Building ROS 2 on Ubuntu Linux

Table of Contents

System requirements 

The current Debian-based target platforms for Galactic Geochelone are:

Tier 1: Ubuntu Linux - Focal Fossa (20.04) 64-bit
Tier 3: Debian Linux - Bullseye (11) 64-bit

Other Linux platforms with varying support levels include:

Arch Linux, see alternate instructions
Fedora Linux, see alternate instructions
OpenEmbedded / webOS OSE, see alternate instructions

As defined in REP 2000.

Make sure you have a locale which supports UTF-8. If you are in a minimal environment (such as a docker container), the locale may be something minimal like POSIX. We test with the following settings. However, it should be fine if you’re using a different UTF-8 supported locale.

locale  # check for UTF-8

sudo apt update && sudo apt install locales
sudo locale-gen en_US en_US.UTF-8
sudo update-locale LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8
export LANG=en_US.UTF-8

locale  # verify settings

Add the ROS 2 apt repository 

You will need to add the ROS 2 apt repository to your system. First, make sure that the Ubuntu Universe repository is enabled by checking the output of this command.

apt-cache policy | grep universe
 500 http://us.archive.ubuntu.com/ubuntu focal/universe amd64 Packages
     release v=20.04,o=Ubuntu,a=focal,n=focal,l=Ubuntu,c=universe,b=amd64

If you don’t see an output line like the one above, then enable the Universe repository with these instructions.

sudo apt install software-properties-common
sudo add-apt-repository universe

Now add the ROS 2 apt repository to your system. First authorize our GPG key with apt.

sudo apt update && sudo apt install curl gnupg lsb-release
sudo curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.key  -o /usr/share/keyrings/ros-archive-keyring.gpg

Then add the repository to your sources list.

echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/ros-archive-keyring.gpg] http://packages.ros.org/ros2/ubuntu $(source /etc/os-release && echo $UBUNTU_CODENAME) main" | sudo tee /etc/apt/sources.list.d/ros2.list > /dev/null

Install development tools and ROS tools 

sudo apt update && sudo apt install -y \
  build-essential \
  cmake \
  git \
  python3-colcon-common-extensions \
  python3-flake8 \
  python3-pip \
  python3-pytest-cov \
  python3-rosdep \
  python3-setuptools \
  python3-vcstool \
  wget
# install some pip packages needed for testing
python3 -m pip install -U \
  flake8-blind-except \
  flake8-builtins \
  flake8-class-newline \
  flake8-comprehensions \
  flake8-deprecated \
  flake8-docstrings \
  flake8-import-order \
  flake8-quotes \
  pytest-repeat \
  pytest-rerunfailures \
  pytest \
  setuptools

Ubuntu 18.04 is not an officially supported platform, but may still work. You’ll need at least the following additional dependencies:

python3 -m pip install -U importlib-metadata importlib-resources

Get ROS 2 code 

Create a workspace and clone all repos:

mkdir -p ~/ros2_galactic/src
cd ~/ros2_galactic
wget https://raw.githubusercontent.com/ros2/ros2/galactic/ros2.repos
vcs import src < ros2.repos

Install dependencies using rosdep 

sudo rosdep init
rosdep update
rosdep install --from-paths src --ignore-src -y --skip-keys "fastcdr rti-connext-dds-5.3.1 urdfdom_headers"

Note: If you’re using a distribution that is based on Ubuntu (like Linux Mint) but does not identify itself as such, you’ll get an error message like Unsupported OS [mint]. In this case append --os=ubuntu:focal to the above command.

Install additional DDS implementations (optional)

If you would like to use another DDS or RTPS vendor besides the default, Eclipse Cyclone DDS, you can find instructions here.

Build the code in the workspace 

If you have already installed ROS 2 another way (either via Debians or the binary distribution), make sure that you run the below commands in a fresh environment that does not have those other installations sourced. Also ensure that you do not have source /opt/ros/${ROS_DISTRO}/setup.bash in your .bashrc. You can make sure that ROS 2 is not sourced with the command printenv | grep -i ROS. The output should be empty.

More info on working with a ROS workspace can be found in this tutorial.

cd ~/ros2_galactic/
colcon build --symlink-install

Note: if you are having trouble compiling all examples and this is preventing you from completing a successful build, you can use COLCON_IGNORE in the same manner as CATKIN_IGNORE to ignore the subtree or remove the folder from the workspace. Take for instance: you would like to avoid installing the large OpenCV library. Well then simply run touch COLCON_IGNORE in the cam2image demo directory to leave it out of the build process.

Environment setup 

Source the setup script 

Set up your environment by sourcing the following file.

. ~/ros2_galactic/install/local_setup.bash

Try some examples 

In one terminal, source the setup file and then run a C++ talker:

. ~/ros2_galactic/install/local_setup.bash
ros2 run demo_nodes_cpp talker

In another terminal source the setup file and then run a Python listener:

. ~/ros2_galactic/install/local_setup.bash
ros2 run demo_nodes_py listener

You should see the talker saying that it’s Publishing messages and the listener saying I heard those messages. This verifies both the C++ and Python APIs are working properly. Hooray!

Next steps after installing 

Continue with the tutorials and demos to configure your environment, create your own workspace and packages, and learn ROS 2 core concepts.

Using the ROS 1 bridge 

The ROS 1 bridge can connect topics from ROS 1 to ROS 2 and vice-versa. See the dedicated documentation on how to build and use the ROS 1 bridge.

Additional RMW implementations (optional)

The default middleware that ROS 2 uses is Cyclone DDS, but the middleware (RMW) can be replaced at runtime. See the guide on how to work with multiple RMWs.

Alternate compilers 

Using a different compiler besides gcc to compile ROS 2 is easy. If you set the environment variables CC and CXX to executables for a working C and C++ compiler, respectively, and retrigger CMake configuration (by using --force-cmake-config or by deleting the packages you want to be affected), CMake will reconfigure and use the different compiler.

Clang 

To configure CMake to detect and use Clang:

sudo apt install clang
export CC=clang
export CXX=clang++
colcon build --cmake-force-configure

If you installed your workspace with colcon as instructed above, “uninstalling” could be just a matter of opening a new terminal and not sourcing the workspace’s setup file. This way, your environment will behave as though there is no Galactic install on your system.
If you’re also trying to free up space, you can delete the entire workspace directory with:
```
rm -rf ~/ros2_galactic
```