Ubuntu Kiosk

This post is a work in progress. I’ll update it as I tweak the solution.

Last Wednesday I was helping a friend build a Kiosk. We tried to follow https://thepcspy.com/read/building-a-kiosk-computer-ubuntu-1404-chrome/ but it didn’t work. It turns out between using the wrong version of ubuntu (16.04 instead of 14.04) and doing it in a virtual machine, we were all messed up.

There has to be a better way.

There is a secret to debian/ubuntu packages. If you aren’t trying to get them included in debian/ubuntu, you can break most of the rules and get them to do whatever you want. I figured I should be able to use this and make creating a kiosk as easy as apt install kiosk

TL;DR: you can try this by running these two commands on a new ubuntu-server installation:

add-apt-repository ppa:evarlast/kiosk
apt install --no-install-recommends kioskme

The rest of the post describes how I did this.

First, I’m going to create a new PPA on launchpad just for this, so that a user can `add-apt-repository ppa:evarlast/kiosk`

I visit https://launchpad.net/~/+activate-ppa and fill in the fields with kiosk and click activate.

Next, I start a new deb. I may as well build it from source. There might be a better way, but I’ve gotten to know dh (debhelper) a bit, so I’m going to use it.

$ mkdir kioskme ; cd kioskme
$ cat > Makefile
<tab>echo noop
<tab>install -d 755 ${DESTDIR}/usr/bin
<tab>install -m 755 kioskme ${DESTDIR}/usr/bin/kioskme
$ cat > kioskme
xset -dpms
xset s off 
openbox-session & 
while true; do 
  rm -rf ~/.{config,cache}/chromium/ 
  chromium-browser --kiosk --no-first-run 'http://duckduckgo.com' 

Now debianize this script directory using dh_make:

dh_make -p kioskme_0.0.0 --createorig -s

Now customize the deb with a service, preinst for user creation and some dependencies:

$ cat > debian/service

ExecStart=/usr/bin/startx /etc/X11/Xsession /usr/bin/kioskme
$ cat > debian/preinst

set -e

. /usr/share/debconf/confmodule

case "$1" in
 if ! getent group kioskme >/dev/null; then
 addgroup --system kioskme >/dev/null
 if ! getent passwd kioskme >/dev/null; then
 adduser \
 --system \
 --disabled-login \
 --ingroup kioskme \
 --gecos kioskme \
 --shell /bin/false \
 kioskme >/dev/null
 mkdir -p /var/log/kioskme
 chown kioskme:kioskme /var/log/kioskme
 setfacl -m u:kioskme:rw /dev/tty0 /dev/tty7


 echo "preinst called with unknown argument \`$1'" >&2
 exit 1

# dh_installdeb will replace this with shell code automatically
# generated by other debhelper scripts.


exit 0

Alright, maybe that preinst is a bit big. I copy it around and fill it out like a template for services I put into debs.

Now edit the debian/control file to add dependencies, change the section to utils, fill in whatever else you want, set Depends to look like this:

Depends: ${shlibs:Depends}, ${misc:Depends}, Xorg, openbox, chromium-browser, pulseaudio

Now create the deb:

fakeroot debian/rules clean build binary

To test the deb, I copy it to a fresh ubuntu server install and dpkg -i to install it. I get a bunch of errors because dpkg -i doesn’t resolve dependencies, but I run apt install -f and the dependencies are installed.

Once I tested and tweaked and got things working, I updated the tarball `tar -Jcf ../kioskme_0.0.0-0.orig.tar.xz -C ..  –exclude=’debian’ kioskme` and I used dpkg-buildpackage -S to build a source package and then I used dput ppa:evarlast/kiosk ../kioskme_0.0.0-1_source.changes to upload to PPA.

Now, this still does not work in a VM. Ubuntu desktop installer must do some magic to make X work in a virtual machine with a driver which works with VMWare, VirtualBox, or Parallels.


Version from debian/changelog

Almost two years ago I did some scripting of updating debian/changelog and building a package to enable a CI environment for some software. I wanted to parse the changelog correctly and so I copied and changed some perl from the source of dpkg-buildpackage. This turned out to be the wrong solution.

There is a nice tool called dpkg-parsechangelog. You can get just the version for use in scripts with this simple awk:

dpkg-parsechangelog | awk ‘/Version/ { print $2 }’

I didn’t even think to write about it until I ran across someone else who’d written some perl to do exactly the same thing. Dear world, we need to stop reinventing this wheel.