Cleanup session on delete

If an external session object was not passed to the Session class, we
create a requests.Session() on our own. Once this is used, it may still
have an open connection when the auth Session is closed. We need to
handle the closing of the requests.Session() ourselves if we created
one. If you do not close it, a ResourceWarning may be reported about the
socket that is left open. If a session object is provided, we do not
attempt to close it as it will be up to the code consuming keystoneauth
to properly handle cleaning up the provided session.

Change-Id: I590755d665b371c76ba8e02836d81d41a95ac601
Closes-Bug: #1838704

keystoneauth1/session.py

@@ -347,6 +347,13 @@ class Session(object):
 
         self.auth = auth
         self.session = _construct_session(session)
+        # NOTE(mwhahaha): keep a reference to the session object so we can
+        # clean it up when this object goes away. We don't want to close the
+        # session if it was passed into us as it may be reused externally.
+        # See LP#1838704
+        self._session = None
+        if not session:
+            self._session = self.session
         self.original_ip = original_ip
         self.verify = verify
         self.cert = cert
@@ -375,6 +382,17 @@ class Session(object):
 
         self._json = _JSONEncoder()
 
+    def __del__(self):
+        """Clean up resources on delete."""
+        if self._session:
+            # If we created a requests.Session, try to close it out correctly
+            try:
+                self._session.close()
+            except Exception:
+                pass
+            finally:
+                self._session = None
+
     @property
     def adapters(self):
         return self.session.adapters

keystoneauth1/tests/unit/test_session.py

@@ -930,6 +930,14 @@ class SessionAuthTests(utils.TestCase):
 
         self.assertRequestHeaderEqual('X-Auth-Token', None)
 
+    def test_object_delete(self):
+        auth = AuthPlugin()
+        sess = client_session.Session(auth=auth)
+        mock_close = mock.Mock()
+        sess._session.close = mock_close
+        del sess
+        mock_close.assert_called_once()
+
     def test_service_type_urls(self):
         service_type = 'compute'
         interface = 'public'

releasenotes/notes/cleanup-session-on-delete-1ed6177d4c5c1f83.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - >
+    [`bug 1838704 <https://bugs.launchpad.net/keystone/+bug/1838704>`_]
+    When consuming keystoneauth1.session.Session, if a requests session is not
+    provided one is created. The Session used for requests may result in a
+    ResourceWarning being generated if it is not properly closed. The code
+    has been updated to close the session correctly when the Session object
+    is deleted.