ros_gz_bridge can't compile on humble/garden: rosidl_pycommon on Ubuntu 22.04, Win10 WSL2

[Twenkid]

Hi, I'm trying to use ros_gz bridge, but I'm facing two problems.

The bridge from the ros2 installation works, but only when a simulation is called with: "ign gazebo" as in the examples here, for sensors_demo.

If the same demo is invoked with gz sim, the topic appears in gz topic -l and ros2 topic list, but there's no image in rqt_view_image.

I tried to build it from source and tried to follow all instructions and tips I could find, cloning the humble branch etc., setting GZ_VERSION=garden etc., but so far it always ends up there:

ModuleNotFoundError: No module named 'rosidl_pycommon'

Traceback (most recent call last):
  File "/home/tosh/ros_gz_ws/src/ros_gz/ros_gz_bridge/bin/ros_gz_bridge_generate_tests", line 25, in <module>
    from ros_gz_bridge import generate_test_cpp
  File "/home/tosh/ros_gz_ws/src/ros_gz/ros_gz_bridge/ros_gz_bridge/__init__.py", line 21, in <module>
    from rosidl_pycommon import expand_template
ModuleNotFoundError: No module named 'rosidl_pycommon'
Traceback (most recent call last):
  File "/home/tosh/ros_gz_ws/src/ros_gz/ros_gz_bridge/bin/ros_gz_bridge_generate_tests", line 25, in <module>
    from ros_gz_bridge import generate_test_cpp
  File "/home/tosh/ros_gz_ws/src/ros_gz/ros_gz_bridge/ros_gz_bridge/__init__.py", line 21, in <module>
    from rosidl_pycommon import expand_template
ModuleNotFoundError: No module named 'rosidl_pycommon'
Traceback (most recent call last):
  File "/home/tosh/ros_gz_ws/src/ros_gz/ros_gz_bridge/bin/ros_gz_bridge_generate_tests", line 25, in <module>
    from ros_gz_bridge import generate_test_cpp
  File "/home/tosh/ros_gz_ws/src/ros_gz/ros_gz_bridge/ros_gz_bridge/__init__.py", line 21, in <module>
    from rosidl_pycommon import expand_template
ModuleNotFoundError: No module named 'rosidl_pycommon'
gmake[2]: *** [CMakeFiles/test_ros_publisher.dir/build.make:80: generated/test/gz_publisher.cpp] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:421: CMakeFiles/test_ros_publisher.dir/all] Error 2
gmake[2]: *** [CMakeFiles/test_gz_subscriber.dir/build.make:80: generated/test/gz_publisher.cpp] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:448: CMakeFiles/test_gz_subscriber.dir/all] Error 2
gmake[2]: *** [CMakeFiles/test_gz_publisher.dir/build.make:80: generated/test/gz_publisher.cpp] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:394: CMakeFiles/test_gz_publisher.dir/all] Error 2
gmake: *** [Makefile:146: all] Error 2
---
Failed   <<< ros_gz_bridge [1.27s, exited with code 2]

Summary: 2 packages finished [5.00s]
  1 package failed: ros_gz_bridge
  1 package had stderr output: ros_gz_bridge
  3 packages not processed

Also ROS documentation suggests that this module is not supported for humble:
https://index.ros.org/p/rosidl_pycommon/#humble

The rosidl ... pkgs are installed in ROS, I can't find "rosidl_pycommon" in particular, some py binding or something

https://github.com/ros2/rosidl

Here:
https://repo.ros2.org/status_page/humble_rhel.html

I see only "ros-rolling-rosidl-pycommon | 3.4.0-1"

Is humble and gz sim actually supported anymore and what's a possible workaround or switching to Rolling is the solution?

(One I saw is capturing the gz messages I want from another program and posting them myself to ROS, or just the ROS node capturing them using gazebo code or something, but I don't know yet how much work would that involve.)

Thanks.

Environment

• OS Version: 22.04 WSL
• Source, cloned from here, branch humble. The current now. Possibly: 9b0e3a9

Description

• Expected behavior: A complete build.
• Actual behavior: Fails due to a missing dependency.

Steps to reproduce

The instructions from this repo.

Output

See above.

[Twenkid]

I tried a partial workaround:

ros2 run ros_gz_image image_bridge /rgbd_camera/image /rgbd_camera/image

The topics appear in rqt_view

• However without images with gz sim:

gz sim -v --render-engine ogre sensors_demo.sdf

...

• WIth ign gazebo the images show up:

ign gazebo -v --render-engine ogre sensors_demo.sdf

[Twenkid]

Maybe I figured it out - I checked again, I discovered that git branch displayed ros2, IDK why. Re-cloned properly and this time it did complete (it takes a lot of RAM/page file though).

Then it didn't work until I read the bridge command from the example carefully - I noticed that the declared type was for Ignition, that's why it works only with ign...

It should be gz.msgs.Image, not ignition.msg.Image.

ros2 run ros_gz_bridge parameter_bridge /rgbd_camera/depth_image@sensor_msgs/msg/[email protected]

Please update the examples. Thanks

[mjcarroll]

(it takes a lot of RAM/page file though)

Yes, there are a lot of things happening at compile time with templates. The binaries are suggested if you are on a limited platform.

It should be gz.msgs.Image, not ignition.msg.Image.

Depending on the branch, it should be compatible with both. Which branch did you end up using?

[Twenkid]

Right, binary is easier, but there wasn't such a combination listed for my case: humble + garden. (I finally compiled with the humble branch, rosidl error happened to has been with the ros2 branch which I thought was humble). As of RAM I had plenty (32 GB), but I use to fill it with stuff and RAM disks. I mentioned that for anyone else who encounters WSL crashes while building, it could be out of memory error and nothing with the source or compatibility, but sometimes it is not clear, because the WSL consoles just suddenly return to Windows.

[azeey]

I don't think there's any remaining issue here, so I'll go ahead and close it