PIP install unable to find ffi.h even though it recognizes libffi

Question

I have installed libffi on my Linux server as well as correctly set the PKG_CONFIG_PATH environment variable to the correct directory, as pip

Answer 1

You can use CFLAGS (and LDFLAGS or various other compiler and linker options) in front of the pip command (ditto for setup.py):

Something similar to the following should work:

CFLAGS=-I/usr/include/libffi/include pip install pyOpenSSL