Installing psycopg2 fails on MacOS with unclear error message

Question

Trying to install psycopg2 using pip 19.1 on MacOS 10.14.4 returns the lengthy error message below. I understand there are warnings related to gcc, but given the actual error me

Answer 1

Thanks for adding the error log, without which it would have been very hard to find the issue. Nice work.

This part of the log was really interesting:

    gcc -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -arch x86_64 -g -DPSYCOPG_VERSION=2.8.2 (dt dec pq3 ext lo64) -DPG_VERSION_NUM=110002 -DHAVE_LO64=1 -I/Library/Frameworks/Python.framework/Versions/3.7/include/python3.7m -I. -I/usr/local/Cellar/postgresql/11.2_1/include -I/usr/local/Cellar/postgresql/11.2_1/include/server -c psycopg/typecast.c -o build/temp.macosx-10.9-x86_64-3.7/psycopg/typecast.o
    gcc -bundle -undefined dynamic_lookup -arch x86_64 -g build/temp.macosx-10.9-x86_64-3.7/psycopg/psycopgmodule.o build/temp.macosx-10.9-x86_64-3.7/psycopg/green.o build/temp.macosx-10.9-x86_64-3.7/psycopg/pqpath.o build/temp.macosx-10.9-x86_64-3.7/psycopg/utils.o build/temp.macosx-10.9-x86_64-3.7/psycopg/bytes_format.o build/temp.macosx-10.9-x86_64-3.7/psycopg/libpq_support.o build/temp.macosx-10.9-x86_64-3.7/psycopg/win32_support.o build/temp.macosx-10.9-x86_64-3.7/psycopg/solaris_support.o build/temp.macosx-10.9-x86_64-3.7/psycopg/connection_int.o build/temp.macosx-10.9-x86_64-3.7/psycopg/connection_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/cursor_int.o build/temp.macosx-10.9-x86_64-3.7/psycopg/cursor_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/column_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/replication_connection_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/replication_cursor_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/replication_message_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/diagnostics_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/error_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/conninfo_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/lobject_int.o build/temp.macosx-10.9-x86_64-3.7/psycopg/lobject_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/notify_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/xid_type.o build/temp.macosx-10.9-x86_64-3.7/psycopg/adapter_asis.o build/temp.macosx-10.9-x86_64-3.7/psycopg/adapter_binary.o build/temp.macosx-10.9-x86_64-3.7/psycopg/adapter_datetime.o build/temp.macosx-10.9-x86_64-3.7/psycopg/adapter_list.o build/temp.macosx-10.9-x86_64-3.7/psycopg/adapter_pboolean.o build/temp.macosx-10.9-x86_64-3.7/psycopg/adapter_pdecimal.o build/temp.macosx-10.9-x86_64-3.7/psycopg/adapter_pint.o build/temp.macosx-10.9-x86_64-3.7/psycopg/adapter_pfloat.o build/temp.macosx-10.9-x86_64-3.7/psycopg/adapter_qstring.o build/temp.macosx-10.9-x86_64-3.7/psycopg/microprotocols.o build/temp.macosx-10.9-x86_64-3.7/psycopg/microprotocols_proto.o build/temp.macosx-10.9-x86_64-3.7/psycopg/typecast.o -L/usr/local/lib -lpq -lssl -lcrypto -o build/lib.macosx-10.9-x86_64-3.7/psycopg2/_psycopg.cpython-37m-darwin.so
    ld: library not found for -lssl

The 2nd gcc had a mention of this:

-L/usr/local/lib -lpq -lssl -lcrypto -o ...

That means, compilation process was looking for a library (-l) that happens to be ssl. See gcc manual (https://linux.die.net/man/1/gcc). It says that -l is to search the library named library (in our case ssl) when linking.

Something with ssl library was missing.

Google search lead to a reported issue: https://github.com/psycopg/psycopg2/issues/492. Joe Kemp's answer (https://github.com/psycopg/psycopg2/issues/492#issuecomment-278481164) suggests setting an environment variable like so:

export LDFLAGS="-L/usr/local/opt/openssl/lib"

Other options were listed here: Can't install psycopg2 with pip in virtualenv on Mac OS X 10.7.

It appears that your setting LDFLAGS solved the issue.