More detail for pip install failure

Requirement already up-to-date: pip in /usr/lib/python2.7/site-packages
Collecting ansible==2.3.1.0 (from -r /requirements.txt (line 1))
  Downloading ansible-2.3.1.0.tar.gz (4.3MB)
Collecting awscli==1.11.36 (from -r /requirements.txt (line 2))
  Downloading awscli-1.11.36-py2.py3-none-any.whl (1.1MB)
Collecting boto==2.45.0 (from -r /requirements.txt (line 3))
  Downloading boto-2.45.0-py2.py3-none-any.whl (1.3MB)
Collecting boto3==1.4.4 (from -r /requirements.txt (line 4))
  Downloading boto3-1.4.4-py2.py3-none-any.whl (127kB)
Collecting botocore==1.4.93 (from -r /requirements.txt (line 5))
  Downloading botocore-1.4.93-py2.py3-none-any.whl (3.1MB)
Collecting cffi==1.4.2 (from -r /requirements.txt (line 6))
  Downloading cffi-1.4.2.tar.gz (365kB)
Requirement already satisfied: colorama==0.3.7 in /usr/lib/python2.7/site-packages (from -r /requirements.txt (line 7))
Collecting cryptography==1.3.1 (from -r /requirements.txt (line 8))
  Downloading cryptography-1.3.1.tar.gz (383kB)
Requirement already satisfied: docutils==0.13.1 in /usr/lib/python2.7/site-packages (from -r /requirements.txt (line 9))
Collecting ecdsa==0.13 (from -r /requirements.txt (line 10))
  Downloading ecdsa-0.13-py2.py3-none-any.whl (86kB)
Collecting futures==3.0.5 (from -r /requirements.txt (line 11))
  Downloading futures-3.0.5-py2-none-any.whl
Collecting jsonref==0.1 (from -r /requirements.txt (line 12))
  Downloading jsonref-0.1.tar.gz
Collecting jsonschema==2.5.1 (from -r /requirements.txt (line 13))
  Downloading jsonschema-2.5.1-py2.py3-none-any.whl
Collecting Jinja2==2.8 (from -r /requirements.txt (line 14))
  Downloading Jinja2-2.8-py2.py3-none-any.whl (263kB)
Collecting jmespath==0.9.0 (from -r /requirements.txt (line 15))
  Downloading jmespath-0.9.0-py2.py3-none-any.whl
Collecting kubernetes==1.0.0 (from -r /requirements.txt (line 16))
  Downloading kubernetes-1.0.0-py2.py3-none-any.whl (577kB)
Requirement already satisfied: MarkupSafe==0.23 in /usr/lib/python2.7/site-packages (from -r /requirements.txt (line 17))
Collecting netaddr==0.7.18 (from -r /requirements.txt (line 18))
  Downloading netaddr-0.7.18-py2.py3-none-any.whl (1.5MB)
Collecting paramiko==1.16.0 (from -r /requirements.txt (line 19))
  Downloading paramiko-1.16.0-py2.py3-none-any.whl (169kB)
Collecting pyasn1==0.1.9 (from -r /requirements.txt (line 20))
  Downloading pyasn1-0.1.9-py2.py3-none-any.whl
Collecting pycparser==2.10 (from -r /requirements.txt (line 21))
  Downloading pycparser-2.10.tar.gz (206kB)
Collecting pycrypto==2.6.1 (from -r /requirements.txt (line 22))
  Downloading pycrypto-2.6.1.tar.gz (446kB)
Requirement already satisfied: python-dateutil==2.6.0 in /usr/lib/python2.7/site-packages (from -r /requirements.txt (line 23))
Collecting PyYAML==3.11 (from -r /requirements.txt (line 24))
  Downloading PyYAML-3.11.zip (371kB)
