Installing mod_wsgi for Python 3.7 virtualenv - django

Question

Trying to install mod_wsgi for Python 3.7 to complete setup of Django. But it fails with following error message
Collecting mod-wsgi
Using cached https://files.pythonhosted.org/packages/9e/37/dd336068ece37c43957aa337f25c59a9a6afa98086e5507908a2d21ab807/mod_wsgi-4.6.4.tar.gz
Building wheels for collected packages: mod-wsgi
Running setup.py bdist_wheel for mod-wsgi ... error
Complete output from command /home/user/myproject_env/bin/python3.7 -u -c "import setuptools, tokenize;__file__='/tmp/pip-install-9hnl4thc/mod-wsgi/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" bdist_wheel -d /tmp/pip-wheel-a9t55ene --python-tag cp37:
WARNING: The Python installation you are using does not appear to have
been installed with a shared library, or in the case of MacOS X, as a
framework. Where these are not present, the compilation of mod_wsgi may
fail, or if it does succeed, will result in extra memory being used by
all processes at run time as a result of the static library needing to
be loaded in its entirety to every process. It is highly recommended
that you reinstall the Python installation being used from source code,
supplying the '--enable-shared' option to the 'configure' script when
configuring the source code prior to building and installing it.
...
running build_ext
building 'mod_wsgi.server.mod_wsgi-py37' extension
creating build/temp.linux-x86_64-3.7
creating build/temp.linux-x86_64-3.7/src
creating build/temp.linux-x86_64-3.7/src/server
...
gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -fPIC -I/usr/include/httpd -I/home/user/python/include/python3.7m -c src/server/wsgi_stream.c -o build/temp.linux-x86_64-3.7/src/server/wsgi_stream.o -I/usr/include/httpd -I. -I/usr/include/apr-1 -DLINUX -D_REENTRANT -D_GNU_SOURCE -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -pthread -I/usr/include/apr-1 -I/usr/include/apr-1
gcc -pthread -shared build/temp.linux-x86_64-3.7/src/server/wsgi_thread.o build/temp.linux-x86_64-3.7/src/server/mod_wsgi.o build/temp.linux-x86_64-3.7/src/server/wsgi_buckets.o build/temp.linux-x86_64-3.7/src/server/wsgi_memory.o build/temp.linux-x86_64-3.7/src/server/wsgi_interp.o build/temp.linux-x86_64-3.7/src/server/wsgi_restrict.o build/temp.linux-x86_64-3.7/src/server/wsgi_logger.o build/temp.linux-x86_64-3.7/src/server/wsgi_server.o build/temp.linux-x86_64-3.7/src/server/wsgi_convert.o build/temp.linux-x86_64-3.7/src/server/wsgi_metrics.o build/temp.linux-x86_64-3.7/src/server/wsgi_validate.o build/temp.linux-x86_64-3.7/src/server/wsgi_daemon.o build/temp.linux-x86_64-3.7/src/server/wsgi_apache.o build/temp.linux-x86_64-3.7/src/server/wsgi_stream.o -o build/lib.linux-x86_64-3.7/mod_wsgi/server/mod_wsgi-py37.cpython-37m-x86_64-linux-gnu.so -L/home/user/python/lib -L/home/user/python/lib/python3.7/config-3.7m-linux -lpython3.7m
/usr/bin/ld: /home/user/python/lib/libpython3.7m.a(abstract.o): relocation R_X86_64_32S against symbol `_Py_NotImplementedStruct' can not be used when making a shared object; recompile with -fPIC
...
/usr/bin/ld: /home/user/python/lib/libpython3.7m.a(getopt.o): relocation R_X86_64_32S against `.rodata.str4.4' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: /home/user/python/lib/libpython3.7m.a(parser.o): relocation R_X86_64_32 against `.rodata.str1.8' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Nonrepresentable section on output
collect2: error: ld returned 1 exit status
error: command 'gcc' failed with exit status 1
----------------------------------------
Command "/home/user/myproject_env/bin/python3.7 -u -c "import setuptools, tokenize;__file__='/tmp/pip-install-9hnl4thc/mod-wsgi/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-record-fxo44dv3/install-record.txt --single-version-externally-managed --compile --install-headers /home/user/myproject_env/include/site/python3.7/mod-wsgi" failed with error code 1 in /tmp/pip-install-9hnl4thc/mod-wsgi/
Here is the version information:
Apache 2.4.6
CentOS 7
Python 3.7.0
Django 2.0.5
Edit:
gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-28)
httpd-devel-2.4.6-80.el7.centos.1.x86_64

Answer 1

As is documented in mod_wsgi documentation, your issue is lack of shared library for Python.
http://modwsgi.readthedocs.io/en/develop/user-guides/installation-issues.html#lack-of-python-shared-library
http://modwsgi.readthedocs.io/en/develop/user-guides/installation-issues.html#mixing-32-bit-and-64-bit-packages
If installing Python from source code yourself, also read:
http://blog.dscpl.com.au/2015/06/installing-custom-python-version-into.html
Ignore that talks about docker. Same issues arise. You have to be careful about selecting configure options.

Answer 2

As the warning from installation indicates, you're attempting to install mod-wsgi into a python which does not provide a shared object.
When compiling python from source, add the --enable-shared flag so that it produces a libpython#.#.so shared object which can be linked against

Answer 3

Thanks #Graham Dumpleton for sharing the useful links.
I have installed python from source packages with only --enable-shared, so got error "python: error while loading shared libraries: libpython3.6m.so.1.0: cannot open shared object file: No such file or directory" when tried to install packages via pip3
so did the below steps to make it work.
./configure --prefix /usr/local --enable-shared LDFLAGS="-Wl,-rpath,/usr/local/lib"
make
make install
now pip3 install mod-wsgi worked fine.