Ubuntu Desktop with LXC container

When wanting to use desktop applications via a container, it is helpful to be able to set up the container to have a desktop environment accessible via VNC.

I started this by using the Proxmox template for Ubuntu 22.04. At this time of writing, the 24.04 template is more than a bit ‘iffy’ and doesn’t work well. So we’ll go with 22.04 for it.

To give credit where credit is due, I found multiple sources for this information. References are below for what I found.

Install the template on a container. About 4GB RAM and a few processor cores is good.

Once ready, configure the system as you wish (e.g. add a user, set up VIM defaults) and run the following to make sure things are up to date:

apt-get update ; apt -y upgrade

Then to install the desktop software

Desktop software

To start with installing the desktop and VNC software you will need to do the following:

apt install xfce4 xfce4-goodies xorg dbus-x11 x11-xserver-utils

VNC for Multiple users

I am using tigerVNC and wanted it to be able to run on a per-user basis. I started by installing the software.

apt install tigervnc-standalone-server gdm3

For most uses, having the VNC service run all the time with a user is fine but I wanted to have things set up so that I would only be running the X desktop services when I actually log in to it. Then the container/VM can just sit there otherwise with relatively no processes running. To that end I made the following systemd unit files:

/etc/systemd/system/xvnc.socket

[Unit]
Description=XVNC Server on port 5900

[Socket]
ListenStream=5900
Accept=yes

[Install]
WantedBy=sockets.target

/etc/systemd/system/xvnc@.service (make sure to get the '@' symbol in there)

[Unit]
Description=Daemon for each XVNC connection

[Service]
ExecStart=-/usr/bin/Xvnc -inetd -query localhost -geometry 2000x1200 -depth 24 -once -SecurityTypes=None
User=nobody
StandardInput=socket
StandardError=syslog

Then run:

systemctl enable xvnc.socket

To set the default session to XFCE4 you will need to run:

update-alternatives --set x-session-manager /usr/bin/xfce4-session

However, that seems to sometimes not work so you might want to look at the file /var/lib/AccountsService/users/{user} where {user} is your username you made earlier. In that file is a setting for ‘session’

Reboot your container/VM at this time.

Using your favorite VNC software you should be able to VNC to your system and see the gdm greeter. You can then log in and X services will start. Note too that you can select the gear-wheel icon on the gdm greeter bottom-right and select what session type to use.

To note, I did have some awful trouble with more complicated desktop environments since they didn’t seem to like being installed within a containerized environment. It kept blocking/hanging on installing if any of the ‘-desktop’ packages were installed.