Why can I use CMake supplied modules (CMakeDependentOption.cmake specifically) locally, but not on CI or Docker?

Question

I have a cmake project that successfully builds locally but errors with

  include could not find load file:

    CmakeDependentOption

when trying to build on a CI platform or in Docker. Note that CMakeDependentOption.cmake is a script that comes with cmake itself. So it should just be available. On CI to install cmake, I wget the relevant cmake release from their downloads page, unzip it and add the bin directory to the PATH environment variable. Then I use the cmake command to build my library. The result is the above error.

I suspect this means that a CMake variable (such as "CMAKE_MODULE_PATH" but not, since this variable seems to be empty at the start of the cmake script) is messed up or not set somehow. The path to the correct file to include is

<cmake_root>/share/cmake-3.18/Modules/CMakeDependentOption.cmake

And I have verified that it exists manually. My question: is there a way to locate this directory from within cmake? Perhaps a cmake --config or cmake --libs mode (a bit like pkg-config?)

Failing that, does anybody have any suggestions as to why this is happening and how to get around it.

Answer 1

You can locally because most likely you don't use a linux based platform, like windows or mac. This is because linux filesystem are case sensitive. Which means CmakeDependentOption is different from CMakeDependentOption .

Docker runs containers in linux, so filenames are gonna be case sensitive, and the include is going to fail if the cases are different.