Mycroft-core: Installer Python script/s fail. -- No module named '_ctypes'.

Seems to be a work-around here. But this is still a bug.
https://stackoverflow.com/questions/27022373/python3-importerror-no-module-named-ctypes-when-using-value-from-module-mul

on Raspbian, this could be added to the install script:

Git is already installed. So download the git repo into a 'cpython' subdirectory inside the 'mycroft-core' directory via git:

git clone https://github.com/python/cpython.git

And build and compile it:

cd cpython

./configure
make -j 4
sudo make altinstall

cd ..

If git is not installed, (since this script runs on all Linux), consider this before git clone:
Install from source:
https://git-scm.com/book/en/v2/Getting-Started-Installing-Git

New problem:

After compiling and installing cpython, The start-mycroft.sh script still fails, but continues after failing:

Traceback (most recent call last):
  File "<stdin>", line 20649, in <module>
  File "<stdin>", line 197, in main
  File "<stdin>", line 82, in bootstrap
  File "/tmp/tmpy509z2ho/pip.zip/pip/_internal/__init__.py", line 42, in <module>
  File "/tmp/tmpy509z2ho/pip.zip/pip/_internal/cmdoptions.py", line 16, in <module>
  File "/tmp/tmpy509z2ho/pip.zip/pip/_internal/index.py", line 25, in <module>
  File "/tmp/tmpy509z2ho/pip.zip/pip/_internal/download.py", line 39, in <module>
  File "/tmp/tmpy509z2ho/pip.zip/pip/_internal/utils/glibc.py", line 3, in <module>
  File "/usr/local/lib/python3.7/ctypes/__init__.py", line 7, in <module>
    from _ctypes import Union, Structure, Array
ModuleNotFoundError: No module named '_ctypes'
Failed to set up virtualenv for mycroft, exiting setup.
start-mycroft.sh:  Mycroft command/service launcher
usage: start-mycroft.sh [COMMAND] [restart] [params]

Services COMMANDs:
  all                      runs core services: bus, audio, skills, voice
  debug                    runs core services, then starts the CLI
  audio                    the audio playback service
  bus                      the messagebus service
  skills                   the skill service
  voice                    voice capture service
  enclosure                mark_1 enclosure service

Tool COMMANDs:
  cli                      the Command Line Interface
  unittest                 run mycroft-core unit tests (requires pytest)
  skillstest               run the skill autotests for all skills (requires pytest)

Util COMMANDs:
  audiotest                attempt simple audio validation
  audioaccuracytest        more complex audio validation
  sdkdoc                   generate sdk documentation

Options:
  restart                  (optional) Force the service to restart if running

Examples:
  start-mycroft.sh all
  start-mycroft.sh all restart
  start-mycroft.sh cli
  start-mycroft.sh unittest

It acts like it's installed, after failing.

When attempting to use ./start-mycroft.sh debug, it fails with multiple errors:

ModuleNotFoundError: No module named '_ctypes'
Failed to set up virtualenv for mycroft, exiting setup.

Starting all mycroft-core services
Initializing...
Starting background service bus
CAUTION: The Mycroft bus is an open websocket with no built-in security
         measures.  You are responsible for protecting the local port
         8181 with a firewall as appropriate.
./start-mycroft.sh: line 140: /var/log/mycroft/bus.log: No such file or directory
Starting background service skills
./start-mycroft.sh: line 140: /var/log/mycroft/skills.log: No such file or directory
Starting background service audio
./start-mycroft.sh: line 140: /var/log/mycroft/audio.log: No such file or directory
Starting background service voice
./start-mycroft.sh: line 140: /var/log/mycroft/voice.log: No such file or directory
Starting background service enclosure
./start-mycroft.sh: line 140: /var/log/mycroft/enclosure.log: No such file or directory
Starting cli
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/runpy.py", line 183, in _run_module_as_main
    mod_name, mod_spec, code = _get_module_details(mod_name, _Error)
  File "/usr/local/lib/python3.7/runpy.py", line 109, in _get_module_details
    __import__(pkg_name)
  File "/home/pi/Mycroft/mycroft-core/mycroft/__init__.py", line 17, in <module>
    from mycroft.api import Api
  File "/home/pi/Mycroft/mycroft-core/mycroft/api/__init__.py", line 18, in <module>
    import requests
ModuleNotFoundError: No module named 'requests'

Guessing you're not using picroft, which just works.

      Guessing you're not using picroft, which just works.

Correct. Because I like doing other things with my Rpi in a GUI environment too, and Picroft failed to run properly and didn't detect a basic USB microphone. Can't report bugs without a GUI

This is a really weird issue. Seems like the python environment on your device isn't quite working or something? _ctypes is included in the local python standard library which is used to create the mycroft virtualenv.

Can you try to delete the .venv folder in the mycroft-core directory rm -rf .venv and then rerun the dev_setup.sh script?

Hi, since there's been no communication on this issue for 4 months I'm going to close it. If you're still experiencing this problem feel free to reopen the issue.

I found answer here, Zachary Ware's answer. I used yum install libffi-dev to fix it.

I found answer here, Zachary Ware's answer. I used yum install libffi-dev to fix it.

Yes that worked for me, I made sure these packages are installed on my Centos 7:

sudo yum install -y zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel expat-devel libffi-dev gcc gcc-c++ zlib libffi-devel

Then reinstalled my python 3.8.1:

wget http://python.org/ftp/python/3.6.8/Python-3.6.8.tar.xz

tar xf Python-3.6.8.tar.xz

cd Python-3.6.8

./configure --prefix=/usr/local --enable-shared LDFLAGS="-Wl,-rpath /usr/local/lib"

make && make altinstall

Then I was finally able to install docker-compose:

pip3.8 install docker-compose

Thanks @grossshen