How to overlay the correct way
Let's say I want to overlay the rcl package.
Right now I have eloquent installed from deb packages.
So rcl lib is at /opt/ros/eloquent/lib/librcl.so .
Then I have an overlay workspace overlay_ws, where the rcl repo is checked out from source.
And a development workspace dev_ws.
I build overlway_ws first, then dev_ws.
And I source in this order:
/opt/ros/eloquent/setup.shoverlay_ws/local_setup.shdev_ws/local_setup.sh
The sourcing happens in my .bashrc. So by opening a new terminal or calling an alias I can source the ros environment.
So first I source my environment, then build overlay_ws.
Then source the environment and build dev_ws.
Then source again, to have dev packages available.
But it always gets the installed lib (/opt/ros/..) linked and not the overlayed one.
If I remove the installed lib, it works. But that's not what I want.
Can someone hint me in the right direction?
Is this the way it should work?
Could you clarify when you actually
sourceany workspaces? Right now it's rather ambiguous whether you first build everything and only afterwardssource, or whether you interleave those commands.It would be important to know when you run which command.
Ok, updated my question.
If you start with overlays, I would suggest not to
sourceanything in your.bashrc(at least initially). It will only confuse. Do it manually.The correct order would be:
source /opt/ros/eloquentoverlay_ws(which is actually an underlay I would say)source overlay_wsdev_wssource dev_wsTo
sourcea workspace (or install location) essentially activates it. If you don't do that in the correct order, package paths will not be resolved to the correct workspace.Having written this, I recall there are currently some issues with overlaying and ROS 2 workspaces, but I can't find the details right now.
Perhaps @marguedas can add something here.
If the dev_ws was not build before, the
setup.bashis non existant and I can't source it anyway, which leads me to the next question. Do I need to build dev_ws from a clean state? Is it possible that a previous build cached some cmake linking paths or so? Then sourcing the overlay wouldn' have an effect at all.Now I removed the installed librcl.so as a test, tried to build dev_ws and it failed. So my custom rcl lib is not found although it's built. Then I removed the build folder of the failing package, built again and now it find's my lib. Looks like I need to clean the
dev_wscompletely.@gvdhoorn maybe you're referring to https://answers.ros.org/question/3496... this was a temporary issue that has now been solved.
The suggested workflow of not sourcing automatically before building and building + sourcing moving up the workspace chain looks good :+1: In my experience having dedicated (different) terminals for building and running code helps as wel
However what @madmax is trying to do is not a supported use case that I know of. Building packages already installed from debs in overlay is discouraged. It may work but may break in subtle ways. You'd need to at least make sure to rebuild every dependent of RCL (rclcpp, rclpy and any branch up your dependency tree from rcl) in your overlay and they should be before the debs ones on your various paths (AMENT_PREFIX_PATH, CMAKE_PREFIX_PATH, LD_LIBRARY_PATH, PATH etc) . Otherwise some libraries may still be pointing to the old rcl library ...(more)
Building packages already installed from debs in overlay is discouraged. -> this would be a good hint in the documentation. I do it like that because of the discussion here. And I hoped it would be enough to just build rcl and spdlog package. But after cleaning
dev_wsand building again, it will always take the installed lib instead of the last sourced one.I hoped the sourcing also does something like a library priorization, like on which path to look first for a library when building but that doesn't seem to be the case.
But after opening a new terminal, which resets all the PATH variables, and building
dev_wsfrom there, the linking was correct.Could you pls provide the ROS_PACKAGE_PATH and CMAKE_PREFIX_PATH after all your source operation?