Add support for loading proxy config from the environment

The popular python deployment platform PythonAnywhere requires that
http proxy settings be loaded from the environment when using their free plan
(to whitelist domains). This change adds a flag to enable loading this configuration.

Fixes #24

Author: jonathanlloyd

pusher_push_notifications/__init__.py

@@ -3,6 +3,7 @@
 import copy
 import datetime
 import json
+import os
 import re
 import time
 import warnings
@@ -76,12 +77,20 @@ def _make_url(scheme, host, path):
     ])
 
 
+def _get_proxies_from_env():
+    return {
+        'http': os.environ.get('HTTP_PROXY') or os.environ.get('http_proxy'),
+        'https': os.environ.get('HTTPS_PROXY') or os.environ.get('https_proxy'),
+    }
+
+
 class PushNotifications(object):
     """Pusher Push Notifications API client
     This client class can be used to publish notifications to the Pusher
     Push Notifications service"""
 
-    def __init__(self, instance_id, secret_key, endpoint=None):
+    def __init__(self, instance_id, secret_key,
+                 endpoint=None, use_proxy_env_vars=False):
         if not isinstance(instance_id, six.string_types):
             raise TypeError('instance_id must be a string')
         if instance_id == '':
@@ -99,6 +108,7 @@ def __init__(self, instance_id, secret_key, endpoint=None):
         self.instance_id = instance_id
         self.secret_key = secret_key
         self._endpoint = endpoint
+        self._use_proxy_env_vars = use_proxy_env_vars
 
     @property
     def endpoint(self):
@@ -117,6 +127,9 @@ def _make_request(self, method, path, path_params, body=None):
         url = _make_url(scheme='https', host=self.endpoint, path=path)
 
         session = requests.Session()
+        if self._use_proxy_env_vars:
+            session.proxies = _get_proxies_from_env()
+
         request = requests.Request(
             method,
             url,