[glfw] CMake "Could NOT find OpenGL"

[helmesjo]

From my understanding, the conan-glfw package should be enough to get required OpenGL headers and libraries (eg. the libgl1-mesa-dev package, which I can see is installed). However CMake still fails to find OpenGL.
I've added glfw/3.2.1 as a build requirement. Am I missing something very obvious, or is there something wrong with the package?

Package and Environment Details (include every applicable attribute)

• Package Name/Version: glfw/3.2.1
• Operating System+version: Linux Ubuntu 16.04
• Compiler+version: gcc-5
• Docker image: conanio/gcc5
• Conan version: conan 1.11.0
• Python version: Python 3.7.0

Logs (Include/Attach if Applicable)

CMake Error at /usr/share/cmake-3.12/Modules/FindPackageHandleStandardArgs.cmake:137 (message):
  Could NOT find OpenGL (missing: OPENGL_opengl_LIBRARY OPENGL_glx_LIBRARY)

[helmesjo]

I opted for building natively instead (no cross compiling from x64 to x86), since there where too many issues revolving around OpenGL and cross compiling.
See example here.