Failed building wheel for cffi
I am trying to install silkaj on Raspberry Pi 3B+ with Raspbian Stretch. But I have an error doing so...
pip3 install silkaj --user
Collecting silkaj
Using cached https://files.pythonhosted.org/packages/66/09/0a3e8d716924bd3d469dd3c2874f5c5269fed3d74d38b9191216d424deb5/silkaj-0.6.2-py3-none-any.whl
Collecting pyaes (from silkaj)
Using cached https://www.piwheels.org/simple/pyaes/pyaes-1.6.1-py3-none-any.whl
Collecting pynacl (from silkaj)
Using cached https://www.piwheels.org/simple/pynacl/PyNaCl-1.3.0-cp35-cp35m-linux_armv7l.whl
Collecting commandlines (from silkaj)
Using cached https://files.pythonhosted.org/packages/92/20/9fdf2c639119447ac03246ed3a04beb3c24aaf88d38f348e8c24375ec4aa/commandlines-0.4.1-py2.py3-none-any.whl
Collecting scrypt (from silkaj)
Using cached https://www.piwheels.org/simple/scrypt/scrypt-0.8.13-cp35-cp35m-linux_armv7l.whl
Collecting ipaddress (from silkaj)
Using cached https://files.pythonhosted.org/packages/fc/d0/7fc3a811e011d4b388be48a0e381db8d990042df54aa4ef4599a31d39853/ipaddress-1.0.22-py2.py3-none-any.whl
Collecting tabulate (from silkaj)
Using cached https://www.piwheels.org/simple/tabulate/tabulate-0.8.3-py3-none-any.whl
Collecting six (from pynacl->silkaj)
Using cached https://files.pythonhosted.org/packages/73/fb/00a976f728d0d1fecfe898238ce23f502a721c0ac0ecfedb80e0d88c64e9/six-1.12.0-py2.py3-none-any.whl
Collecting cffi>=1.4.1 (from pynacl->silkaj)
Using cached https://files.pythonhosted.org/packages/93/1a/ab8c62b5838722f29f3daffcc8d4bd61844aa9b5f437341cc890ceee483b/cffi-1.12.3.tar.gz
Collecting pycparser (from cffi>=1.4.1->pynacl->silkaj)
Using cached https://www.piwheels.org/simple/pycparser/pycparser-2.19-py2.py3-none-any.whl
Building wheels for collected packages: cffi
Running setup.py bdist_wheel for cffi ... error
Complete output from command /usr/bin/python3 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-0k8cfpyv/cffi/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/tmp28756jt5pip-wheel- --python-tag cp35:
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
No package 'libffi' 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
No package 'libffi' 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
No package 'libffi' 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
No package 'libffi' 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
No package 'libffi' found
running bdist_wheel
running build
running build_py
creating build
creating build/lib.linux-armv7l-3.5
creating build/lib.linux-armv7l-3.5/cffi
copying cffi/cparser.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/lock.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/cffi_opcode.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/ffiplatform.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/recompiler.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/verifier.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/__init__.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/pkgconfig.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/api.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/commontypes.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/backend_ctypes.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/vengine_cpy.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/model.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/error.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/setuptools_ext.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/vengine_gen.py -> build/lib.linux-armv7l-3.5/cffi
copying cffi/_cffi_include.h -> build/lib.linux-armv7l-3.5/cffi
copying cffi/parse_c_type.h -> build/lib.linux-armv7l-3.5/cffi
copying cffi/_embedding.h -> build/lib.linux-armv7l-3.5/cffi
copying cffi/_cffi_errors.h -> build/lib.linux-armv7l-3.5/cffi
running build_ext
building '_cffi_backend' extension
creating build/temp.linux-armv7l-3.5
creating build/temp.linux-armv7l-3.5/c
arm-linux-gnueabihf-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -g -fdebug-prefix-map=/build/python3.5-6waWnr/python3.5-3.5.3=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -DUSE__THREAD -DHAVE_SYNC_SYNCHRONIZE -I/usr/include/ffi -I/usr/include/libffi -I/usr/include/python3.5m -c c/_cffi_backend.c -o build/temp.linux-armv7l-3.5/c/_cffi_backend.o
c/_cffi_backend.c:15:17: fatal error: ffi.h: No such file or directory
#include <ffi.h>
^
compilation terminated.
error: command 'arm-linux-gnueabihf-gcc' failed with exit status 1
----------------------------------------
Failed building wheel for cffi
Running setup.py clean for cffi
Failed to build cffi