Require "requests[security]" if the `[tls]` option is selected, which also installs:

pyOpenSSL, cryptography, idna

and installs cryptography's version of openssl in Mac OS (which by default has an
ancient version of openssl that doesn't support TLS 1.2).
Signed-off-by: cyli <cyli@twistedmatrix.com>

README.md

@@ -10,6 +10,10 @@ The latest stable version [is available on PyPI](https://pypi.python.org/pypi/do
 
     pip install docker
 
+If you are intending to connect to a docker host via TLS, add `docker[tls]` to your requirements instead, or install with pip:
+
+    pip install docker[tls]
+
 ## Usage
 
 Connect to Docker using the default socket or the configuration in your environment:

requirements.txt

-requests==2.11.1
+requests[security]==2.11.1
 six>=1.4.0
 websocket-client==0.32.0
 backports.ssl_match_hostname>=3.5 ; python_version < '3.5'

setup.py

@@ -35,6 +35,16 @@ extras_require = {
     # ssl_match_hostname to verify hosts match with certificates via
     # ServerAltname: https://pypi.python.org/pypi/backports.ssl_match_hostname
     ':python_version < "3.3"': 'ipaddress >= 1.0.16',
+
+    # If using docker-py over TLS, highly recommend this option is pip-installed
+    # or pinned.
+
+    # TODO: if pip installign both "requests" and "requests[security]", the
+    # extra package from the "security" option are not installed (see
+    # https://github.com/pypa/pip/issues/4391).  Once that's fixed, instead of
+    # installing the extra dependencies, install the following instead:
+    # 'requests[security] >= 2.5.2, != 2.11.0, != 2.12.2'
+    'tls': ['pyOpenSSL>=0.14', 'cryptography>=1.3.4', 'idna>=2.0.0'],
 }
 
 version = None