X11Proxy

X11Proxy is a lightweight X11 proxy designed for containerized environments. It provides an AF_UNIX socket for Docker containers to connect to the host's X11 display, enabling GUI applications to run inside containers with minimal setup.

Features

• Proxies X11 connections from a UNIX socket (default: :5) to the host's current $DISPLAY.
• Simple, minimal codebase.
• Ideal for Docker and other container runtimes.
• No complex configuration required.

Use Case

Run GUI applications inside Docker containers by exposing a UNIX socket for X11 forwarding.

Quick Start

1. Start X11Proxy

x11proxy

By default, this will listen on /tmp/.X11-unix/X5 and forward to your current $DISPLAY.

2. Run a Docker Container

Mount the proxy socket into your container and set DISPLAY accordingly:

docker run -it \
    -e DISPLAY=:5 \
    -v /tmp/.X11-unix/X5:/tmp/.X11-unix/X5 \
    x11-app-image

Replace x11-app-image with your GUI application's image.

3. Example: Running xeyes

docker run -it \
    -e DISPLAY=:5 \
    -v /tmp/.X11-unix/X5:/tmp/.X11-unix/X5 \
    x11docker/xeyes

Alternatively, you can use a custom script such as hello_xclock.sh to run xclock inside a Docker container:

./hello_xclock.sh

This script should mount the proxy socket and set the DISPLAY variable appropriately, demonstrating how to launch GUI applications with minimal setup.

Security

• The proxy socket is protected by file permissions (0700), ensuring only your user can access it.

• For remote X sessions, valid xauth credentials are required. X11Proxy injects these credentials into the connection automatically, so your Docker container does not need to have your xauth file.

• Note: X11Proxy does not provide isolation between GUI applications. Once connected, containerized apps can interact with other X11 clients on the same display (e.g. capturing input, reading window contents). This is a known limitation of X11 itself and may be addressed in future versions with optional sandboxing or per-client filtering.

License

BSD 2-Clause License. See https://opensource.org/license/bsd-2-clause for details.

Credits

Inspired by X11Docker, but with a minimal approach.