docker-gui

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

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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.

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• How to create a new image?
  • Create image directory
  • Create service
  • Dockerfile
  • Build
  • Run in daemon mode
• Environment Variables
  • Autostart with a password
  • How to change user or group ID?
• Build Arguments
  • How to change Debian distribution release?
  • How to change s6-overlay version?
  • How to change s6-overlay architecture?

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

backtick -E HOME { homeof user }
s6-env HOME="$HOME"

redirfd -w 2 /dev/null

s6-setuidgid user 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

RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
    --mount=type=cache,target=/var/lib/apt,sharing=locked \
    rm -f /etc/apt/apt.conf.d/docker-clean; \
    echo 'Binary::apt::APT::Keep-Downloaded-Packages "true";' > /etc/apt/apt.conf.d/keep-cache \
    && apt update && apt install -yq --no-install-recommends \
        chromium

COPY ./ /

Build

Build an image file named chromium:

$ docker build -t chromium -f Dockerfile ./root

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, by default 1280x720
• VNC_SERVER_PASSWORD - password for the VNC server, by default not set
• VNC_SERVER_PASSWORD_FILE - password for the VNC server, by default not set
• USER_UID - user ID, by default is 1000
• USER_GID - user's group ID, by default is 1000

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 \
      -e VNC_SERVER_PASSWORD=qwe123 \
      --restart unless-stopped \
      chromium

Example with secrets in Docker Compose:

secrets:
  vnc_password:
    file: ./secrets/vnc_password

services:
  chromium:
    build:
      context: ./root
      dockerfile: ../Dockerfile
    secrets:
      - vnc_password
    ports:
      - "5900:5900"
    environment:
      VNC_SERVER_PASSWORD_FILE: /run/secrets/vnc_password
    restart: unless-stopped

Building the project and running:

$ docker compose --project-directory ./examples/chromium build
$ docker compose --project-directory ./examples/chromium up

How to change user or group ID?

$ docker run -d --name chromium_1 \
      -p 5900:5900 \
      --shm-size 2g \
      -e USER_UID=1001 \
      -e USER_GID=1001 \
      --restart unless-stopped \
      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 bookworm-slim, bookworm, bullseye-slim, bullseye, buster-slim, buster. The default is bookworm-slim.
• 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 \
    -f Dockerfile ./root

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 \
    -f Dockerfile ./root

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 .
    -f Dockerfile ./root