Using Python Packages with ROS 2

Goal: Explain how to interoperate with other Python packages from the ROS2 ecosystem.

Note

A cautionary note, if you intended to use pre-packaged binaries (either deb files, or the “fat” binary distributions), the Python interpreter must match what was used to build the original binaries. If you intend to use something like virtualenv or pipenv, make sure to use the system interpreter. If you use something like conda, it is very likely that the interpreter will not match the system interpreter and will be incompatible with ROS2 binaries.

Installing via rosdep

The fastest way to include third-party python packages is to use their corresponding rosdep keys, if available. rosdep keys can be checked via:

These rosdep keys can be added to your package.xml file, which indicates to the build system that your package (and dependent packages) depend on those keys. In a new workspace, you can also quickly install all rosdep keys with:

rosdep install -yr ./path/to/your/workspace

If there aren’t currently rosdep keys for the package that you are interested in, it is possible to add them by following the rosdep key contribution guide.

To learn more about the rosdep tool and how it works, consult the rosdep documentation.

Installing via a package manager

If you don’t want to make a rosdep key, but the package is available in your system package manager (eg apt), you can install and use the package that way:

sudo apt install python3-serial

If the package is available on The Python Package Index (PyPi) and you want to install globally on your system:

python3 -m pip install -U pyserial

If the package is available on PyPi and you want to install locally to your user:

python3 -m pip install -U --user pyserial

Installing via a virtual environment

First, create a Colcon workspace:

mkdir -p ~/colcon_venv/src
cd ~/colcon_venv/

Then setup your virtual environment:

# Make a virtual env and activate it
virtualenv -p python3 ./venv
source ./venv/bin/activate
# Make sure that colcon doesn’t try to build the venv
touch ./venv/COLCON_IGNORE

Next, install the Python packages that you want in your virtual environment:

python3 -m pip install gtsam pyserial… etc

Now you can build your workspace and run your python node that depends on packages installed in your virtual environment.

# Source Foxy and build
source /opt/ros/foxy/setup.bash
colcon build

Note

If you want release your package on Bloom, you should to add the packages you require to rosdep, see the rosdep key contribution guide.