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Version: 2.0.0

Workspace build of ROS2 packages

This guide shows how to set up a workspace in ROS2. If you encounter any issues during the process, see the end of this page for Troubleshooting of common issues.

Installation steps​

1. Install the Robot Operating System (Jazzy)​

Follow the ROS2 Installation guide.

2. Install the MRS UAV Core with necessary dependencies​

Follow the ROS2 MRS UAV Core Installation guide.

3. Get aliases that make common ROS2 commands usable​

By default, calling colcon build anywhere creates a workspace there (even in a subdirectory of an workspace). To prevent that, the aliased colcon build crawls back in the directory tree to check if we are in a workspace and if not, will NOT create a workspace automatically. With the aliases, a workspace can be created only by colcon init similarly to catkin_tools in ROS1.

cd ~/git
git clone git@github.com:ctu-mrs/mrs_uav_development.git
cd mrs_uav_development
git checkout ros2

Add to ~/.bashrc (~/.zshrc):

# ROS DEVELOPMENT
# * source this after exporting $ROS_WORKSPACE="<path to your workspace>"
# * workspace is automatically sourced and the soucing is cached
# * to force-source a workspace after adding new packages, call `presource_ros`
source $HOME/git/mrs_uav_development/shell_additions/shell_additions.sh

4. Clone the ROS2 Examples package​

cd ~/git
git clone git@github.com:ctu-mrs/ros2_examples.git

5. Prepare the workspace​

mkdir -p ~/ws_examples/src
ln -s $HOME/git/ros2_examples $HOME/ws_examples/src/

Now we need to set the workspace compilation flags using mixin.

First, install mixin

sudo apt install python3-colcon-mixin

then add MRS mixin.

colcon mixin add default https://raw.githubusercontent.com/ctu-mrs/colcon-mixin-repository/master/index.yaml
colcon mixin update default

Add the following config to ~/ws_examples/colcon_defaults.yaml to set the number of build threads to 8 and build with the "rel-with-deb-info" mixin profile:

build:
  parallel-workers: 8
  mixin:
    - rel-with-deb-info

For more information regarding setting workspace flags using mixins see ROS2 Workspace Profiles

6. Build the workspace​

cd ~/ws_examples/
colcon init
colcon build

Add to ~/.bashrc (~/.zshrc) before sourcing of source $HOME/git/mrs_uav_development/shell_additions/shell_additions.sh:

## workspace to be sourced
export ROS_WORKSPACE="$HOME/ws_examples"

Do not put any manual sourcing of the workspace or /opt/ros/jazzy/ into your ~/.bashrc (~/.zshrc)! Sourcing mrs_uav_development sources the ROS_WORKSPACE specified in ~/.bashrc (~/.zshrc) automatically (or it sources /opt/ros/jazzy if no ROS_WORKSPACE is specified.

7. Colorful output for colcon commands​

If you're accustomed to the colorful output of catkin_tools from ROS 1, you can achieve a similar look and feel with colcon in ROS 2. This makes it easier to read build logs and quickly identify important messages or errors.

To get started, install the colcon-ansi-colors-example extension using pip:

pip install git+https://github.com/cottsay/colcon-ansi-colors-example --break-system-packages

Note: The --break-system-packages flag is often required to install pip packages globally on systems where the package manager is strict about system files.

Once the extension is installed, you can use the new output style with the following command:

colcon --output-style catkin_tools build

If you like the colorful output and want to use it by default for all colcon commands, add the following line to your shell's configuration file (e.g., ~/.bashrc for Bash or ~/.zshrc for Zsh):

export COLCON_DEFAULT_OUTPUT_STYLE=catkin_tools

After adding the line, be sure to open a new terminal or run source ~/.bashrc (or the appropriate file) for the change to take effect.

Troubleshooting

Optimization flags​

  • Issue: Estimation manager is outputting errors with time since last msg too long
  • Reason: Workspace is built without optimization flags.
  • Solution: See step 5. and make sure the workspace is built with rel_with_deb_info

Tmux config​

  • Issue: After running the tmux session, the terminal looks weird and tmux bindings don't work
  • Reason: tmux config is missing in /etc/ctu-mrs/tmux.conf
  • Solution: sudo apt install mrs-uav-shell-additions

MRS UAV testing not building​

  • Issue: The package mrs_uav_testing is not building
  • Reason: It hasn't been converted to ROS2 yet.
  • Solution: touch ~/ws_mrs_uav_core/src/mrs_uav_core/ros_packages/mrs_uav_testing/COLCON_IGNORE

Colcon build not working as expected​

  • Issue: Calling colcon build does not create a workspace and start building it.
  • Reason: We have an alias for colcon, to make its usage less awkward. See step 3 for details.
  • Solution: First call colcon init in the root of the workspace, then colcon build.

Colcon build fails to find ament_package​

  • Issue: Calling colcon build fails with error: ModuleNotFoundError: No module named 'ament_package'
  • Reason: ROS_WORKSPACE is sourced before building the workspace.
  • Solution: Remove ROS_WORKSPACE from ~/.bashrc (~/.zshrc), open new terminal, build the workspace, return ROS_WORKSPACE to ~/.bashrc (~/.zshrc).

Any ros2 command fails​

  • Issue: Calling any ros2 commands fails with importlib.metadata.PackageNotFoundError: No package metadata was found for ros2cli
  • Reason: /tmp/ros_presource_output.sh exists and needs to be deleted.
  • Solution: Remove rm /tmp/ros_presource_output.sh