Hacking on Ubiquity, the setup
written on Tuesday, April 30, 2013
Working on Ubiquity, the Kubuntu installer, is not trivial, or at least it was not for me. This article describes the setup I ended up using, so that I do not waste time on my next Ubiquity hacking session. Hopefully it will be useful to others interested in working on Ubiquity.
This article was originally a part of my previous Ubiquity article, but I decided to split it as the audience is not the same.
Setting everything up
I learned the hard way the preferred way to test Ubiquity is to run your code from within a live Kubuntu session. This is necessary because the installer needs the ISO file system to complete, otherwise it fails when you are done answering questions.
The quick and dirty way to get stuff done is to edit files in
/usr from within
the live Kubuntu session, then copy them back to your checkout of Ubiquity
source code. Quick but dirty, and error prone.
The setup I ended up with looks like this:
- Start live ISO in a VM, tweak the VM environment
- Edit code on host
- Push changes from host to VM
- While broken, goto 2
- Commit changes, file merge request
Get the code and tools
First, setup a base dir. This dir is going to contain 3 repositories: the source for Ubiquity itself, the source for Ubiquity slideshow and a set of scripts I put together.
Get the repositories:
cd src/ubiquity bzr clone lp:ubiquity code bzr clone lp:ubiquity-slideshow-ubuntu slideshow bzr clone lp:~agateau/+junk/ubiquity-scripts scripts
Setting up a VM to accept our code
I use VirtualBox to run this live session on my development machine. I push code from the host to the VM using rsync over ssh, because I can never get VirtualBox Shared Folders to work on development versions of Ubuntu :/.
First, download a live ISO from http://cdimage.ubuntu.com/kubuntu/daily-live/current/.
Then, create a Virtualbox VM, adding the live ISO as CDROM.
Now start the VM and after it has finished booting, select "Try Kubuntu".
At this point, we can start to tweak the VM environment.
Note: In the following sections, terminal commands prefixed with
[VM] are meant to
be run inside the VM, while commands prefixed with
[HOST] should be run on the
Open Konsole and create the folder which will contain the code to test:
[VM] mkdir -p src/ubiquity
[VM] sudo apt-get install openssh-server
For some reason, sshd does not start automatically for me and running
start ssh does not help.
sshd by hand shows it misses the
/run/sshd dir. Here is my ugly
Create the missing dir:
[VM] sudo mkdir /run/sshd
sshd by hand.
[VM] sudo /usr/sbin/sshd
Note: One must use the full path to the sshd binary, otherwise it does not start.
Now we need to set a password for the
kubuntu user, otherwise we can't ssh to it:
[VM] sudo passwd kubuntu Enter new UNIX password: Retype new UNIX password:
Before going back to the host, write down the IP address of the VM:
Go back to the host and install your ssh public key in the VM so that you
don't have to enter the password of the
kubuntu user every time you want to
test a change.
[HOST] ssh-copy-id kubuntu@$VM_IP
Check it works:
[HOST] ssh kubuntu@$VM_IP
You should get logged in the VM without entering the password.
Initial installation of our code in the VM
Time to push our code. From the host:
[HOST] ~/src/ubiquity/scripts/rsync-to-vm $VM_IP
Now, switch back to the VM and let's do some final setup. We are going to rename some of Ubiquity dirs to append "-distro" to their name and replace the original dirs with symlinks. Our development version gets its own symlinks as well, suffixed with "-dev". We will then be able to switch from the distro to the dev version and back.
For example, in
/usr/lib/ubiquity, the following changes will be done for the
pluginsis going to be renamed to
- Two symlinks are going to be created:
plugins-dev, pointing to
pluginspointing either to
There are a few dirs to alter, so I created a script to do the work:
[VM] cd ~/src/ubiquity [VM] scripts/setup setup
Note: no need to call
sudo, the script uses it when necessary.
All symlinks have been created. You can check the status with:
[VM] scripts/setup status lrwxrwxrwx 1 root root 14 mars 25 17:22 /usr/lib/ubiquity/plugins -> plugins-distro lrwxrwxrwx 1 root root 15 mars 25 17:22 /usr/lib/ubiquity/ubiquity -> ubiquity-distro lrwxrwxrwx 1 root root 9 mars 25 17:22 /usr/share/ubiquity/qt -> qt-distro lrwxrwxrwx 1 root root 25 mars 25 17:22 /usr/share/ubiquity-slideshow -> ubiquity-slideshow-distro
To switch to our development version, run:
[VM] scripts/setup dev
Symlinks look like this now:
[VM] scripts/setup status lrwxrwxrwx 1 root root 11 mars 25 17:23 /usr/lib/ubiquity/plugins -> plugins-dev lrwxrwxrwx 1 root root 12 mars 25 17:23 /usr/lib/ubiquity/ubiquity -> ubiquity-dev lrwxrwxrwx 1 root root 6 mars 25 17:23 /usr/share/ubiquity/qt -> qt-dev lrwxrwxrwx 1 root root 22 mars 25 17:23 /usr/share/ubiquity-slideshow -> ubiquity-slideshow-dev
We are now ready to work! We can run our version of Ubiquity with:
[VM] ubiquity -d kde_ui
-d switch turns on debug output, which can be found in
Getting some work done
Hack on the host and whenever you want to test your changes, run:
[HOST] scripts/rsync-to-vm $VM_IP
Then switch to the VM and run Ubiquity:
[VM] ubiquity -d kde_ui
Note: Since the setup relies on the code being in
/home/kubuntu/src/ubiquity/slideshow, using Bazaar branches can be problematic.
I recommend the bzr-colo plugin to switch branches in place.
Testing the greeter
The greeter is the screen which appears when you boot the live ISO. It asks you your language, and let you pick between trying or installing Kubuntu.
To quickly test the greeter mode from within the running Plasma session, run ubiquity with the
[VM] ubiquity -d --greeter kde_ui
If you want to test the full thing, you must restart Ubiquity. To do so, switch to a console session (using Host-VM-key + F1) then run these commands:
[VM] sudo -i [VM] stop --no-wait lightdm [VM] stop ubiquity [VM] pkill -9 X [VM] start ubiquity
You probably also want to make sure the greeter does not try to run the GTK+ frontend. ubiquity-dm picks the GTK+ frontend if it is available, and since you now have the source code of Ubiquity installed, the GTK+ frontend is available. For now the hack I use is to rm it:
[VM] rm ~/src/ubiquity/code/ubiquity/frontend/gtk_ui.py
Note that you need to do so everytime you run rsync-to-vm, since it will bring back the
Testing OEM config
Ubiquity can be run in "OEM" mode. In this mode, the installer is split in two steps:
- The installer installs Kubuntu on the hard disk without creating a user.
- When the user boots the system for the first time, he is prompted with user configuration questions.
To test step 1, set the
[VM] UBIQUITY_OEM_USER_CONFIG=1 ubiquity -d kde_ui
To test step 2, create a symlink named
oem-config on the
and start Ubiquity from this script:
[VM] ln -s /usr/lib/ubiquity/bin/ubiquity oem-config [VM] kdesudo ./oem-config -d kde_ui
Note the source of the link is
/usr/bin/ubiquity. The latter is just a wrapper around the former.
If you read this far, then either you are interested in hacking on Ubiquity and I hope this article helps you, or you are an Ubiquity developer and I hope you did not spot too many mistakes. If you find some, please point them out.