Send keystoneauth a better user-agent string

When we moved to keystoneauth sessions from our own handwritten session
class, we lost the nice user-agent string we built up. That was then
added to keystoneauth and has now been released in version 2.2.0, which
we picked up. That implementation provides a good base for us to build
on, and we should now send our own version string as well as make way
for callers to submit their application's name/version string as well.

Change-Id: I439b0912b27a37c4ddfc91447a5f3394df2d0385

openstack/session.py

@@ -20,7 +20,9 @@ from six.moves.urllib import parse
 
 from keystoneauth1 import session as _session
 
+import openstack
 
+DEFAULT_USER_AGENT = "openstacksdk/%s" % openstack.__version__
 VERSION_PATTERN = re.compile('/v\d[\d.]*')
 
 
@@ -40,16 +42,27 @@ def parse_url(filt, url):
 
 class Session(_session.Session):
 
-    def __init__(self, profile, **kwargs):
+    def __init__(self, profile, user_agent=None, **kwargs):
         """Create a new Keystone auth session with a profile.
 
         :param profile: If the user has any special profiles such as the
             service name, region, version or interface, they may be provided
             in the profile object.  If no profiles are provided, the
             services that appear first in the service catalog will be used.
+        :param user_agent: A User-Agent header string to use for the
+                           request. If not provided, a default of
+                           :attr:`~openstack.session.DEFAULT_USER_AGENT`
+                           is used, which contains the openstacksdk version
+                           When a non-None value is passed, it will be
+                           prepended to the default.
         :type profile: :class:`~openstack.profile.Profile`
         """
-        super(Session, self).__init__(**kwargs)
+        if user_agent is not None:
+            self.user_agent = "%s %s" % (user_agent, DEFAULT_USER_AGENT)
+        else:
+            self.user_agent = DEFAULT_USER_AGENT
+        super(Session, self).__init__(user_agent=self.user_agent, **kwargs)
+
         self.profile = profile
 
     def get_endpoint(self, auth=None, interface=None, **kwargs):

openstack/tests/unit/test_session.py

@@ -33,3 +33,11 @@ class TestSession(testtools.TestCase):
         self.assertEqual(
             "http://127.0.0.1:9292/wot/v1/mytenant",
             session.parse_url(filt, "http://127.0.0.1:9292/wot/v2.0/mytenant"))
+
+    def test_user_agent_none(self):
+        sot = session.Session(None)
+        self.assertTrue(sot.user_agent.startswith("openstacksdk"))
+
+    def test_user_agent_set(self):
+        sot = session.Session(None, user_agent="testing/123")
+        self.assertTrue(sot.user_agent.startswith("testing/123 openstacksdk"))