This page describes how to compile a backport in the "proper" way, one which tries to respect the rules for the backports.

This assumes you will build a backport that will be uploaded to the official backports repository. For simpler recipes, look for SimpleBackportCreation for your own informal backports or AutomateBackports for your own personal backporting archive.

Retrieve the Package Source

Backports for a release, for almost all cases, must be prepared from the subsequent release. There are multiple ways to retrieve a package source. A simple way is to use dget (from the devscripts package)` on the URL for the desired package's dsc file:

If you find your package listing by searching on https://packages.debian.org for the appropriate source distribution (Testing, in the case of Stable backports), you will see a link to its dsc file. The following command will retrieve the source package and extract it for you:

More efficient workflows for ongoing maintenance of the backport will make use of the maintainer's packaging VCS and/or dgit instead.

Modify the package as needed

To make a proper backport, you need to modify the package according to the rules. A simpler version:

This is just a summary of the technical aspects of the rules. It is really important that you read up on the rules and follow them.

Build in a minimal environment

Using sbuild

Preparation for first use

The sbuild page provides guidance for setting up sbuild. Some backports-specific notes are mentioned here.

The Examples section of sbuild-createchroot(8) specifically shows how to create a chroot for the Stable release that also allows access to Stable-backports (which may be needed to fulfill dependencies in the backport you intend to prepare).

Building your backported package

From the top-level directory of the backported source package, you should be able to build as follows:

Where <last-main-version> is the version of the most recent backport or Stable released version (as recommended in the Backports rules)

The aptitude build dependency resolver is needed in order to be able to pull packages from Stable-backports as needed (which will only happen if the build-dependencies cannot be met from Stable).

Building multi-dependency packages

If your package requires others to be backported first, you can build them as described above and then use them from your local file system without having to manually set up a temporary APT repository. Simply pass --extra-package <absolute-path-to-deb-file> in your call to sbuild.

Using pbuilder

/!\ This section needs a major update, in its current state it has a lot of mistakes and thus currently isn't about official backports anymore.

Your first step is to configure pbuilder and, optionally, cowbuilder. The remaining of this howto will assume you will use cowbuilder, as this is what is in use here and is more efficient. We also like to use git-buildpackage to avoid building a .dsc file first, so to build straight from the source.

A full pbuilder or cowbuilder is beyond the scope of this manual, but there are specific issues you should not miss here. See git-pbuilder for details of use of cowbuilder/pbuilder with git-buildpackage.

Installing the toolchain

apt-get install cowbuilder pbuilder

Building for different distributions

Then enable pbuilder to build for different distributions easily, by following those instructions.

At this point you should be able to build a package using:

DIST=jessie ARCH=amd64 pbuilder build --debbuildopts "-sa -v1.0" foo.dsc

With git-buildpackage this becomes:

cd package
DIST=jessie ARCH=amd64 git-buildpackage --git-builder=git-pbuilder  -sa -v1.0

Note that this option can be written to your ~/.gbp.conf file as such: builder = /usr/bin/git-pbuilder.

Another example, with cowbuilder:

DIST=wheezy ARCH=i386 pdebuild --pbuilder cowbuilder --debbuildopts "-sa -v1.0"

Advanced: Building multi-dependency packages

At this point you are able to build and upload backports of existing packages easily. The tricky part comes up when you have multiple dependencies to upload at once. pbuilder chroots do not use packages from backports by default, so that's the first thing we need to fix. Add this to your pbuilderrc:

OTHERMIRROR="deb http://www.backports.org/debian/ $DIST-backports main"

Then update the chroot with the new sources.list line:

sudo DIST=jessie ARCH=amd64 cowbuilder --update --override-config

Then you could build the packages one at a time: backport one, upload it, wait for it to show up in the backports archive, build the second one, etc. But this is really time consuming and could take a long time for big package suites. It could also mean a lot of dependent packages be uploaded to backports while the package that needs it is not there, which is bad practice.

What you need is to be able to use the packages you're building locally in the chroot. This is again described in the PbuilderTricks page, but we'll show our own way here.

Add this to your pbuilderrc:

OTHERMIRROR="deb http://www.backports.org/debian/ $DIST-backports main|deb file:///home/anarcat/dist/build-area/ ./"
HOOKDIR=/usr/lib/pbuilder/hooks
BINDMOUNTS="/home"

The above assumes you are building your packages in /home/anarcat/dist/package and the build results end up in /home/anarcat/dist/build-area/. This can be freely changed, but it will only work if it is under the BINDMOUNTS.

Then you need to add a hook that will run apt-get update before the package is built, in /usr/lib/pbuilder/hooks/D90update:

/usr/bin/apt-get update

The HOOKDIR variable can be changed if you want to put your hook file somewhere else, but the file name is important.

Then the only bit missing is making sure the /home/anarcat/dist/build-area/ directory is a valid archive. Other howtos make that part of the hook, but since we are not running as root (see below), this is not practical for us. We simply use the following command on a as-needed basis:

dpkg-scanpackages . /dev/null | bzip2 -c  > Packages.bz2

It is in the following makefile to make things easier:

all: Packages.bz2 Sources.bz2

Packages.bz2::
        dpkg-scanpackages . /dev/null | bzip2 -c  > Packages.bz2

Sources.bz2::
        dpkg-scansources . /dev/null | bzip2 -c  > Sources.bz2

Note that the above will fail because it's missing the SecureApt key. See AutomateBackports for another example which may resolve this.

