Arch Linux

pabloski

Member

Registered: 2007-03-14

Posts: 31

Systend-nspawn strange behaviour

Hi, I am trying to shift from Docker to Nspawn for my containers, but I have a big problem with systemd-nspawn. I have built a test container with Archlinux to try out how to run GUI applications inside containers. To enable Xorg I have followed this guide https://patrickskiba.com/sysytemd-nspaw … spawn.html

The problem is that if I run the container without --boot the applications start without problems ( I have tried cheese and galculator ), but when I run it with --boot ( starting systemd inside the container ) the GUI applications fail with the error message

"Unable to init server: Could not connect: Connection refused"

This is how I run the container

"sudo systemd-nspawn --bind=/tmp/.X11-unix --bind=/dev/shm --bind=/dev/dri --bind=/dev/nvidia0 --bind=/dev/nvidiactl --bind=/dev/nvidia-modeset -E DISPLAY=:0 -UbD ./archTest"

The container image has been built with the chroot method A https://wiki.archlinux.org/index.php/In … g_a_chroot

What I don't understand is why running systemd inside the container makes it stop running GUI applications. The host systems I have tried are Arch and Ubuntu with Wayland.

I have even tried an Ubuntu container, with the same result.

The reason I need to run it with the --boot option is because I want to be able to dynamically run applications inside the container while the container is running. Something like docker exec. And to do it I need to use systemd-run -M container_name. But systemd-run in unable to communicate with the container if itsn't running systemd.

p.s. while investigating the problem, I tried running xhost +local: in the container. Interestingly the error message is

xhost:  unable to open display ""

So it seems the DISPLAY variable is cleared by systemd during the boot phase. A simple "export DISPLAY=:0" solves the problem. But it shouldn't clear the variable in the first place. After all I want to pass it the $DISPLAY value from the host. Ideas?

Last edited by pabloski (2020-12-18 18:02:49)

jonno2002

Member

Registered: 2016-11-21

Posts: 684

Re: Systend-nspawn strange behaviour

add

DISPLAY=:0

to

/etc/environment

inside the container