When building with OpenSSL on macOS you may run into some non-obvious issues.

Copied from our C Driver Development guide:

Use OpenSSL on macOS:

brew install openssl
cmake -DENABLE_SSL=OPENSSL -DOPENSSL_ROOT_DIR=/usr/local/opt/openssl/lib -DOPENSSL_INCLUDE_DIR=/usr/local/opt/openssl/include .
make

You may need to rm -rf CMakeCache.txt CMakeFiles/ in order to clear the default Darwin SSL CMake configuration from a previous build

Looking at our CMakeLists.txt file it looks like ENABLE_SSL=OPENSSL is the only necessary define. It might be worth printing out a message if the OS is macOS and ENABLE_SSL=OPENSSL is defined without OPENSSL_ROOT_DIR or OPENSSL_INCLUDE_DIR.

In my case, CMake was including OpenSSL from one directory I was trying to build against in
but it was trying to link it from another. The solution was to define OPENSSL_ROOT_DIR to the OpenSSL directory I wanted to link to.