Monthly Archives: September 2011

Using Arkose for development and packaging

Since I last reinstalled my laptop, I try to keep my usually insanely long list of installed packages to a bare minimum. I’d usually have hundreds if not thousands of libraries and development packages as these are required by a bunch of packages I maintain or code I work on.

To achieve this and still be as productive as before (if not more), I’m using arkose quite a lot to generate temporary dev/build environment that are wiped as soon as I close the shell.
This helps maintain the number of extra libraries to a minimum, avoiding situations where something mysteriously works fine on my laptop but not on another machine and avoids the maintenance needed when dealing with chroots.

Arkose used to install libdbus-1-dev

An example of this is when I’m working on ubiquity (the Ubuntu graphical installer).
Ubiquity depends on quite a few libraries and development packages that are required even if you just want to build its source package.

So having arkose installed on my system, I usually start working on a bug with:

sudo arkose -n -h -c "cd $PWD; $SHELL"

You can make that an alias if you use it quite often. At this point, you’ll see your shell showing a different hostname, like “arkose-tmpaF9yqa”, that’s how you know you’re in a container.
The command above creates a new container using copy-on-write for all the file system but your home directory and lets the container access the network without any restriction.

I then install all the packages I’ll need to work

sudo apt-get build-dep ubiquity

Then work as usual in that container, run debuild, dput, … everything should work as usual as it has direct access to my home directory.

Once I’m done and I don’t need all these packages anymore, I just exit that shell and all the changes done outside of /home will be lost.

Posted in Arkose, Canonical voices, LXC, Planet Ubuntu | Tagged | 17 Comments

Install multiple version of the same package and avoid filesystem conflicts

One common problem with installing out-of-distro packages is that you can’t really be sure they won’t mess with your existing system. Most common problems include having them replace existing files or add plugins that you don’t really want or that will end up crashing other applications.

There’s also the case where you may want to get the all new and shiny version of a software but still keep the old version around as some other users may prefer it or other software may depend on it. The current way of doing that is by spending quite a bit of time packaging the version to avoid any filesystem conflicts, this works but is usually quite painful to do.

So a few weeks ago I quickly hacked together a debhelper script called dh_ubuntuarb that runs at the end of the package build process and moves all the content to /opt/<package name> except for .desktop entries that are renamed to be arb-<package name>-<original name> and altered to run using “arb-wrapper”.

arb-wrapper uses an overlay fuse filesystem to create a view where the content of the package is stacked on top your root filesystem, it then uses fakechroot to make the app believe it’s running in /.

The software and the user shouldn’t notice any difference and doing that solves the whole file system conflicts and allows you to run as many version of the package as you want (it just needs to have a different name). This is particularly handy for automated packaging where you don’t want to spend too much time reviewing the packages and for cases where you want to run multiple version of the same package.

This code is very much proof of concept and might be extended and uploaded to the archive for Ubuntu 12.04. For now it can be tested in a PPA:

Below is an example using “lightyears” from the arb-testing PPA:
# Build lightyear with dh_ubuntuarb and installed it on my system
# then created an empty /tmp/test directory
stgraber@castiana:~$ ls /tmp/test
stgraber@castiana:~$ which lightyears

# Now starting the overlay of my / and /opt/
stgraber@castiana:~$ arb-wrapper lightyears bash

# Checking that lightyears is indeed accessible now
stgraber@castiana:/$ which lightyears

# Creating some data
stgraber@castiana:/$ touch /tmp/test/me

# Exiting the environment
stgraber@castiana:/$ exit

# And the file is still there
stgraber@castiana:~$ ls /tmp/test/me

Installing the “lightyears” package from that PPA will add a desktop entry called arb-lightyears_lightyears.desktop in /usr/share/applications and that’s the only change that will happen outside of /opt/ This software will appear in your menu as usual and when you click on it will use the arb-wrapper to start just as you’d expect it to.

I’m very much interested in hearing ideas of possible use cases for that kind of things in Ubuntu and hope to be able to discuss it more in Orlando at the next UDS.
I think we should be able to get some pretty exciting things going using that kind of tools and containers like arkose provides.

UPDATE: The “arb” in the script names stands for the Ubuntu App Review Board which was the initial reason for doing that work as an easy way of getting a package to match our packaging requirements.

Posted in Canonical voices, Planet Ubuntu | 3 Comments

Help translate Edubuntu 11.10

Now that the release of (Edu|Ku|Lu|Myth|Xu|U)buntu is just a month or so away and all the UIs aren’t supposed to change till release, it’s time to help making sure everything is translated.

One of my goals for Edubuntu 11.10 was to have all our custom components (installer steps, LTSP, Arkose, …) supporting translations as early as possible so people can just boot our DVD and get a fully translated environment right out of the box (yes, we ship all the langpacks).

While that goal has been relatively easily reached, Edubuntu still needs some help getting everything translated. Here are a few links to some parts of Edubuntu that need some love:

All of the above weren’t translated at all in Edubuntu 11.04 so they definitely need help to get as good as the rest of the distro.

More information on helping translating Ubuntu (not only Edubuntu) can be found on the wiki:


Posted in Canonical voices, Edubuntu, Planet Ubuntu | 1 Comment