Python pip install requires server_hostname

Question

I finished installing pip on linux, the pip list command works. But when using the pip install command it got the following error:

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/basecommand.py", line 232, in main
    status = self.run(options, args)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/commands/install.py", line 339, in run
    requirement_set.prepare_files(finder)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/req/req_set.py", line 333, in prepare_files
    upgrade=self.upgrade,
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/index.py", line 305, in find_requirement
    page = self._get_page(main_index_url, req)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/index.py", line 783, in _get_page
    return HTMLPage.get_page(link, req, session=self.session)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/index.py", line 872, in get_page
    "Cache-Control": "max-age=600",
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/sessions.py", line 473, in get
    return self.request('GET', url, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/download.py", line 365, in request
    return super(PipSession, self).request(method, url, *args, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/sessions.py", line 461, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/sessions.py", line 573, in send
    r = adapter.send(request, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/cachecontrol/adapter.py", line 43, in send
    resp = super(CacheControlAdapter, self).send(request, **kw)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/adapters.py", line 370, in send
    timeout=timeout
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/packages/urllib3/connectionpool.py", line 518, in urlopen
    body=body, headers=headers)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/packages/urllib3/connectionpool.py", line 322, in _make_request
    self._validate_conn(conn)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/packages/urllib3/connectionpool.py", line 727, in _validate_conn
    conn.connect()
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/packages/urllib3/connection.py", line 238, in connect
    ssl_version=resolved_ssl_version)
  File "/usr/local/lib/python2.7/site-packages/pip-6.0.7-py2.7.egg/pip/_vendor/requests/packages/urllib3/util/ssl_.py", line 254, in ssl_wrap_socket
    return context.wrap_socket(sock)
  File "/usr/local/lib/python2.7/ssl.py", line 350, in wrap_socket
    _context=self)
  File "/usr/local/lib/python2.7/ssl.py", line 537, in __init__
    raise ValueError("check_hostname requires server_hostname")
ValueError: check_hostname requires server_hostname

How can I fix this?

Answer 1

pip 6.1.0 has been released, fixing this issue. You can upgrade with:

pip --trusted-host pypi.python.org install -U pip

to self-upgrade.

---

Original answer:

This is caused by a change in Python 2.7.9, which urllib3 needs to account for. See issue #543 for that project. Your OpenSSL libraries do not support SNI, which means urllib3 won't pass in the host name to the SSL socket wrapper, but Python 2.7.9 expects the hostname to be passed in anyway for different purposes.

urllib3 is indirectly used by requests (see requests issue 2435), which in turn is being used by pip.

I've opened a ticket to track this from pip's perspective.

The underlying issues have been fixed by the project maintainers, and awaiting a new release. You could install the current development version of pip if you are impatient:

pip install --trusted-host=github.com -U https://github.com/pypa/pip/archive/develop.zip

This'll install pip-6.1.0.dev0, when 6.1.0 is fully released you can upgrade again with pip install -U pip to get the final release from PyPI.

Answer 2

I get the same issue, and find that it can be avoided (pip 6.0.8) in my case as follows

pip --trusted-host pypi.python.org install <thing>