ImportError：导入docker SDK for Python时没有名为ssl_match_hostname的模块

Question

为了使用Docker SDK for Python，我试图在Python脚本中import docker，但结果是ImportError带有以下回溯：

Traceback (most recent call last):
  File "/home/kurt/dev/clones8/ipercron-compose/furion/iclib/tests/test_utils/docker_utils.py", line 1, in <module>
    import docker
  File "/home/kurt/.local/lib/python2.7/site-packages/docker/__init__.py", line 6, in <module>
    from .client import Client, AutoVersionClient, from_env # flake8: noqa
  File "/home/kurt/.local/lib/python2.7/site-packages/docker/client.py", line 11, in <module>
    from . import api
  File "/home/kurt/.local/lib/python2.7/site-packages/docker/api/__init__.py", line 2, in <module>
    from .build import BuildApiMixin
  File "/home/kurt/.local/lib/python2.7/site-packages/docker/api/build.py", line 9, in <module>
    from .. import utils
  File "/home/kurt/.local/lib/python2.7/site-packages/docker/utils/__init__.py", line 2, in <module>
    from .utils import (
  File "/home/kurt/.local/lib/python2.7/site-packages/docker/utils/utils.py", line 19, in <module>
    from .. import tls
  File "/home/kurt/.local/lib/python2.7/site-packages/docker/tls.py", line 5, in <module>
    from .ssladapter import ssladapter
  File "/home/kurt/.local/lib/python2.7/site-packages/docker/ssladapter/__init__.py", line 1, in <module>
    from .ssladapter import SSLAdapter # flake8: noqa
  File "/home/kurt/.local/lib/python2.7/site-packages/docker/ssladapter/ssladapter.py", line 21, in <module>
    from backports.ssl_match_hostname import match_hostname
ImportError: No module named ssl_match_hostname
[Finished in 0.2s with exit code 1]
[shell_cmd: python -u "/home/kurt/dev/clones8/ipercron-compose/furion/iclib/tests/test_utils/docker_utils.py"]
[dir: /home/kurt/dev/clones8/ipercron-compose/furion/iclib/tests/test_utils]
[path: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin]

奇怪的是，导入在其他地方也起作用，例如在iPython提示符中：

Python 2.7.12 (default, Nov 19 2016, 06:48:10) 
Type "copyright", "credits" or "license" for more information.

IPython 2.4.1 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: import docker

In [2]: 

为什么在第一种情况下进口不起作用？

Answer 1

升级docker并不能解决我的问题。相反，我不得不将backports安装为Ubuntu包（并从pip卸载）：

sudo pip uninstall backports.ssl-match-hostname
sudo apt-get install python-backports.ssl-match-hostname

Answer 2

我在本地安装了backports.ssl-match-hostname，这使得它无法在系统级安装。我是通过

sudo pip uninstall backports.ssl-match-hostname

接

sudo pip install --upgrade docker

Answer 3

在Ubuntu/Debian上，目前存在一个与包升级（bug #893520）相关的bug，其中没有生成__init__.py文件。

检查以下文件是否存在：/usr/lib/python2.7/dist-packages/backports/__init__.py

如果它不存在并且安装了包python-backports.ssl-match-hostname，则运行以下命令以生成缺少的文件：

sudo pycompile -p python-backports.ssl-match-hostname