VNC behaving weirdly

in flag

I have an Ubuntu-based Docker container (using this image, which is based on this Ubuntu 22.04 image) that I'm VNC'ing into from a Windows machine. I've used a couple of different VNC clients (VNC Viewer and TightVNC) and both exhibit the same behavior. The client area is huge, mostly black, with a low resolution terminal at the top-left:

Screenshot of VNC client

(note the scroll bar on the right. Scrolling down just shows an enormous amount of empty, black space).

Interacting with the terminal is working, though presenting other problems. I think the weird VNC behavior might be indicative of something not being quite right in the image itself, which may in turn lead to clues as to why the other problems are occurring.

I've tried playing around with the VNC picture and scaling options, but it kind of does what you'd expect. If I tell it to scale to fit the window I see this:

Screenshot of VNC client scaled to fit window

That's the terminal at the top, with what appears to be another one part-way down (though I don't see this when I turn scaling off and simply scroll down).

Can anyone shed any light on what's going on here and how to fix it?

guiverc avatar
cn flag
You've provided no clear details as to what Ubuntu product/release you're asking about? nor what setup you've made. I note a *root* terminal (*the root account is disabled by default*) so is this Ubuntu, or what are you using? What you describe is what I'd expect with a simple/basic Xorg setup (ie. *unconfigured*), where you can change your config/X session via commands; but I gather you're expecting something else? but we don't know what setup/config you're using on your *unstated* release, so how can we currently help?
me-- avatar
in flag
@guiverc Apologies. It's based on the official Ubuntu image `ubuntu:22.04`. Will update Q
zwets avatar
us flag
It's _very_ loosely based on Ubuntu 22.04. :)
us flag

The container you are using was built to include the package x11vnc:

# Step 32 in the container build
RUN /bin/sh -c apt-get install -y --no-install-recommends x11vnc ...

Its package description is "VNC server to allow remote access to an existing X session", and that is pretty much what your screenshots show: an empty X11 session.

Apart from that package, and a bunch of mythtv packages (from the mythbuntu PPA) and installation scripts there is very little Ubuntu as we know it (i.e. Desktop or Server) in the image.

I would suggest contacting the provider of the Docker image for support. I noticed that the name of the Docker image is "mythbackend:setup", so it's more of an appliance than an Ubuntu system.

in flag

OK, the problem was just missing documentation. The setup runs as root, so there is no need to be a member of the group. One can hit "No" when prompted to add to the group, then hit "Yes" to disable the warning. From there, setup runs fine.

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