AppImage (all distros) missing RMW provider .so — dlopen'd libs not captured by ldd bundling

[kyrie2to11]

Summary

All three prebuilt AppImages from release 0.9.0 fail to start on a clean machine (no system ROS):

terminate called after throwing an instance of 'rclcpp::exceptions::RCLError'
  what():  failed to initialize rcl init options: failed to load any RMW implementations

Tested with both pj_bridge_ros2-humble-x86_64.AppImage and pj_bridge_ros2-jazzy-x86_64.AppImage (kilted uses the same workflow). Ubuntu 24.04.

Reproduce

chmod +x pj_bridge_ros2-jazzy-x86_64.AppImage
env -i HOME=$HOME PATH=/usr/bin:/bin ./pj_bridge_ros2-jazzy-x86_64.AppImage --ros-args -p port:=9090

Root cause

In .github/workflows/appimage.yaml, conda deps are bundled via ldd:

ldd AppDir/usr/bin/pj_bridge_ros2 | grep "$CONDA_PREFIX" | awk '{print $3}' | xargs -I{} cp ... AppDir/usr/lib/
# then a second pass over AppDir/usr/lib/*.so*

The RMW provider libraries (librmw_fastrtps_cpp.so, librmw_cyclonedds_cpp.so, …) are loaded by dlopen at runtime, so they don't appear in ldd output and are never copied. The image ends up with librmw_implementation.so (linked) and the ament_index markers (copied via share/ament_index), but no provider .so — so rmw_implementation finds the index entry, fails to dlopen the provider, and aborts.

Confirming on the extracted image:

$ find squashfs-root -name 'librmw_*.so'
squashfs-root/usr/lib/librmw_implementation.so        # loader only, no provider
$ find squashfs-root -iname '*fastrtps*.so' -o -iname '*cyclonedds*.so'
(empty)
$ find squashfs-root -path '*rmw_typesupport_cpp*'
squashfs-root/usr/share/ament_index/resource_index/rmw_typesupport_cpp/rmw_fastrtps_cpp
...                                                                 # index markers present, libs absent

Suggested fix

Explicitly copy the RMW provider .so(s) into AppDir/usr/lib/ and pin one in AppRun, e.g.:

cp "$CONDA_PREFIX"/lib/librmw_fastrtps_cpp.so* AppDir/usr/lib/
cp "$CONDA_PREFIX"/lib/librmw_fastrtps_shared_cpp.so* AppDir/usr/lib/ 2>/dev/null || true

and in AppRun:

export RMW_IMPLEMENTATION=rmw_fastrtps_cpp

Workaround (for users)

• The .deb (ros-jazzy-pj-bridge_0.9.0-0noble_amd64.deb) works — it links against system /opt/ros/<distro> and uses the system RMW provider.
• pixi global install pj-bridge-ros2-* also works (conda env ships the provider).