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Docker

Very briefly, Docker is a tool that provides a simple and efficient way to pack everything needed for a specific application in one container. You can also look at it as a lightweight virtual machine running on your computer.

Basic information about Docker and its main concepts can be found here. Of course, you can also take a look at the official website. Don't follow any instructions from these links just yet. They are provided as a general overview and reference you can use in the future. Detailed step-by-step instructions are given below.

Prerequisites

You must have Ubuntu OS installed on your computer. Ideally, this would be Ubuntu 24.04, but another version should work as well.

Step-by-step instructions

Follow these instructions to install the Docker engine.

Then follow these optional steps to manage docker as a non-root user. If you skip this, every docker command will have to be executed with sudo. Skip the "Note: To run Docker without root privileges, see Run the Docker daemon as a non-root user (Rootless mode)." part. This is just a note and we do not need it.

Docker containers are intended to run inside your terminal. In other words, you won't see a desktop like in regular virtual machines. However, graphical applications can still run in the container if you give them permission. To do that, execute

xhost +local:docker

To avoid having to do this every time, we can add that command to our .profile file which executes on every login.

echo "xhost +local:docker > /dev/null" >> ~/.profile

If you have an NVIDIA GPU, please install nvidia-container-toolkit by following these instructions.

Run Crazyflies in the Docker container

Setting up

Clone the this repository:

git clone git@github.com:larics/icuas25_competition.git

Add to ~/.bashrc and source it, or type in the current terminal:

export DOCKER_BUILDKIT=1

Run Dockerfile from the project root directory using the following commands:

# Build a Dockerfile
docker build --ssh default -t crazysim_icuas_img .

# Run the crazysim_img2 container for the fist time
./first_run.sh

# This will create docker container crazysim_icuas_cont and position you into the container

For subsequent use of the container, you can use:

# Start the crazysim_icuas_cont:
docker start -i crazysim_icuas_cont

The following docker commands can also be helpful:

# Start another bash shell in the already running crazysim_icuas_cont container:
docker exec -it crazysim_icuas_cont bash

# Stop the conatainer
docker stop crazysim_icuas_cont

# Delete the container
docker rm crazysim_icuas_cont

If you remove the container, you can always rebuild it from scratch by using first_run.sh script.

The containers crazysim_icuas_cont consists of packages for Crazyflies simulator CrazySim. General information about Crazyflies can be found here.

Note

The ros2 workspace is located in /root/CrazySim/ros2_ws

RUN EMPTY WORLD EXAMPLE

Once inside the container, navigate to /root/CrazySim/ros2_ws/src/icuas25_competition/startup (you can use alias cd_icuas25_competition that will place you in icuas25_competition package). Start the example:

./start.sh

If needed, make startup script executable with chmod +x start.sh. It starts the example with 5 Crazyflies and 5 aruco markers in an empty world. To test that everything is working, in the first pane of the second window you can start teleop_twist, which is already in history. It controls the Crazyflie with id cf_1.

RUN CITY_1 WORLD EXAMPLE

Once inside the container, navigate to /root/CrazySim/ros2_ws/src/icuas25_competition/startup. Edit the _setup.sh script to export ENV_NAME=city_1, then start everything with:

./start.sh

Note

This will not spawn aruco markers. Place them on your own to test!

Interesting topics

  • cf_x/odom - odometry (can be used for feedback)
  • cf_x/image - image from camera (the name of the topic can be changed)
  • cf_x/battery_status - percentage of the battery and general state

How can crazyflies be controlled:

  • cf_x/cmd_attitude - low level controller
  • cf_x/cmd_hover - velocities for horizontal hovering, height can be changed by dynamically changing hovering height
  • cf_x/start_trajectory,cf_x/upload_trajectory - services for executing trajectories
  • cf_x/go_to - service to define point to which cf should go
  • cf_x/cmd_vel - horizontal velocity control, vel_mux.py node subscrbes to it and publishes to cf_x/cmd_hover

If you are working in the group and you are all using the same network, please check ROS_DOMAIN_ID in .bashrc in the container. Random number should be set during the build, however it is possible that some of you got the same number. If that is the situation please change it, so that your simulations do not crash.

Bonus section

The provided Docker image comes with a few preinstalled tools and configs which may simplify your life.

Tmuxinator is a tool that allows you to start a tmux session with a complex layout and automatically run commands by configuring a simple yaml configuration file. Tmux is a terminal multiplexer - it can run multiple terminal windows inside a single window. This approach is simpler than having to do docker exec every time you need a new terminal.

You don't need to write new configuration files for your projects, but some examples will use Tmuxinator. You can move between terminal panes by holding down Ctrl key and navigating with arrow keys. Switching between tabs is done with Shift and arrow keys. If you have a lot of open panes and tabs in your tmux, you can simply kill everything and exit by pressing Ctrl+b and then k.

Here are some links: Tmuxinator, Getting starded with Tmux, Tmux Cheat Sheet

Ranger is a command-line file browser for Linux. While inside the Docker container, you can run the default file browser nautilus with a graphical interface, but it is often easier and quicker to view the files directly in the terminal window. You can start ranger with the command ra. Moving up and down the folders is done with arrow keys and you can exit with a q. When you exit, the working directory in your terminal will be set to the last directory you opened while in Ranger.

Htop is a better version of top - command line interface task manager. Start it with the command htop and exit with q.

VS Code - If you normally use VS Code as your IDE, you can install Dev Containers extension which will allow you to continue using it inside the container. Simply start the container in your terminal (docker start -i crazysim_icuas_cont ) and then attach to it from the VS code (open action tray with Ctrl+Shift+P and select Dev Containers: Attach to Running Container).