How to find dependencies on shared objects in ROS2?

edit

I'm trying to build ROS2 nodes using Bazel, similar to what https://github.com/nicolov/ros-bazel has done for ROS1. The core idea there is to use a binary installation (already present in /opt/ros/galactic or fat archive downloaded by Bazel automatically) and crawl that to extract information necessary to create Bazel targets for individual packages.

My basic approach is this:

• Go over each directory in share.
• Check its cmake/ament_cmake_export_dependencies-extras.cmake and cmake/ament_cmake_export_libraries-extras.cmake for _exported_dependencies and _exported_libraries, respectively. This way I can find the .so this target exports and other targets it depends on.

This seems to mostly work. However, some dependencies I don't know how to trace. For example, how do I pull in libspdlog.so.1? It looks like this belongs to the package spdlog_vendor, but I don't see that expressed in CMake files or package.xml. Another example is rmw_cyclonedds_cpp. This needs a couple of iceoryx*.so files, but they don't seem to be mentioned anywhere.

For now I work around this by manually providing the missing information, but I would really like to automate the process as much as possible. One thing I considered was running ldd on the libraries and extracting the required info from its output. I'm pretty sure this would work, but I wonder if there's a better way. Any hints? Thanks!