0|libisdnnet-dev|pf-asterisk-ami-aoriginate|pf-asterisk-app-fax|pf-asterisk-app-fax-dbg|pf-asterisk-app-nv-faxdetect|pf-asterisk-module-xivo|pf-asterisk-prompt-fr|pf-asterisk-prompt-fr-xivo|pf-asterisk-prompt-fr-fr-xivo|pf-asterisk-prompt-fr-ca-xivo|pf-asterisk-res-sqlite2|pf-asterisk-res-sqlite2-dbg|pf-asterisk-res-watchdog|pf-asternic-stats|pf-sources.list-ldlc-xivo-1.1-gallifrey|pf-xivo-agid|pf-xivo-backup|pf-xivo-base-config|pf-xivo-cti-server|pf-xivo-cti-webclient|pf-xivo-extra|pf-xivo-fetchfw|pf-xivo-lib-python|pf-xivo|pf-xivo-debug-tools|pf-xivo-provisioning|pf-xivo-queues-logger|pf-xivo-sysconfd|pf-xivo-utils|pf-xivo-web-interface|pf-xivo-web-interface-config|sangoma-wanpipe-tools|sangoma-dbg|sangoma-wanpipe-source|libspandsp3|libspandsp-dev|libspandsp3-dbg|libspandsp-doc)/g) { print "$1\n"; } }' < /var/cache/packaging-farm/sources/$package/*/debian/control | sort -u | while read source ; do echo -n ' ' ; eval echo -n \$$(echo $source | sed -e 's/[.-]/_/g') ; done ; echo ; done
created:
# level 4 pf-asterisk-ami-aoriginate :: asterisk pf-asterisk-app-fax :: asterisk spandsp pf-asterisk-app-nv-faxdetect :: asterisk pf-asterisk-module-xivo :: asterisk pf-asterisk-res-sqlite2 :: asterisk pf-asterisk-res-watchdog :: asterisk asterisk-addons :: asterisk asterisk-app-conference :: asterisk asterisk-chan-capi :: asterisk asterisk-chan-sccp :: asterisk bntools :: asterisk # level 3 asterisk :: dahdi-linux misdn-user libpri dahdi-tools misdn-kernel # level 2 dahdi-tools :: dahdi-linux sangoma-wanpipe :: dahdi-linux misdn-user :: misdn-kernel # level 1 asterisk-sounds-gsm-de-de asterisk-sounds-wav-en-us asterisk-sounds-wav-es-es asterisk-sounds-wav-fr-ca dahdi-linux libasterisk-perl libpri misdn-kernel pf-asterisk-prompt-fr pf-asterisk-prompt-fr-xivo pf-asterisk-prompts-xivo pf-asternic-stats pf-sources.list-ldlc pf-xivo pf-xivo-agid pf-xivo-backup pf-xivo-base-config pf-xivo-cti-server pf-xivo-cti-webclient pf-xivo-extra pf-xivo-fetchfw pf-xivo-lib-python pf-xivo-provisioning pf-xivo-queues-logger pf-xivo-sysconfd pf-xivo-utils pf-xivo-web-interface spandsp ::
The dependencies were used to figure out the manual order in which the packages must be built. After checking that all packages without dependencies could be successfully built (misdn-kernel, dahdi-linux and more), the idea was to encode the dependencies in the Makefile for each package.
for i in asterisk-sounds-gsm-de-de asterisk-sounds-wav-en-us asterisk-sounds-wav-es-es asterisk-sounds-wav-fr-ca dahdi-linux libasterisk-perl libpri misdn-kernel pf-asterisk-prompt-fr pf-asterisk-prompt-fr-xivo pf-asterisk-prompts-xivo pf-asternic-stats pf-sources.list-ldlc pf-xivo pf-xivo-agid pf-xivo-backup pf-xivo-base-config pf-xivo-cti-server pf-xivo-cti-webclient pf-xivo-extra pf-xivo-fetchfw pf-xivo-lib-python pf-xivo-provisioning pf-xivo-queues-logger pf-xivo-sysconfd pf-xivo-utils pf-xivo-web-interface spandsp ; do ( echo --------------------------- ; echo $i ; cd $i ; make all ) ; done
In packaging-farm, when a package is built, a new debian repository is created just for this package and only contains its package. In the case of misdn-user the repository of misdn-kernel (see above : it depends on it) would need to be added to the description of the misdn-user package. Although this may be fine for a few packages, four level of dependencies makes it tedious and error prone. It would be unwise to try it manually.
Aggregation of the results
XiVO is made of dozens of packages and it would be most inconvenient to add so many lines to a source list. Instead, a galifrey meta package is created in the packaging-farm with the sole purpose of copying all packages in a single repository. The following line could be added to a virgin Debian GNU/linux lenny source list and should now be equivalent to its counterpart on http://dak.proformatique.com/debian/
deb http://xivo.dachary.org/packaging-farm/gallifrey/gnulinux/debian/i386/lenny/src/ ./ deb-src http://xivo.dachary.org/packaging-farm/gallifrey/gnulinux/debian/i386/lenny/src/ ./
Implementing dependency handling in packaging-farm
Although an i386 repository is now available for the XiVO packages which solely depend on Debian GNU/Linux lenny, it would be tedious to manually arrange the packaging-farm to accomodate for the four level of dependencies. Instead packaging-farm should be modified to handle interdepencies of packages. Although it would be possible to arrange for the other operations to be supported by a specific tool (for instance importing all the packages from a known repository), such an operation is not frequent and the time to properly write such a tool and make sure it works as expected probably outweights the benefit.