Requirement already satisfied: rsa==3.4.2 in /usr/lib/python2.7/site-packages (from -r /requirements.txt (line 25))
Collecting semver==2.7.7 (from -r /requirements.txt (line 26))
  Downloading semver-2.7.7.tar.gz
Requirement already satisfied: s3transfer==0.1.10 in /usr/lib/python2.7/site-packages (from -r /requirements.txt (line 27))
Requirement already satisfied: six==1.10.0 in /usr/lib/python2.7/site-packages (from -r /requirements.txt (line 28))
Requirement already satisfied: setuptools in /usr/lib/python2.7/site-packages (from ansible==2.3.1.0->-r /requirements.txt (line 1))
Requirement already satisfied: idna>=2.0 in /usr/lib/python2.7/site-packages (from cryptography==1.3.1->-r /requirements.txt (line 8))
Requirement already satisfied: enum34 in /usr/lib/python2.7/site-packages (from cryptography==1.3.1->-r /requirements.txt (line 8))
Requirement already satisfied: ipaddress in /usr/lib/python2.7/site-packages (from cryptography==1.3.1->-r /requirements.txt (line 8))
Collecting functools32; python_version == "2.7" (from jsonschema==2.5.1->-r /requirements.txt (line 13))
  Downloading functools32-3.2.3-2.zip
Collecting certifi (from kubernetes==1.0.0->-r /requirements.txt (line 16))
  Downloading certifi-2017.4.17-py2.py3-none-any.whl (375kB)
Collecting urllib3 (from kubernetes==1.0.0->-r /requirements.txt (line 16))
  Downloading urllib3-1.21.1-py2.py3-none-any.whl (131kB)
Collecting websocket-client (from kubernetes==1.0.0->-r /requirements.txt (line 16))
  Downloading websocket_client-0.40.0.tar.gz (196kB)
Collecting oauth2client (from kubernetes==1.0.0->-r /requirements.txt (line 16))
  Downloading oauth2client-4.1.1-py2.py3-none-any.whl (185kB)
Collecting backports.ssl_match_hostname (from websocket-client->kubernetes==1.0.0->-r /requirements.txt (line 16))
  Downloading backports.ssl_match_hostname-3.5.0.1.tar.gz
Collecting pyasn1-modules>=0.0.5 (from oauth2client->kubernetes==1.0.0->-r /requirements.txt (line 16))
  Downloading pyasn1_modules-0.0.9-py2.py3-none-any.whl (60kB)
Collecting httplib2>=0.9.1 (from oauth2client->kubernetes==1.0.0->-r /requirements.txt (line 16))
  Downloading httplib2-0.10.3.tar.gz (204kB)
Installing collected packages: Jinja2, PyYAML, ecdsa, pycrypto, paramiko, ansible, jmespath, botocore, awscli, boto, boto3, pycparser, cffi, pyasn1, cryptography, futures, jsonref, functools32, jsonschema, certifi, urllib3, backports.ssl-match-hostname, websocket-client, pyasn1-modules, httplib2, oauth2client, kubernetes, netaddr, semver
  Found existing installation: Jinja2 2.9.6
    Uninstalling Jinja2-2.9.6:
      Successfully uninstalled Jinja2-2.9.6
  Found existing installation: PyYAML 3.12
    DEPRECATION: Uninstalling a distutils installed project (PyYAML) has been deprecated and will be removed in a future version. This is due to the fact that uninstalling a distutils project will only partially uninstall the project.
