I've got kwin_wayland + plasmashell (wayland) running in a container (bugs included)

[Sebastian Grüner]

hey all,

I've been fiddling around wit lxc on a smartphone the other week, did
some reading and thought I'd try out some ideas with kwin_wayland.
This is one of your proposals for this years GSOC projects at KDE [1],
and I know my approach is different from what is explained there.
Nevertheless I'd like to share my initial hack with you, in case anyone
wants to pursue this further.
Long story short: I copied random bits and pieces of the web and got
kwin_wayland and plasmashell (via startplasmacompositor) running in a
containerized environment with native hardware acceleration, no llvmpipe
needed :-). (I used systemd-nspawn, docker and lxc should work as well,
haven't tried this though).

Here is what I've done:
Get a rootfs of your favorite distro:
- I use Opensuse Tumbleweed since I am familiar with this. (KDE
Frameworks 5.20, Plasma 5.5.95)
- I set up Debian unstable as well, which worked, but this uses old KDE
packages (debootstrap)
- I tried Ubuntu Xenial (debootstrap), weston works with native hw, but
kwin_wayland won't start up.

Systemd comes with a minimal container tool, systemd-nspawn [2], which
is described as similar to a chroot and quite easy to use. With this one
can just switch into the rootfs:

sudo systemd-nspawn -D $ROOTFSDIRECTORY/

systemd-nspawn has quite a lot of command line switches, you can set
environment variables and bind-mount specific directories for example.
So why not just bind-mount the device-node of my graphics-card?
here we go:

xhost +local:

sudo systemd-nspawn --setenv=DISPLAY=:0 \
--setenv=XAUTHORITY=~/.Xauthority \
--setenv=XDG_RUNTIME_DIR=/run/user/1000 \
--bind-ro=$HOME/.Xauthority:/root/.Xauthority \
--bind=/run/user/1000/:/run/user/1000 \
--bind=/tmp/.X11-unix \
--bind=/dev/shm:/dev/shm \
--bind=/dev/dri/card0:/dev/dri/card0 \
-D suse/ kwin_wayland --libinput --xwayland --drm --windowed "konsole
--platform wayland"

Initially I tried weston: to do this just change the command at the very
end. If you change the command to startplasmacompositor the Plasma
desktop starts up. In order to make Plasma useable and avoid loops for
kscreen, powerdevil you need Dbus, so I just did bind mount my
bus-socket with

--bind=/run/dbus/system_bus_socket:/run/dbus/system_bus_socket

It should be somehow possible to run the dbus-daemon from within the
container.

There is probably a lot of stuff that could be improved upon, but I got
plasmashell in a container up and running!
If the container hangs/crashes you can terminate it from a different tty
with machinectl [3].

I hope you like this. :-)

Sebastian

[1]
https://community.kde.org/GSoC/2016/Ideas#Project:_Running_KWin.2FWayland_in_a_Docker_container
[2] https://www.freedesktop.org/software/systemd/man/systemd-nspawn.html
[3] https://www.freedesktop.org/software/systemd/man/machinectl.html