Start lubuntu Desktop in Docker

During my summer holidays, I've watched this video: Full Ubuntu GUI in a Container Displayed on Windows (XServer) and, of course, I wanted to play with it.

The idea is to start a Lubuntu Desktop distribution as a Docker container. Lubuntu is a lightweight Ubuntu distribution designed to be more resource-efficient than the standard Ubuntu.

Using Docker and Windows X Server, we'll be able to play with Lubuntu just like any other container, i.e. play and drop without any impact on our host. Ideal for learning purposes then.

This is the "whole desktop" variant. For a single application, see Docker - Run Graphical User Interfaces - Firefox, Chrome & GIMP; and if you'd rather avoid installing an X Server at all, Docker - Running some GUI interfaces in the browser displays them in a browser tab instead.

Result​

A full Lubuntu desktop, running inside a Docker container, displayed on the Windows host — no VM, no dual-boot, no trace left once you throw the container away.

Why it works​

• Docker gives us a disposable environment: the whole desktop lives in a container, so nothing touches the host — drop the container and it's gone as if it never existed.
• Windows X Server is what actually renders the display: the container sends its GUI output to the X server running on Windows, which draws it on screen.

I encourage you to watch the video Full Ubuntu GUI in a Container Displayed on Windows (XServer).

Step 1 - Create the Dockerfile​

There is just one file to create called Dockerfile and with this content:

FROM ubuntu:latest

RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y lubuntu-desktop lightdm && \?
    rm -rf /var/lib/apt/lists/*?

RUN rm -f /run/reboot-required*?
RUN echo "/usr/sbin/lightdm" > /etc/X11/default-display-manager?
RUN printf '%s\n' \
    '[LightDM]' \
    '[Seat:*]' \
    'type=xremote' \
    'xserver-hostname=host.docker.internal' \
    'xserver-display-number=0' \
    'autologin-user=root' \
    'autologin-user-timeout=0' \
    'autologin-session=Lubuntu' \
    > /etc/lightdm/lightdm.conf.d/lightdm.conf

ENV DISPLAY=host.docker.internal:0.0?

CMD service dbus start ; service lightdm start?

Build the image by running docker build --tag cavo789/lubuntu . (remember to replace cavo789 with your own username).

Step 2 - Install Windows X Server​

Building the image will take a few minutes (the final image will be around 3 GB).

During the creation of the image, please install Windows X Server. It's just a .exe to install on your Windows machine.

Once installed, run the program. On the first screen, as explained in the video, select One large window; click on Next and keep all default values then click on Finish on the last screen.

By clicking on Finish you'll get a black screen. It's normal.

Step 3 - Start the container​

Run your container by starting docker run -t cavo789/lubuntu and wait, wait and wait again. If you got warnings on the console, don't worry and still wait.

You may have to wait a minute before you start to see the Linux Lubuntu desktop, and then you'll still need to wait because the operating system is loading and initializing (since it's the first time you start it) — you'll get the desktop shown at the top of this article.

Conclusion​

Do you realize that we've installed a Linux distribution and launched its GUI as a container? In fact, it's like installing a new PC.

Of course, we'd have to go further than that, e.g. to keep data persistent (via volumes).