Error 'openssl/crypto.h' file not found when installing PycURL on Mac using pip

When installing Python3 packages on macOS X 10.15 Catalina using pip install -r requirements.txt I am getting this error:

× Running setup.py install for pycurl did not run successfully.
  │ exit code: 1
  ╰─> [25 lines of output]
      /private/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/pip-install-8r44qz4e/pycurl_09ab3d56141443439eb3f41fa62f7b0f/setup.py:771: DeprecationWarning: distutils Version classes are deprecated. Use packaging.version instead.
        if LooseVersion(distutils.__version__) > LooseVersion("1.0.1"):
      /private/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/pip-install-8r44qz4e/pycurl_09ab3d56141443439eb3f41fa62f7b0f/setup.py:773: DeprecationWarning: distutils Version classes are deprecated. Use packaging.version instead.
        if LooseVersion(distutils.__version__) < LooseVersion("1.0.3"):
      Using curl-config (libcurl 7.84.0)
      running install
      /usr/local/lib/python3.9/site-packages/setuptools/command/install.py:34: SetuptoolsDeprecationWarning: setup.py install is deprecated. Use build and pip and other standards-based tools.
        warnings.warn(
      running build
      running build_py
      creating build
      creating build/lib.macosx-10.15-x86_64-cpython-39
      creating build/lib.macosx-10.15-x86_64-cpython-39/curl
      copying python/curl/__init__.py -> build/lib.macosx-10.15-x86_64-cpython-39/curl
      running build_ext
      building 'pycurl' extension
      creating build/temp.macosx-10.15-x86_64-cpython-39
      creating build/temp.macosx-10.15-x86_64-cpython-39/src
      clang -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -DPYCURL_VERSION=\"7.43.0\" -DHAVE_CURL_OPENSSL=1 -DHAVE_CURL_SSL=1 -I/usr/local/Cellar/curl/7.84.0/include -I/usr/local/opt/[email protected]/Frameworks/Python.framework/Versions/3.9/include/python3.9 -c src/docstrings.c -o build/temp.macosx-10.15-x86_64-cpython-39/src/docstrings.o
      In file included from src/docstrings.c:4:
      src/pycurl.h:170:13: fatal error: 'openssl/crypto.h' file not found
      #   include <openssl/crypto.h>
                  ^~~~~~~~~~~~~~~~~~
      1 error generated.
      error: command '/usr/bin/clang' failed with exit code 1
      [end of output]

So It fails on installing PycURL because it cannot find the openssl include directory.

I have first added cryptography==37.0.4 to the requirements.txt file but then I got:

src/pycurl.h:178:13: fatal error: 'openssl/ssl.h' file not found

Then I have tried installing latest openssl with:

brew update
brew install openssl
brew link --force openssl
ln -s /usr/local/opt/openssl/lib/libcrypto.3.dylib /usr/local/lib/
ln -s /usr/local/opt/openssl/lib/libssl.3.dylib /usr/local/lib/
ln -s /usr/local/Cellar/openssl/3.0.4/bin/openssl /usr/local/bin/openssl

But it didn't help.

I also tried:

export PYCURL_SSL_LIBRARY=openssl
export LDFLAGS="-L/usr/local/opt/openssl@3/lib"
export CPPFLAGS="-I/usr/local/opt/openssl@3/include"

pip install --no-cache-dir --compile --ignore-installed --install-option="--with-openssl" pycurl

But also with no success. Any help on this?

Solution

What eventually helped was:

Remove pycurl from the requirements.txt file
Install openssl with: brew install openssl
Find openssl installation directory with

$ brew --prefix openssl
/usr/local/opt/openssl@3

$ ls -la /usr/local/opt/openssl@3
lrwxr-xr-x  1 runner  admin  25 Jul  6 09:13 /usr/local/opt/openssl@3 -> ../Cellar/openssl@3/3.0.4

Install PycURL specifying inline the above openssl install directories like this:

PYCURL_SSL_LIBRARY=openssl LDFLAGS="-L/usr/local/Cellar/openssl@3/3.0.4/lib" CPPFLAGS="-I/usr/local/Cellar/openssl@3/3.0.4/include" pip3 install --no-cache-dir pycurl

Now the PycURL installs without any problem:

Collecting pycurl
  Downloading pycurl-7.45.1.tar.gz (233 kB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 233.9/233.9 kB 64.5 MB/s eta 0:00:00
  Preparing metadata (setup.py): started
  Preparing metadata (setup.py): finished with status 'done'
Building wheels for collected packages: pycurl
  Building wheel for pycurl (setup.py): started
  Building wheel for pycurl (setup.py): finished with status 'done'
  Created wheel for pycurl: filename=pycurl-7.45.1-cp39-cp39-macosx_10_15_x86_64.whl size=146607 sha256=aff9581cbd6ddec739c529df376ad2d4edf49dafdad179a9b68bddeb60a739b3
  Stored in directory: /private/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/pip-ephem-wheel-cache-hjqadgim/wheels/4d/ef/77/ffab9dc4b0016ce4f780b752e0020815e416f0d27a701a816f
Successfully built pycurl
Installing collected packages: pycurl
Successfully installed pycurl-7.45.1