Docker, X11 fails to open display

I have a docker container and I want to run an app that requires X11. I want to expose that in the host. This is actually working well in a notebook but fails in a desktop.

More info:

I am launching docker with the correct arguments:

    docker run -it --rm \
    --privileged \
    -e DISPLAY \
    -v /tmp/.X11-unix:/tmp/.X11-unix:ro \
    .... not related options ....
    $(DOCKER_IMAGE) \
    xclock

In a notebook (Ubuntu 19.10) works great BUT when I try the same in a desktop (Ubuntu 19.10), I get Error: Can't open display: :1

There is somehow something different and I cannot find out what the difference is.

I have already:

• Disabled access control xhost +
• There is no ~/.Xauthority file
• No firewall enabled
• Containers are identical (both computers download the image from Dockerhub).
• This is not about SSH at all, so X11 forwarding is not relevant.
• Both computers are using X11 (no wayland involved)

I have noticed that notebook uses :0 and desktop :1 but I don't think that is relevant.

Question: Are there any log files that I could look at? Any tips on debugging the issue?

Solution 1:

Had the exact same problem with a laptop. It worked for me if I added --net=host. Never bothered to figure out why.