How to include external library (.so) into ROS2 environment

asked 2021-06-21 08:45:16 -0500

bojankoce gravatar image

updated 2021-06-21 08:47:44 -0500

Hello there!

My development environment consists of ROS2 foxy and Ubuntu 18.04. I have ROS2 package (my_ros2_pkg) with ROS2 node (my_ros2_node). Inside the ROS2 node, I want to use an external C library (not some external ROS2 package).

I used the following approach to bring the library code from the Git as well as to properly install the library. Here is the excerpt of CMakeLists.txt file of my_ros2_pkg:

include(ExternalProject)

    ExternalProject_Add(my_ext_library
        GIT_REPOSITORY    https://github.com/my_ext_library.git
        GIT_TAG           master
        SOURCE_DIR        ${CMAKE_BINARY_DIR}/my_lib/src
        BINARY_DIR        ${CMAKE_BINARY_DIR}/my_lib/build
        CONFIGURE_COMMAND cmake ${CMAKE_BINARY_DIR}/my_lib/src
        BUILD_COMMAND     make
        INSTALL_COMMAND   make install DESTDIR=${CMAKE_BINARY_DIR}/my_lib/install
    )
    include_directories("${CMAKE_BINARY_DIR}/my_lib/install/usr/local/include")
    link_directories("${CMAKE_BINARY_DIR}/my_lib/install/usr/local/lib")

As a consequence, the source code of the external library is properly downloaded, the library is properly built and installed. .so files of the library can be found under ros2_workspace/build/my_ros2_pkg/my_lib/install/usr/local/lib

However, when I try to run my_ros2_node with

ros2 run my_ros2_pkg my_ros2_node

I have the following ROS2 error:

/home/ros2_workspace/install/my_ros2_pkg/lib/my_ros2_pkg/my_ros2_node: error while loading shared libraries: my_lib.so.1: cannot open shared object file: No such file or directory

It seems that ROS2 looks for the shared object (.so) library files under ros2_workspace/install/my_ros2_pkg/lib/my_ros2_pkg folder and not under ros2_workspace/build/my_ros2_pkg/my_lib/install/usr/local/lib where they actually reside.

How can I fix this issue and properly include the path to the .so files into the ROS2 environment? My CMakeLists.txt file of my_ros2_pkg also contains this line:

add_dependencies(my_ros2_node my_ext_library)

but to no avail. Do you have any idea what I am missing here? Thank you very much for your time and efforts.

Sincerely, Bojan.

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Comments

1

I'm no cmake expert, But I've done my fair share of making some _vendor type ros2 packages.. (1 is too many for me..)

You could try something like:

INSTALL_COMMAND make install ${CMAKE_CURRENT_BINARY_DIR}/../install/lib/my_ros2_pkg

Or if that doesn't work try adding an additional && cp ...... stuff to your INSTALL_COMMAND..

Good luck!

ChuiV gravatar image ChuiV  ( 2021-06-21 09:44:10 -0500 )edit

Hey, @ChuiV! Thanks for your answer. It seems that the .so files are expected in /usr/lib location. When I moved the file there I was able to load the shared library. I will try what you suggest because I would like to download source code, build and install the library and use such installed .so files from my ROS2 package.

Cheers, Bojan.

bojankoce gravatar image bojankoce  ( 2021-06-21 09:47:43 -0500 )edit

In times past, I've made a dedicated *_vendor package (such as the sqlite3_vendor package. I didn't write that particular one, but I've used it as a template to make my own.) that wraps around the external project cmake.

Then in regular ros2 packages, you can add dependencies on your "vendor" package, which should automatically add those libraries into the link path.

This whole process is quite a pain. I do with there was an easier way... But once it's done, it works pretty good.

ChuiV gravatar image ChuiV  ( 2021-06-21 10:06:49 -0500 )edit
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