“error: command 'x86_64-linux-gnu-gcc' failed with exit status 1” in virtualenv

Most of the time these are dependency-issues.

Following the stack-trace of the gcc compiler one can see the missing files. Sometimes installing the Python development packages is not enough.

For example: I tried to do

pip install requests[security]

in my virtualenv foo. This is the result that the pip-installer gave me.

Failed building wheel for cryptography
Running setup.py bdist_wheel for cffi
Stored in directory: /root/.cache/pip/wheels/99/e7/9a/68b1c8ca6f6f92b5feebd4d9434f50712b84f6a66d1285ea21
Successfully built cffi
Failed to build cryptography
Installing collected packages: cffi, cryptography, pyOpenSSL, ndg-httpsclient, requests
Running setup.py install for cryptography
Complete output from command /opt/foo/django-cms-virtualenv/bin/python -c "import setuptools, tokenize;__file__='/tmp/pip-build-eZaLAG/cryptography/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-BwgYTp-record/install-record.txt --single-version-externally-managed --compile --install-headers /opt/foo/django-cms-virtualenv/include/site/python2.7/cryptography:
running install
running build
running build_py
running egg_info
writing requirements to src/cryptography.egg-info/requires.txt
writing src/cryptography.egg-info/PKG-INFO
writing top-level names to src/cryptography.egg-info/top_level.txt
writing dependency_links to src/cryptography.egg-info/dependency_links.txt
writing entry points to src/cryptography.egg-info/entry_points.txt
warning: manifest_maker: standard file '-c' not found

reading manifest file 'src/cryptography.egg-info/SOURCES.txt'
reading manifest template 'MANIFEST.in'
no previously-included directories found matching 'docs/_build'
warning: no previously-included files matching '*' found under directory 'vectors'
writing manifest file 'src/cryptography.egg-info/SOURCES.txt'
running build_ext
building '_Cryptography_cffi_a269d620xd5c405b7' extension
x86_64-linux-gnu-gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/usr/include/python2.7 -c src/cryptography/hazmat/bindings/__pycache__/_Cryptography_cffi_a269d620xd5c405b7.c -o build/temp.linux-x86_64-2.7/src/cryptography/hazmat/bindings/__pycache__/_Cryptography_cffi_a269d620xd5c405b7.o
src/cryptography/hazmat/bindings/__pycache__/_Cryptography_cffi_a269d620xd5c405b7.c:217:25: fatal error: openssl/aes.h: Datei oder Verzeichnis nicht gefunden
#include <openssl/aes.h>
^
compilation terminated.
error: command 'x86_64-linux-gnu-gcc' failed with exit status 1

The important part is the:

#include <openssl/aes.h>

The compiler makes pretty clear that it is demanding this file - but it is not there in the filesystem.

Knowing that, the only thing left to do is: install the needed libraries!

Find out which package is needed for your distribution: e.g. for Ubuntu you can go to The Ubuntu Package Search Site and enter the missing file you are looking for. In this case "aes.h"

Install the needed packages using your distributions package management tool: e.g. for Ubuntu:

aptitude install libssl-dev

Retry with pip in your virtualenv: