The Dockerfile to build the image is within docker/. It contains the build instructions for an image to have ROS Melodic / Ubuntu 18.04 with basic GUI operation if you have hardware that runs Intel Integrated Graphics (No Graphics card setup and Intel CPU).

For those who have a NVIDIA GPU on their setups: please refer to here. I will post some information if there are users who have a NVIDIA GPU in their setup. (Everything relating to ROS will work except for RVIZ and Gazebo which require OpenGL).

Ensure that you have Docker-Compose installed and obviously Docker Desktop for Ubuntu Installed. Link for installation is located here

To observe what the IP address is easily without failure and confusion - once you are SSH'ed into the Duckiebot; you can ping your laptop from the terminal shell from the RaspberryPi. (I.e. run ping <Your-Laptop-Hostname>.local). I have included some regular expressions in my scripts which print out the correct IPs that you will have to edit the docker-compose.yaml file.

Remember to set your ROS_MASTER_URI to the Duckiebots one which is http://raspberrypi.local:11311/. In Docker-Compose this is passed as an argument under the Environment Variable.

environment:
- "ROS_MASTER_URI=http://raspberrypi.local:11311/"

Remember to alter these variables per your setup.

extra_hosts:
  - "<LAPTOP_HOSTNAME>.local:<LAPTOP_IP>"
  - "raspberrypi.local:<PI_IP>"
environment:
  - "ROS_MASTER_URI=http://raspberrypi.local:11311/"
  - "ROS_HOSTNAME=<LAPTOP_HOSTNAME>.local"

There are some notes if you refer to calib/wheel/.

For further references on how I figured out most of this - the tutorial from Open Source Robotics Foundation is here