Docker Environment

The entire simulation environment runs inside a Docker container managed by VS Code Dev Containers. This ensures everyone on the team has an identical setup regardless of their host OS.

Base image

FROM ros:humble-ros-base

This gives us Ubuntu Jammy 22.04 with ROS 2 Humble pre-installed.

What’s installed

Simulation stack

Package	Purpose
Gazebo Ignition Fortress	Physics simulation engine
`ros-humble-ros-gz-sim`	ROS 2 / Gazebo integration
`ros-humble-ros-ign-bridge`	Message bridging between ROS and Gazebo
`ros-humble-ros2-controllers`	Joint state broadcaster + trajectory controller
`ros-humble-gz-ros2-control`	Hardware interface for Gazebo
`ros-humble-rviz2`	Robot visualization
`ros-humble-xacro`	URDF macro processing
`ros-humble-joint-state-publisher-gui`	Joint state publishing GUI

Display stack (headless GUI)

Package	Purpose
`xserver-xorg-core` + `xserver-xorg-video-dummy`	Virtual X server with no real GPU
`openbox`	Lightweight window manager
`x11vnc`	VNC server for remote X11 access
`novnc` + `websockify`	Browser-based VNC client
`mesa-utils`, `libgl1-mesa-*`	Software OpenGL rendering

Python packages

Package	Purpose
`onshape-to-robot`	CAD-to-URDF conversion (used by genbot)
`open3d`	STL mesh decimation
`ruff`	Python linter
`moteus`	Motor controller interface (for hardware integration)
`opencv-python`	Computer vision

Build tools

Package	Purpose
`python3-colcon-common-extensions`	ROS 2 workspace build system
`python3-rosdep`	ROS dependency installer
`git`	Version control

Container user

The container runs as a non-root user trickfire with passwordless sudo. This matches standard development practices and avoids permission issues.

RUN useradd trickfire --shell /bin/bash --create-home
RUN echo "trickfire ALL=(ALL) NOPASSWD: ALL" > /etc/sudoers.d/user

Dev Container configuration

The devcontainer.json configures how VS Code opens the container:

Workspace mount: The repo is bind-mounted into the container at /home/trickfire/gazebo-simulations.

Port forwarding: Ports 6080 (noVNC) and 5900 (VNC) are forwarded to the host.

Privileged mode: The container runs with --privileged and device access for hardware interaction (USB, CAN bus).

Post-create command: scripts/clean_build.sh runs automatically to clear stale build artifacts.

VS Code extensions: Pre-installs Python, C++, ROS, URDF, Docker, and formatting extensions.

Headless display system

Since Docker containers have no monitor, we use a virtual X11 server so Gazebo and RViz can render.

Architecture

Xorg (dummy driver)  →  x11vnc  →  websockify  →  Browser
      ↑                                              ↑
  Openbox WM                                    noVNC client
      ↑                                         (port 6080)
  Gazebo / RViz

xorg.conf explained

The custom X11 config at /etc/X11/xorg.conf defines a fake display:

Section	Purpose
`Module`	Loads GLX extension for OpenGL support inside X11
`Device`	Creates a virtual GPU using the `dummy` driver with 256 MB of virtual VRAM
`Monitor`	Defines a fake monitor with plausible refresh rates
`Screen`	Sets the resolution and 24-bit color depth
`ServerLayout`	Ties everything together into one virtual display

Environment variables

Variable	Value	Set in
`DISPLAY`	`:1`	Dockerfile / launch.env
`VNC_PORT`	`5900`	Dockerfile
`NOVNC_PORT`	`6080`	Dockerfile

Why this approach?

Alternatives like Xvfb don’t support GLX properly, which means Gazebo’s 3D rendering fails. Using Xorg with a dummy driver + Mesa software rendering gives us full OpenGL support without needing a real GPU. The VNC + noVNC layer makes it accessible from any browser.

Extending the container

To add system packages, edit .devcontainer/Dockerfile and rebuild the container. For Python packages, add them to the pip3 install section.

After changing the Dockerfile, use Dev Containers: Rebuild Container in VS Code’s Command Palette.