docker-gui

docker-gui - is the base image for running GUI applications in Docker.

NOTE

It's a crazy idea to run GUI applications in Docker containers, but sometimes there is no other way to run the application on the server or on the current OS.

How to create a new image?

Let's look at an example of creating a new image to run the Chromium browser in Docker.

Create image directory

Create a new directory for the image files anywhere and go to it:

$ mkdir ~/docker-chromium
$ cd ~/docker-chromium

Next, create a directory and file structure as shown below:

.
├── Dockerfile
└── root
    └── etc
        └── s6-overlay
            └── s6-rc.d
                ├── chromium
                │   ├── dependencies
                │   ├── run
                │   └── type
                └── user
                    └── contents.d
                        └── chromium

The image uses the s6-overlay service manager. Therefore, to understand why each directory or file is needed, it is better to refer to the official documentation.

Create service

The file ./root/etc/s6-overlay/s6-rc.d/chromium/run contains the code to start the service (in the example browser). It is recommended to use the execline language:

#!/command/execlineb -P

with-contenv

redirfd -w 2 /dev/null

chromium --no-sandbox --start-maximized

In the ./root/etc/s6-overlay/s6-rc.d/chromium/type file, specify the type of service: longrun - starts at startup, if the service crashes, it will be restarted (the browser cannot be closed =)

longrun

In the ./root/etc/s6-overlay/s6-rc.d/chromium/dependencies file, specify the dependencies on other services (who should be started first), one dependency per line:

openbox

The file ./root/etc/s6-overlay/s6-rc.d/user/contents.d/chromium is empty, it is a link indicating that this service is enabled and should be started.

Dockerfile

Create a new Dockerfile and install the application with all required dependencies, for example:

FROM kyzimaspb/gui

# By default, all services run as a normal user
# To install, you need to switch to superuser
USER root

RUN set -x \
    && apt update \
    && apt install -yq --no-install-recommends chromium \
    && apt-get clean  \
    && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

# Directory containing the description of the service
COPY ./root /

# We return the launch as a normal user
USER user

Build

Build an image file named chromium:

$ docker build -t chromium .

Run in daemon mode

Run the container named chromium_1 in daemon mode and forward the specified ports to the specified ports of the host machine:

$ docker run -d --name chromium_1 \
      -p 5900:5900 \
      --shm-size 2g \
      chromium

Forwarded ports:

5900 - TCP port for connecting VNC clients;

Stop a running container:

$ docker stop chromium_1

Environment Variables

XVFB_RESOLUTION - screen resolution of the virtual X server;
VNC_SERVER_PASSWORD - the password for the VNC server.

Autostart with a password

Automatically start the container at system startup with the password qwe123 to connect to the VNC server:

$ docker run -d --name chromium_1 \
    -p 5900:5900 \
    --shm-size 2g \
    --restart unless-stopped \
    -e VNC_SERVER_PASSWORD=qwe123 \
    chromium

The source code for the example is available in the examples/chromium directory.

Build Arguments

RELEASE - The release name of the Debian distribution. Available values are bullseye-slim, bullseye, buster-slim, buster, stretch-slim, stretch. The default is bullseye-slim.
UID - User ID. The default is 1000.
GID - The user's group ID. The default is 1000.
S6_DOWNLOAD_URL - Download URL for s6-overlay. The default is https://github.com/just-containers/s6-overlay/releases/download.
S6_OVERLAY_VERSION - s6-overlay version. By default, the latest version.
S6_ARCH - s6-overlay architecture. The default is x86_64.

How to change Debian distribution release?

The RELEASE build argument allows you to specify the release of the Debian distribution:

$ git clone https://github.com/kyzima-spb/docker-gui.git
$ cd docker-gui/docker
$ docker build -t gui --build-arg RELEASE=bullseye .

How to change s6-overlay version?

$ git clone https://github.com/kyzima-spb/docker-gui.git
$ cd docker-gui/docker
$ docker build -t gui --build-arg S6_OVERLAY_VERSION=3.1.2.0 .

How to change s6-overlay architecture?

We clone the sources of the base image, specify the architecture in the S6_ARCH argument and optionally the version in the S6_OVERLAY_VERSION argument. The available values for the selected version can be found on the downloads page.

Build an image, for example, for Orange Pi:

$ git clone https://github.com/kyzima-spb/docker-gui.git
$ cd docker-gui/docker
$ docker build -t gui --build-arg S6_ARCH=armhf .

How to change UID/GID?

We clone the sources of the base image and build it with the values of the identifiers:

$ git clone https://github.com/kyzima-spb/docker-gui.git
$ cd docker-gui/docker
$ docker build -t gui \
      --build-arg UID=1001 \
      --build-arg GID=1001 \
      .

kyzima-spb / docker-gui