You're reading the documentation for an older, but still supported, version of ROS 2. For information on the latest version, please have a look at Jazzy.

RHEL (source)

System requirements 

The current target Red Hat platforms for Iron Irwini are:

Tier 2: RHEL 9 64-bit

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 C. 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 dnf install langpacks-en glibc-langpack-en
export LANG=en_US.UTF-8

locale  # verify settings

Enable required repositories 

The rosdep database contains packages from the EPEL and PowerTools repositories, which are not enabled by default. They can be enabled by running:

sudo dnf install 'dnf-command(config-manager)' epel-release -y
sudo dnf config-manager --set-enabled crb

Note

This step may be slightly different depending on the distribution you are using. Check the EPEL documentation: https://docs.fedoraproject.org/en-US/epel/#_quickstart

Install development tools 

sudo dnf install -y \
  cmake \
  gcc-c++ \
  git \
  make \
  patch \
  python3-colcon-common-extensions \
  python3-flake8-builtins \
  python3-flake8-comprehensions \
  python3-flake8-docstrings \
  python3-flake8-import-order \
  python3-flake8-quotes \
  python3-mypy \
  python3-pip \
  python3-pydocstyle \
  python3-pytest \
  python3-pytest-repeat \
  python3-pytest-rerunfailures \
  python3-rosdep \
  python3-setuptools \
  python3-vcstool \
  wget

# install some pip packages needed for testing and
# not available as RPMs
python3 -m pip install -U --user \
  flake8-blind-except==0.1.1 \
  flake8-class-newline \
  flake8-deprecated

Build ROS 2 

Get ROS 2 code 

Create a workspace and clone all repos:

mkdir -p ~/ros2_iron/src
cd ~/ros2_iron
vcs import --input https://raw.githubusercontent.com/ros2/ros2/iron/ros2.repos src

Install dependencies using rosdep 

ROS 2 packages are built on frequently updated RHEL systems. It is always recommended that you ensure your system is up to date before installing new packages.

sudo dnf update

sudo rosdep init
rosdep update
rosdep install --from-paths src --ignore-src -y --skip-keys "fastcdr ignition-cmake2 ignition-math6 rti-connext-dds-6.0.1 urdfdom_headers"

Install additional RMW implementations (optional)

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

Build the code in the workspace 

If you have already installed ROS 2 another way (either via RPMs 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_iron/
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 the --packages-skip colcon flag to ignore the package that is causing problems. For instance, if you don’t want to install the large OpenCV library, you could skip building the packages that depend on it using the command:

colcon build --symlink-install --packages-skip image_tools intra_process_demo

Setup environment 

Set up your environment by sourcing the following file.

# Replace ".bash" with your shell if you're not using bash
# Possible values are: setup.bash, setup.sh, setup.zsh
. ~/ros2_iron/install/local_setup.bash

Try some examples 

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

. ~/ros2_iron/install/local_setup.bash
ros2 run demo_nodes_cpp talker

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

. ~/ros2_iron/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 

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

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 dnf 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 Iron install on your system.
If you’re also trying to free up space, you can delete the entire workspace directory with:
```
rm -rf ~/ros2_iron
```

RHEL (source)

System requirements 

System setup 

Set locale 