This repository is a collection of files/scripts to conveniently build and run ROS 2 packages inside a Docker container and have shared memory transport between ROS 2 nodes run inside the container and on the host enabled.

When running ROS 2 nodes inside a container and on its host, we might want to transmit messages between them using efficient shared memory transport. However, this requires a non-trivial configuration and the issue has been described multiple times:

• Troubles communicating with ROS2 node in docker container
• ROS2 galactic nodes can't communicate through docker container border
• ROS2-foxy nodes can't communicate through docker container border
• Failed to exchange Messages between two docker containers when run on host network option.(--network=host)
• ROS2 topics on Docker detected by host but can't subscribe
• Running discovery process as root breaks existing processes running as normal user when SHM is used

Transmitting images between Docker container and host using shared memory transport requires

1. running the container with specific options, --network=host --ipc=host --pid=host, and
2. running ROS 2 nodes inside the container by a user with the same ID as the user of the host.

This repository shows the most convenient setup (that I could find so far) to build and run ROS packages inside a Docker container and enable shared memory transport between ROS 2 nodes inside the container and on the host. The setup involves:

• build.sh and run.sh scripts to build/run the container with the correct options
• ros_entrypoint.sh that creates a user inside with matching user/group IDs at startup
• build and run aliases inside the container to build/run colcon workspace as correct user

On host:

./build.sh #Builds and tags Docker image
./run.sh   #Runs Docker image with correct options 

Inside container:

build   #Alias to build colcon_ws as root user
run     #Alias to run ROS package as correct user