How to pass sysroot from Yocto to cmake - cmake

Question

I am using a Yocto recipe to build a cmake project. In the Yocto enviroment, I confirmed that --sysroot=my-app/recipe-sysroot and all dependent libraries have been installed into that location. In my CMakeList.txt, I set link_directories(/usr/lib), but error messages occur while building to indicate the dependent libraries cannot be found.
Does anyone know how to pass the Yocto sysroot environment to cmake?
My recipe,
inherit cmake
DEPENDS = "\
azure-iot-sdk-c \
openssl \
zlib \
curl \
boost \
parson \
gtest \
"
S = "${WORKDIR}/git"
B = "${WORKDIR}/build"
EXTRA_OECMAKE = "\
-DCMAKE_BUILD_TYPE=Debug \
-DBUILD_SAMPLES=ON \
-DBUILD_TESTS=ON \
-DBUILD_TOOLS=ON \
"
FILES_${PN}-staticdev = "${libdir}/*.a"
FILES_${PN} += "${libdir}/*.so"
FILES_SOLIBSDEV = ""
INSANE_SKIP_${PN} += "dev-so rpaths"
And if I set the real path in my CMakeList, it works,
set(LIBRARY_DIR "${CMAKE_CURRENT_LIST_DIR}/../recipe-sysroot/usr/lib")
set(STATIC_LIBRARY ${LIBRARY_DIR}/libiothub_client.a)
But if I set the related path according to sysroot, it does not work,
set(LIBRARY_DIR "/usr/lib")

Answer 1

Don't do:
set(LIBRARY_DIR "${CMAKE_CURRENT_LIST_DIR}/../recipe-sysroot/usr/lib")
It is usually not necessary to have any yocto specific information in your cmake. Instead add
include(GNUInstallDirs)
In your recipe add:
inherit cmake
If your cmake installs the static library and headers correctly e.g.:
install (TARGETS <yourtarget> DESTINATION ${CMAKE_INSTALL_LIBDIR})
file(GLOB HEADERS include/*.h)
install(FILES ${HEADERS} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
My above advice should work, if you not install the static library using cmake you have to define an do_install task in your package recipe. For example
do_install() {
install -m 0755 -d ${D}${libdir}
install -m 0755 ${B}/test-staticlibrary.a ${D}/${libdir}
}
If you post your cmake files I can assist you further