Other tricks

We have found the following options to be useful in pbuilderrc:

PDEBUILD_PBUILDER="cowbuilder"

BUILDUSERID="500"
BUILDUSERNAME="anarcat-pbuilder"

AUTO_DEBSIGN=yes

This is the ~/.gbp.conf (git-buildpackage config):

[DEFAULT]
# tell git-buildpackage howto clean the source tree
cleaner = fakeroot debian/rules clean
postbuild = lintian $GBP_CHANGES_FILE
# this is how we invoke pbuilder, arguments passed to git-buildpackage will be
# passed to dpkg-buildpackge in the chroot
builder = /usr/bin/git-pbuilder

[git-buildpackage]
export-dir = ../build-area/

[git-import-orig]
dch = False

Self-contained example for Apache 2.4

STABLE=wheezy
TESTING=jessie

# Prepare local repo
mkdir -p /usr/src/backports/$STABLE/
touch /usr/src/backports/$STABLE/Packages
cat <<'EOF' > /usr/src/backports/$STABLE/D70results
#!/bin/bash
# Make sure local repo is updated before building
cd /usr/src/backports/$STABLE/
dpkg-scanpackages . /dev/null > Packages
apt-get update
EOF
chmod 755 /usr/src/backports/$STABLE/D70results

# Create initial environment
sudo pbuilder --create --basetgz /var/cache/pbuilder/base-$STABLE-bpo.tar.gz \
  --distribution $STABLE \
  --othermirror "deb http://security.debian.org/ $STABLE/updates main|deb http://http.debian.net/debian $STABLE-backports main|deb [trusted=yes] file:///usr/src/backports/$STABLE ./" \
  --bindmounts /usr/src/backports/$STABLE/
# Update regularly:
# sudo pbuilder --update --basetgz /var/cache/pbuilder/base-$STABLE-bpo.tar.gz --bindmounts /usr/src/backports/$STABLE/

# Add source for 'apt-get source'
echo "deb-src http://ftp.fr.debian.org/debian/ $TESTING main" \
  | sudo tee /etc/apt/sources.list.d/$TESTING-src.list
sudo apt-get update

# Setup identity
export DEBEMAIL="you@debian.org"
export DEBFULLNAME="Your Name"

# Configure build
#export DEB_BUILD_OPTIONS="parallel=$(nproc) nocheck"
export DEB_BUILD_OPTIONS="parallel=$(nproc)"

# Create a working directory for sources
mkdir /usr/src/backports/sources/
cd /usr/src/backports/sources/

# Dependencies to add in our local repo
apt-get source apr/$TESTING
(
    cd apr-1.5.1/
    dch --bpo "No changes."
    pdebuild --debbuildopts '-v1.4.6-3+deb7u1' \
        --use-pdebuild-internal --buildresult /usr/src/backports/$STABLE/ \
        --pbuildersatisfydepends /usr/lib/pbuilder/pbuilder-satisfydepends-experimental \
        -- --basetgz /var/cache/pbuilder/base-$STABLE-bpo.tar.gz \
           --bindmounts /usr/src/backports/$STABLE/ \
           --hookdir /usr/src/backports/$STABLE/
)
apt-get source apr-util/$TESTING
(
    cd apr-util-1.5.3/
    dch --bpo "No changes."
    pdebuild --debbuildopts '-v1.4.1-3' \
        --use-pdebuild-internal --buildresult /usr/src/backports/$STABLE/ \
        --pbuildersatisfydepends /usr/lib/pbuilder/pbuilder-satisfydepends-experimental \
        -- --basetgz /var/cache/pbuilder/base-$STABLE-bpo.tar.gz \
           --bindmounts /usr/src/backports/$STABLE/ \
           --hookdir /usr/src/backports/$STABLE/
)

# Apache 2.4 itself
apt-get source apache2/$TESTING
(
    cd apache2-2.4.10/
    dch --bpo "Note: depends on backported libapr."
    pdebuild --debbuildopts '-v2.2.22-13+deb7u3' \
        --use-pdebuild-internal --buildresult /usr/src/backports/$STABLE/ \
        --pbuildersatisfydepends /usr/lib/pbuilder/pbuilder-satisfydepends-experimental \
        -- --basetgz /var/cache/pbuilder/base-$STABLE-bpo.tar.gz \
           --bindmounts /usr/src/backports/$STABLE/ \
           --hookdir /usr/src/backports/$STABLE/
)

# Sadly there's no hook to do that *after* the packages are installed in --buildresult
(cd /usr/src/backports/$STABLE && dpkg-scanpackages . /dev/null > Packages)


# Test
sudo pbuilder --login --basetgz /var/cache/pbuilder/base-$STABLE-bpo.tar.gz --bindmounts /usr/src/backports/$STABLE/
/usr/src/backports/$STABLE/D70results
apt-get install apache2 ...


# Publish to official archive
cd /usr/src/backports/$STABLE/
debsign *.changes -k YOUR_KEYID
dput *.changes

If something goes wrong and you need to test manually:

sudo pbuilder --login --basetgz /var/cache/pbuilder/base-$STABLE-bpo.tar.gz --bindmounts /usr/src/backports
apt-get update
cd /usr/src/backports/sources/apache2-2.4.10/
apt-get install pbuilder devscripts fakeroot
/usr/lib/pbuilder/pbuilder-satisfydepends-experimental
debuild ...

Notes:

Uploading the backport

Use dput (≥ 0.9.6.3+nmu2) or dput-ng to upload the resulting package (just like a regular package upload).

See also



CategoryPackaging