ros2_docker_examples

This repo shows few different ways to deal with ROS 2 node interconnectivity depending whether you:

• use nodes on a single machine or on multiple machines
• use nodes with or without docker
• connect ROS 2 nodes over LAN or WAN

To focus purely on connectivity, not on running fancy ROS 2 software or robots in Gazebo, I will go through different scenarios based on a simple ROS 2 system containing of 3 nodes:

• /turtlesim - a very simple, simulator for learning ROS where you simulate … a turtle :)
• /move_controller - node for controlling the movement of the turtle
• /color_controller - node that is changing the color of the line drawn by a turtle each second

The solution is scalable, so what you will learn can be applied in very complex distributed ROS 2 systems as well!

Below, there are 4 example use cases using the same code base, launched in different architecture scenarios.

Before you start …

Make sure you have Docker and Docker-Compose installed on your laptop.

The official instruction is the best tutorial but here’s a quick rundown for you (for Linux):

sudo -E apt-get -y install apt-transport-https ca-certificates software-properties-common && \
curl -sL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add - && \
arch=$(dpkg --print-architecture) && \
sudo -E add-apt-repository "deb [arch=${arch}] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" && \
sudo -E apt-get update && \
sudo -E apt-get -y install docker-ce docker-compose

sudo systemctl daemon-reload
sudo systemctl restart docker

ROS 2 Foxy installed on your laptop is needed only for [Eg. 0] section.

[Eg. 0] Running without Docker

cd ros2_ws
colcon build

source /opt/ros/foxy/setup.bash
source install/setup.bash # full path might be: ~/ros2_docker_examples/ros2_ws/install/setup.bash

ros2 launch my_turtle_bringup turtlesim_demo.launch.py

[Eg. 1] Running in a single container

Please stay in ros2_docker_examples/ directory while executing those commands:

sudo chmod +x eg1/ros_entrypoint.sh

docker build -t turtle_demo -f eg1/Dockerfile .

xhost local:root

sudo docker run --rm -it \
--env DISPLAY \
--volume /tmp/.X11-unix:/tmp/.X11-unix:rw \
turtle_demo \
ros2 launch my_turtle_bringup turtlesim_demo.launch.py

[Eg. 2] Running in two containers (using docker-compose)

cd eg2
docker-compose up --build

[Eg. 3] PROBLEM: Running on two computers in different networks

Because two ROS 2 devices are in different networks, DDS can not perform auto-discovery.

Also devices can not reach each other because they do not have neither public nor static IP addresses and are behind Wi-Fi router NAT.

[Eg. 3] SOLUTION: Connecting ROS 2 machines using VPN

Ready to use example is available in eg3/ folder. There are two separate subfolders with a docker-compose.yml file which should be launched on two separate devices from different networks.

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