ERC Docker Image

This repository contains an example Dockerfile that can be used to build a docker image that will be run on Leo Rover (ERC edition).
It can be used by the teams as a template for developing their custom software for the ERC competitions.

This example image starts the Freedom agent which connects to your account at Freedom Robotics App, as well as a launch file from an example package which start a ROS node that let's you save images from topics to PNG files.

Building

Login to the Freedom Robotics App, click on Add Device -> Quick Create and copy the URL address from the command (not the whole command).

Now execute the following command as the root user (replace <YOUR_URL> with the address from Freedom Robotics Space Concordia Robotics > LeoRover > Settings > Installation > use the URL not the full command):

docker build -t erc_img --build-arg FREEDOM_URL="<YOUR_URL>" .

Building for Leo Rover

On the competitions, the docker images will be run on the Nvidia Jetson Xavier NX platform which runs on a 64 bit ARM architecture. The images that will be run on the robot also need to be built for this architecture. Otherwise, Jetson will try to emulate to target architecture which will make the software run a lot slower and is prone to errors.

To do this, you can either:

1. Build the image on a Linux machine running 64 bit ARM architecture.
2. Use Docker Buildx to build the image for linux/arm64 platform using QEMU emulation.

To do 1. :

Check if you have the correct architecture by typing:

uname -m

You should see aarch64.
Then, follow the steps from the Building section.

To do 2. :

Here is a great, detailed instruction on building multi-architecture images using the Docker Buildx utility.

In short, here's what you have to do:

You need to have binfmt_misc feature enabled on your system and statically linked QEMU binaries installed. The easiest way to install and register the QEMU binaries is to use a Docker Image based installation:

docker run --rm --privileged multiarch/qemu-user-static --reset -p yes

To gain access to the docker buildx command, you need to enable experimental Docker CLI features:

export DOCKER_CLI_EXPERIMENTAL=enabled

Create a new Buildx Builder (if you did'nt create one before):

docker buildx create --name mybuilder

Set the current builder instance and bootstrap it:

docker buildx use mybuilder
docker buildx inspect --bootstrap

You should see linux/arm64 amoung the available Platforms.
Now, build the image:

docker buildx build --load -t erc_img_arm --platform linux/arm64 --build-arg FREEDOM_URL="<YOUR_URL>" .

Deploying the image

The easiest way to deploy the image is to save it to a tar archive using the docker save command:

docker save erc_img_arm -o erc_img_arm.tar

Lanching

To run the image, simply type:

docker run -it --net=host --name erc_img erc_img

If you want to use it with ROS running on another machine, pass the ROS_IP and ROS_MASTER_URI variables:

docker run -it --net=host -e ROS_IP=<YOUR_IP> -e ROS_MASTER_URI=<MASTER_URI> --name erc_img erc_img

The Freedom agent should start and you should see the device connected on the Freedom Robotics App.

To test the image with the simulated Rover, simply start the simulation on the host machine or on another docker container started with the --net=host option.

Using the example features

The Dockerfile properly configures the image to permit SSH login.
On the Freedom Robotics App, click on Settings -> Remote SSH -> Enable remote SSH. This will open an SSH tunnel that will let you login to your container from the Internet.
To login, paste the resulted command into your terminal. When asked for password, type root.

The start.sh script that is executed by the docker image, configures the environment, so when you login, you can already run ROS commands.
You can start by listing the available topics:

rostopic list

You should see the /image_saver/save topic which is spawned by the image_saver node from the erc_example package.
The node expects Image topic names on that topic and upon receiving a message, saves a single Image from the topic to a PNG file inside the container.
If you have the simulation running, you can try to save an image from the hazcam by executing:

rostopic pub -1 /image_saver/save std_msgs/String "data: '/camera/image_raw'"

An image should be saved inside the /root/.ros directory.

You can also use Freedom Robotics App to send messages on this topic, by going to Settings -> Send command.