    Uninstalling PyYAML-3.12:
      Successfully uninstalled PyYAML-3.12
  Running setup.py install for PyYAML: started
    Running setup.py install for PyYAML: finished with status 'done'
  Running setup.py install for pycrypto: started
    Running setup.py install for pycrypto: finished with status 'done'
  Found existing installation: paramiko 2.1.2
    Uninstalling paramiko-2.1.2:
      Successfully uninstalled paramiko-2.1.2
  Found existing installation: ansible 2.2.0.0
    Uninstalling ansible-2.2.0.0:
      Successfully uninstalled ansible-2.2.0.0
  Running setup.py install for ansible: started
    Running setup.py install for ansible: finished with status 'done'
  Found existing installation: jmespath 0.9.3
    Uninstalling jmespath-0.9.3:
      Successfully uninstalled jmespath-0.9.3
  Found existing installation: botocore 1.5.69
    Uninstalling botocore-1.5.69:
      Successfully uninstalled botocore-1.5.69
  Found existing installation: awscli 1.11.106
    Uninstalling awscli-1.11.106:
      Successfully uninstalled awscli-1.11.106
  Found existing installation: pycparser 2.17
    Uninstalling pycparser-2.17:
      Successfully uninstalled pycparser-2.17
  Running setup.py install for pycparser: started
    Running setup.py install for pycparser: finished with status 'done'
  Found existing installation: cffi 1.10.0
    Uninstalling cffi-1.10.0:
      Successfully uninstalled cffi-1.10.0
  Running setup.py install for cffi: started
    Running setup.py install for cffi: finished with status 'error'
    Complete output from command /usr/bin/python2 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-HnNdYY/cffi/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-VebhbI-record/install-record.txt --single-version-externally-managed --compile:
    Package libffi was not found in the pkg-config search path.
    Perhaps you should add the directory containing `libffi.pc'
    to the PKG_CONFIG_PATH environment variable
    Package 'libffi', required by 'virtual:world', not found
    Package libffi was not found in the pkg-config search path.
    Perhaps you should add the directory containing `libffi.pc'
    to the PKG_CONFIG_PATH environment variable
    Package 'libffi', required by 'virtual:world', not found
    Package libffi was not found in the pkg-config search path.
    Perhaps you should add the directory containing `libffi.pc'
    to the PKG_CONFIG_PATH environment variable
    Package 'libffi', required by 'virtual:world', not found
    Package libffi was not found in the pkg-config search path.
    Perhaps you should add the directory containing `libffi.pc'
    to the PKG_CONFIG_PATH environment variable
    Package 'libffi', required by 'virtual:world', not found
    Package libffi was not found in the pkg-config search path.
    Perhaps you should add the directory containing `libffi.pc'
    to the PKG_CONFIG_PATH environment variable
    Package 'libffi', required by 'virtual:world', not found
    running install
    running build
    running build_py
    creating build
    creating build/lib.linux-x86_64-2.7
    creating build/lib.linux-x86_64-2.7/cffi
    copying cffi/setuptools_ext.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/vengine_gen.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/commontypes.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/backend_ctypes.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/cparser.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/cffi_opcode.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/verifier.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/lock.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/vengine_cpy.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/__init__.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/gc_weakref.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/recompiler.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/api.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/ffiplatform.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/model.py -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/_cffi_include.h -> build/lib.linux-x86_64-2.7/cffi
    copying cffi/parse_c_type.h -> build/lib.linux-x86_64-2.7/cffi
    running build_ext
    building '_cffi_backend' extension
    creating build/temp.linux-x86_64-2.7
    creating build/temp.linux-x86_64-2.7/c
    gcc -fno-strict-aliasing -Os -fomit-frame-pointer -g -DNDEBUG -Os -fomit-frame-pointer -g -fPIC -DUSE__THREAD -I/usr/include/ffi -I/usr/include/libffi -I/usr/include/python2.7 -c c/_cffi_backend.c -o build/temp.linux-x86_64-2.7/c/_cffi_backend.o
    c/_cffi_backend.c:13:17: fatal error: ffi.h: No such file or directory
     #include <ffi.h>
                     ^
    compilation terminated.
    error: command 'gcc' failed with exit status 1
    
    ----------------------------------------
  Rolling back uninstall of cffi
Command "/usr/bin/python2 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-HnNdYY/cffi/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-VebhbI-record/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /tmp/pip-build-HnNdYY/cffi/