Joseph Herlant
version 1.0.0, 2014-06-21 : Initial version

1. Introduction

Experimental distribution is not a complete distribution, so you can’t specify it when you create an sbuild chroot. I didn’t find a complete documentation on how to do that so here’s mine based on my own experience.

For more informations about the experimental repository, see:

2. Creating chroot

In my configuration, I had already a sbuild environment configured for unstable. For more informations about how to configurei a basic sbuild environement, see:

So, first add a new chroot with a tarball named experimental-$arch and with "unstable" as target.

sudo sbuild-createchroot \
  --make-sbuild-tarball=/var/lib/sbuild/experimental-amd64.tar.gz \
  unstable `mktemp -d`

Now, you need to change the distribution in the chroot configuration file. Those files are located in "/etc/schroot/chroot.d/" directory. Edit each until you find the right one (the one with the "file" field having the name you gave to the tarball in the creation command).

Mine was:

$ cat /etc/schroot/chroot.d/unstable-amd64-sbuild-i6snHD
description=Debian unstable/amd64 autobuilder

Edit it and replace the "unstable" sentences with "experimental". You can do it with the following command (replacing the file name with yours:

sudo sed 's/unstable/experimental/g' -i /etc/schroot/chroot.d/unstable-amd64-sbuild-i6snHD

You can also change the name of the file for a more explicit one:

sudo mv /etc/schroot/chroot.d/unstable-amd64-sbuild-i6snHD /etc/schroot/chroot.d/experimental-amd64-sbuild-i6snHD

Now the file you changed should look like this:

$ cat /etc/schroot/chroot.d/experimental-amd64-sbuild-i6snHD
description=Debian experimental/amd64 autobuilder

3. Configuring your chroot for experimental

First, to find your chroot, you have to use the schroot -l | grep sbuild command. This should display something like:

$ schroot -l | grep sbuild

When you use the "source:$distribution-$architecture-sbuild", all the changes you make to the chroot while editing it with sbuild-shell are saved on exit.

When you use the "chroot:$distribution-$architecture-sbuild", all the changes you make to the chroot while editing it with sbuild-shell are lost on exit.

So here you need to make the experimental repository available in the chroot and you need it saved for further usage. Here we will ad the experimental repo to the newly created /etc/apt/sources.list.d/experimental.list file, the pin the unstable distribution to a higher priority to ensure the build environment will be able to find a package and pin the experimental distribution to a lower one (doing the other way should not work - at least it didn’t for me). Which gives:

$ sudo sbuild-shell source:experimental-amd64-sbuild
I: /bin/sh
# cat /etc/apt/sources.list
deb unstable main
deb-src unstable main
# ls -l /etc/apt/sources.list.d
total 0
# ls -l /etc/apt/preferences*
total 0
# echo "deb experimental main" > /etc/apt/sources.list.d/experimental.list
# echo "deb-src experimental main" >> /etc/apt/sources.list.d/experimental.list
# echo "Package: *\nPin: release a=unstable\nPin-Priority:900" > /etc/apt/preferences.d/unstable.pref
# echo "Package: *\nPin: release a=experimental\nPin-Priority:800" > /etc/apt/preferences.d/experimental.pref
# exit

Then update your chroot (this does apt-get update, apt-get dist-upgrade, apt-get clean, apt-get autoclean and apt-get autoremove):

sudo sbuild-update -udcar experimental-amd64-sbuild

Now that you have an environment configured, you should backup your tarball:

sudo cp /var/lib/sbuild/experimental-amd64.tar.gz /var/lib/sbuild/experimental-amd64.tar.gz.clean

4. Building your package

If you want, you can test your chroot as a sandbox (when exiting this shell all your changes will be lost) using:

sudo sbuild-shell chroot:experimental-amd64-sbuild

Before building your package with sbuild, there’s one last thing you need to do: install all the dependencies needed by your package that are AVAILABLE in the experimental repository (not only the one whose version is needed to be at least the experimental version). You need to do that in your chroot and ensure that the changes are saved. but first, you should ensure that you made a backup of the chroot tarball as explained in the previous step.

You don’t need to install the dependencies of your package that are only available in the unstable repository.

In my case, the dependencies that needed to be at least the version matching experimental were only gnome-common and libcanberra-dev, but other dependencies of my package were available in the experimental repository, so I needed to install them also. Which gave (don’t forget the -t experimental in the apt-get -t experimental install ... command!):

$ sudo sbuild-shell source:experimental-amd64-sbuild
# apt-get -t experimental install gnome-common libcanberra-dev libglib2.0-dev libgnome-desktop-3-dev libgstreamer1.0-dev libupower-glib-dev
# exit

Then ensure the chroot is up-to-date using:

sudo sbuild-update -udcar experimental-amd64-sbuild

And now you can build your package!

cd /path/to/my/package/source
sbuild -d experimental -c experimental-amd64-sbuild

5. Cleaning up the chroot

When you’re done with this package, don’t forget to revert your changes made by the previous step in the experimental chroot by copying the clean tarball back:

sudo cp /var/lib/sbuild/experimental-amd64.tar.gz.clean /var/lib/sbuild/experimental-amd64.tar.gz