Configure TCP Keep-Alive for certain Sessions

If the user creates a keystoneclient.session.Session without passing a
custom session, we will enable TCP Keep-Alive for the requests session
used by keystoneclient's Session.

novaclient and other clients can experience hung TCP connections. Most
clients use keystoneclient's session and will need this merged here
before they can make use of it in their projects.

Change-Id: Ib70a8b3270d2492596b9fb8981b8584b85567a9c
Closes-bug: 1323862

keystoneclient/session.py

@@ -15,6 +15,7 @@ import functools
 import hashlib
 import logging
 import os
+import socket
 import time
 
 from oslo.config import cfg
@@ -123,6 +124,9 @@ class Session(object):
                  redirect=_DEFAULT_REDIRECT_LIMIT):
         if not session:
             session = requests.Session()
+            # Use TCPKeepAliveAdapter to fix bug 1323862
+            for scheme in session.adapters.keys():
+                session.mount(scheme, TCPKeepAliveAdapter())
 
         self.auth = auth
         self.session = session
@@ -778,3 +782,14 @@ class Session(object):
         kwargs['timeout'] = args.timeout
 
         return cls._make(**kwargs)
+
+
+class TCPKeepAliveAdapter(requests.adapters.HTTPAdapter):
+    """The custom adapter used to set TCP Keep-Alive on all connections."""
+    def init_poolmanager(self, *args, **kwargs):
+        if requests.__version__ >= '2.4.1':
+            kwargs.setdefault('socket_options', [
+                (socket.IPPROTO_TCP, socket.TCP_NODELAY, 1),
+                (socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1),
+            ])
+        super(TCPKeepAliveAdapter, self).init_poolmanager(*args, **kwargs)

keystoneclient/tests/test_session.py

@@ -205,6 +205,19 @@ class SessionTests(utils.TestCase):
         self.assertThat(self.requests.request_history,
                         matchers.HasLength(retries + 1))
 
+    def test_uses_tcp_keepalive_by_default(self):
+        session = client_session.Session()
+        requests_session = session.session
+        self.assertIsInstance(requests_session.adapters['http://'],
+                              client_session.TCPKeepAliveAdapter)
+        self.assertIsInstance(requests_session.adapters['https://'],
+                              client_session.TCPKeepAliveAdapter)
+
+    def test_does_not_set_tcp_keepalive_on_custom_sessions(self):
+        mock_session = mock.Mock()
+        client_session.Session(session=mock_session)
+        self.assertFalse(mock_session.mount.called)
+
 
 class RedirectTests(utils.TestCase):