Python3.7入れる時に `No module named '_ctypes'` エラー

Python3.6までは問題なくビルドできたのに3.7で _ctypes のエラーがでてビルドできないといった嘆きをよく見ます。

$ pipenv --python 3.7.2
Warning: Python 3.7.2 was not found on your system…
Would you like us to install CPython 3.7.2 with pyenv? [Y/n]: Y
Installing CPython 3.7.2 with pyenv (this may take a few minutes)…
✘ Failed...
Something went wrong…
Downloading Python-3.7.2.tar.xz...
-> https://www.python.org/ftp/python/3.7.2/Python-3.7.2.tar.xz
Installing Python-3.7.2...

BUILD FAILED (CentOS Linux 7 using python-build 20180424)

Inspect or clean up the working tree at /tmp/python-build.20190405065753.24551
Results logged to /tmp/python-build.20190405065753.24551.log

Last 10 log lines:
  File "/tmp/tmpregj5qs2/pip-18.1-py2.py3-none-any.whl/pip/_internal/commands/__init__.py", line 6, in <module>
  File "/tmp/tmpregj5qs2/pip-18.1-py2.py3-none-any.whl/pip/_internal/commands/completion.py", line 6, in <module>
  File "/tmp/tmpregj5qs2/pip-18.1-py2.py3-none-any.whl/pip/_internal/cli/base_command.py", line 18, in <module>
  File "/tmp/tmpregj5qs2/pip-18.1-py2.py3-none-any.whl/pip/_internal/download.py", line 38, in <module>
  File "/tmp/tmpregj5qs2/pip-18.1-py2.py3-none-any.whl/pip/_internal/utils/glibc.py", line 3, in <module>
  File "/tmp/python-build.20190405065753.24551/Python-3.7.2/Lib/ctypes/__init__.py", line 7, in <module>
    from _ctypes import Union, Structure, Array
ModuleNotFoundError: No module named '_ctypes'
make[1]: *** [install] Error 1
make[1]: Leaving directory `/tmp/python-build.20190405065753.24551/Python-3.7.2'

Warning: The Python you just installed is not available on your PATH, apparently.
make: *** [setup] Error 1

libffi をインストールすると良いようです。
CentOS系列だと以下のコマンドでインストールできます。

$ sudo yum install libffi-devel

理由は公式ドキュメントに載ってました。

docs.python.org

A full copy of libffi is no longer bundled for use when building the ctypes module on non-OSX UNIX platforms. An installed copy of libffi is now required when building ctypes on such platforms. (Contributed by Zachary Ware in bpo-27979.)

今回から必要だよって感じの事を言ってます。

また、下記からOpenSSLのバージョンが古すぎてもダメそうですね。

The ssl module requires OpenSSL 1.0.2 or 1.1 compatible libssl. OpenSSL 1.0.1 has reached end of lifetime on 2016-12-31 and is no longer supported. LibreSSL is temporarily not supported as well. LibreSSL releases up to version 2.6.4 are missing required OpenSSL 1.0.2 APIs.

Python3.7は現行最新のPythonです。（執筆時2019/04/06)
アップデートして良いPythonライフを送ってください。

続報

やっぱりOpenSSLのエラーに遭遇しました。

saruhei1989.hatenablog.com