How to use SDK for ROS2 packages?

[apbr]

Are there instructions anywhere on how to use the Yocto SDK to build a ROS2 package and install it on the target device so it can be run with ros2 run <package> <executable>?

I tried building the ROS2 examples (https://github.com/ros2/examples) using the Yocto SDK.

I added TOOLCHAIN_HOST_TASK:append = "${ROS_SDK_HOST_PACKAGES}" and TOOLCHAIN_TARGET_TASK:append = "${ROS_SDK_TARGET_PACKAGES} example-interfaces" to my image recipe, built the sdk and installed it on my system.

Following #1204 (comment), I continued with the following steps:
Source the sdk environment
Set environment variables:

export ROS_VERSION=2
export ROS_PYTHON_VERSION=3
export ROS_AUTOMATIC_DISCOVERY_RANGE=SUBNET
export ROS_DISTRO=jazzy
export PYTHONPATH=$OECORE_NATIVE_SYSROOT/usr/lib/python3.12/site-packages:$OECORE_TARGET_SYSROOT/opt/ros/jazzy/lib/python3.12/site-packages
export AMENT_PREFIX_PATH=$OECORE_TARGET_SYSROOT/opt/ros/jazzy

Build it:

colcon build --merge-install --install-base $PWD/install/arm64 --cmake-args \
" -DCMAKE_TOOLCHAIN_FILE=$CMAKE_TOOLCHAIN_FILE" \
" -DCMAKE_STAGING_PREFIX=$PWD/install/arm64" \
" -DBUILD_TESTING=OFF"

I then copied install/arm64 onto my target device.
Followed by source /opt/ros/jazzy/setup.bash and source ./local_setup.bash

After that ROS still doesn't know about the packages I built. (They are not part of ros2 pkg list and e.g. ros2 run examples_rclcpp_minimal_publisher publisher_member_function also doesn't work.)
What does work is manually run one of the binaries in ./lib/.

Any idea what I'm missing?

[rcwoolley]

I can't recall if we tried running with ros2 when building with colcon with the SDK. It is a workflow we should support. I suspect that either AMENT_PREFIX_PATH isn't set properly or the packaging files didn't get copied into the right place.

What does AMENT_PREFIX_PATH get set to after you source local_setup.bash?

Where do you copy the contents of install/arm64 to on the device? (eg. /opt/ros/jazzy/share/examples_rclcpp_minimal_publisher ?)

[apbr]

I copied install/arm64 to an arbitrary location on disk.
I just tried it again (source /opt/ros/jazzy/setup.bash followed by source ./local_setup.bash) on a different device and now it just works.
AMENT_PREFIX_PATH is /data/my-tests/arm64:/opt/ros/jazzy (I copied install/arm64 to /data/my-tests/). That looks good to me as well.
No idea, what changed. So it seems the process works in general, but there is an issue on my side with the other device.
Thanks for your support and sorry for bothering ;)

[robwoolley]

Glad to hear that it works for you. No bother at all. I am sure this discussion will help others that want to do this too.