Trouble installing m2crypto with pip on OS X / macOS

pip install m2crypto

Generates the following output:

building 'M2Crypto.__m2crypto' extension
swigging SWIG/_m2crypto.i to SWIG/_m2crypto_wrap.c
swig -python -I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -I/usr/include -I/usr/include/openssl -includeall -modern -o SWIG/_m2crypto_wrap.c SWIG/_m2crypto.i
SWIG/_m2crypto.i:30: Error: Unable to find 'openssl/opensslv.h'
SWIG/_m2crypto.i:33: Error: Unable to find 'openssl/safestack.h'
SWIG/_evp.i:12: Error: Unable to find 'openssl/opensslconf.h'
SWIG/_ec.i:7: Error: Unable to find 'openssl/opensslconf.h'
error: command 'swig' failed with exit status 1

I've run:

brew install swig

I wanted a nicer way without installing manually and using only Homebrew (which also does not link openssl by default). Also using pip was a requirement. This seems to work with newest m2crypto 0.22.5. I also tested it once with m2crypto 0.22.3 and seems also to work. The OpenSSL version here is 1.0.2d:

brew install openssl
brew install swig

Finally install m2crypto on macOS in your Bash. It is a long command but it changes SWIG and clang environment variables only during pip install so that m2crypto will get all OpenSSL requirements:

env LDFLAGS="-L$(brew --prefix openssl)/lib" \
CFLAGS="-I$(brew --prefix openssl)/include" \
SWIG_FEATURES="-cpperraswarn -includeall -I$(brew --prefix openssl)/include" \
pip install m2crypto

btw. the last command also works if you use e.g. a requirements.txt.

Update:
Additional also the command for fish shell users...

env LDFLAGS="-L"(brew --prefix openssl)"/lib" \
CFLAGS="-I"(brew --prefix openssl)"/include" \
SWIG_FEATURES="-cpperraswarn -includeall -I"(brew --prefix openssl)"/include" \
pip install m2crypto

thanks to therealmarv env flags i was able to get this to work with the macports version of openssl/swig, this is what i did:

sudo port install openssl
sudo port install swig
sudo port install swig-python

then use therealmarv lines but replace "$(brew --prefix openssl)" with the dir from macports which should be "/opt/local"

sudo env LDFLAGS="-L/opt/local/lib" \
CFLAGS="-I/opt/local/include" \
SWIG_FEATURES="-cpperraswarn -includeall -I/opt/local/include" \
pip install M2Crypto

I just went through a lot of pain getting this working in El Capitan. Here is what I had to do:

Install OpenSSL (you have to use an older version, m2crypto will not compile otherwise)

curl -O https://www.openssl.org/source/openssl-0.9.8zg.tar.gz
tar -xvzf openssl-0.9.8zg.tar.gz
cd openssl-0.9.8zg
./Configure --prefix=/usr/local darwin64-x86_64-cc
make && make test
sudo make install

Install m2crypto

git clone https://github.com/martinpaljak/M2Crypto.git    
cd M2Crypto
python setup.py build build_ext --openssl=/usr/local
sudo python setup.py install build_ext --openssl=/usr/local

AFAIK it is installed... I still have to do some testing though.

Got exact same issue on Ubuntu 18.04 LTS, while trying to execute

pip install M2Crypto==0.24.0

Did the following to get rid of it:

sudo apt-get install swig
sudo apt-get install libssl1.0-dev

This fixed my problem (Python 2.7):

export PYTHONPATH=$PYTHONPATH:/usr/local/lib/python2.7/site-packages

macos v10.15.6
m2crypto v0.35.6
pip v20

Solution by therealmarv works, If the program does not take effect, you can try to upgrade your brew packages. Before the solution.

brew update              # update homebrew self
brew upgrade             # upgrade all 

sudo apt-get install python-m2crypto