Failed to install psycopg2 on mac os

Question

I am using python3.7.2 and pip 19.2.2 for a python application. The problem is that I can't install the dependency psycopg2 2.8.3 on MacOS.

Below is the error I got on running pip install psycopg2:

ld: library not found for -lssl
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  error: command 'clang' failed with exit status 1
  ----------------------------------------
  ERROR: Failed building wheel for psycopg2

It seems that ssl is not installed so I tried to install pip install sssl but got this error:

ERROR: Command errored out with exit status 1:
     command: /Users/joey/.pyenv/versions/3.7.2/bin/python3.7 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/9c/fcm6pxnj39b1t777zpcfpbdh0000gn/T/pip-install-2ldzdiz0/ssl/setup.py'"'"'; __file__='"'"'/private/var/folders/9c/fcm6pxnj39b1t777zpcfpbdh0000gn/T/pip-install-2ldzdiz0/ssl/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base pip-egg-info
         cwd: /private/var/folders/9c/fcm6pxnj39b1t777zpcfpbdh0000gn/T/pip-install-2ldzdiz0/ssl/
    Complete output (6 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/private/var/folders/9c/fcm6pxnj39b1t777zpcfpbdh0000gn/T/pip-install-2ldzdiz0/ssl/setup.py", line 33
        print 'looking for', f
                          ^
    SyntaxError: Missing parentheses in call to 'print'. Did you mean print('looking for', f)?
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

I don't understand why it failed. Is this because of a wrong version or relates to MacOS?

I have tried the method mentioned in this post: How to install psycopg2 with "pip" on Python?. I installed postgressql on the Mac and added /usr/local/Cellar/postgresql/11.5/bin/ on PATH env. But it doesn't help.

Answer 1

I think this thread may be of help error installing psycopg2, library not found for -lssl

clang is the default c compiler on osx, and is required for some python libraries to be built correctly. The ssl error is actually the clang linker complaining that there is no ssl library available to be used. The above thread should resolve your issue.

Answer 2

I had the same issue, and looked at the thread posted by Nate, but found my solution here: How to update Xcode from command line, posted by Roy Huang, who referenced https://forums.developer.apple.com/thread/104296

It turns out Mojave and/or Xcode 10 does not create a /usr/include directory, which psycopg2 needs to be able to install.