Allow parameter expansion in endpoint_override

Allow %(project_id)s and %(user_id)s in an endpoint_override string to
be replaced with the appropriate values from the authentication. This
makes it easier to use and specify overrides from the command line or
scripts where we may not know the project_id/user_id ahead of time.

Change-Id: Ia09f5a88cb6590113dab26796c58e708014e98f7
Closes-Bug: #1536874

keystoneauth1/session.py

@@ -71,6 +71,28 @@ class _JSONEncoder(json.JSONEncoder):
         return super(_JSONEncoder, self).default(o)
 
 
+class _StringFormatter(object):
+    """A String formatter that fetches values on demand"""
+
+    def __init__(self, session, auth):
+        self.session = session
+        self.auth = auth
+
+    def __getitem__(self, item):
+        if item == 'project_id':
+            value = self.session.get_project_id(self.auth)
+        elif item == 'user_id':
+            value = self.session.get_user_id(self.auth)
+        else:
+            raise AttributeError(item)
+
+        if not value:
+            raise ValueError("This type of authentication does not provide a "
+                             "%s that can be substituted" % item)
+
+        return value
+
+
 class Session(object):
     """Maintains client communication state and common functionality.
 
@@ -302,7 +324,11 @@ class Session(object):
                                       endpoint in the auth plugin. This will be
                                       ignored if a fully qualified URL is
                                       provided but take priority over an
-                                      endpoint_filter. (optional)
+                                      endpoint_filter. This string may contain
+                                      the values %(project_id)s and %(user_id)s
+                                      to have those values replaced by the
+                                      project_id/user_id of the current
+                                      authentication. (optional)
         :param auth: The auth plugin to use when authenticating this request.
                      This will override the plugin that is attached to the
                      session (if any). (optional)
@@ -360,7 +386,7 @@ class Session(object):
             base_url = None
 
             if endpoint_override:
-                base_url = endpoint_override
+                base_url = endpoint_override % _StringFormatter(self, auth)
             elif endpoint_filter:
                 base_url = self.get_endpoint(auth, **endpoint_filter)
 

keystoneauth1/tests/unit/test_session.py

@@ -25,6 +25,7 @@ from keystoneauth1 import exceptions
 from keystoneauth1 import plugin
 from keystoneauth1 import session as client_session
 from keystoneauth1.tests.unit import utils
+from keystoneauth1 import token_endpoint
 
 
 class SessionTests(utils.TestCase):
@@ -366,12 +367,16 @@ class AuthPlugin(plugin.BaseAuthPlugin):
 class CalledAuthPlugin(plugin.BaseAuthPlugin):
 
     ENDPOINT = 'http://fakeendpoint/'
+    USER_ID = uuid.uuid4().hex
+    PROJECT_ID = uuid.uuid4().hex
 
     def __init__(self, invalidate=True):
         self.get_token_called = False
         self.get_endpoint_called = False
         self.endpoint_arguments = {}
         self.invalidate_called = False
+        self.get_project_id_called = False
+        self.get_user_id_called = False
         self._invalidate = invalidate
 
     def get_token(self, session):
@@ -387,6 +392,14 @@ class CalledAuthPlugin(plugin.BaseAuthPlugin):
         self.invalidate_called = True
         return self._invalidate
 
+    def get_project_id(self, session, **kwargs):
+        self.get_project_id_called = True
+        return self.PROJECT_ID
+
+    def get_user_id(self, session, **kwargs):
+        self.get_user_id_called = True
+        return self.USER_ID
+
 
 class SessionAuthTests(utils.TestCase):
 
@@ -574,6 +587,9 @@ class SessionAuthTests(utils.TestCase):
         self.assertTrue(auth.get_token_called)
         self.assertFalse(auth.get_endpoint_called)
 
+        self.assertFalse(auth.get_user_id_called)
+        self.assertFalse(auth.get_project_id_called)
+
     def test_endpoint_override_ignore_full_url(self):
         auth = CalledAuthPlugin()
         sess = client_session.Session(auth=auth)
@@ -594,6 +610,70 @@ class SessionAuthTests(utils.TestCase):
         self.assertTrue(auth.get_token_called)
         self.assertFalse(auth.get_endpoint_called)
 
+        self.assertFalse(auth.get_user_id_called)
+        self.assertFalse(auth.get_project_id_called)
+
+    def test_endpoint_override_does_id_replacement(self):
+        auth = CalledAuthPlugin()
+        sess = client_session.Session(auth=auth)
+
+        override_base = 'http://mytest/%(project_id)s/%(user_id)s'
+        path = 'path'
+        replacements = {'user_id': CalledAuthPlugin.USER_ID,
+                        'project_id': CalledAuthPlugin.PROJECT_ID}
+        override_url = override_base % replacements + '/' + path
+        resp_text = uuid.uuid4().hex
+
+        self.requests_mock.get(override_url, text=resp_text)
+
+        resp = sess.get(path,
+                        endpoint_override=override_base,
+                        endpoint_filter={'service_type': 'identity'})
+
+        self.assertEqual(resp_text, resp.text)
+        self.assertEqual(override_url, self.requests_mock.last_request.url)
+
+        self.assertTrue(auth.get_token_called)
+        self.assertTrue(auth.get_user_id_called)
+        self.assertTrue(auth.get_project_id_called)
+        self.assertFalse(auth.get_endpoint_called)
+
+    def test_endpoint_override_fails_to_replace_if_none(self):
+        # The token_endpoint plugin doesn't know user_id or project_id
+        auth = token_endpoint.Token(uuid.uuid4().hex, uuid.uuid4().hex)
+        sess = client_session.Session(auth=auth)
+
+        override_base = 'http://mytest/%(project_id)s'
+
+        e = self.assertRaises(ValueError,
+                              sess.get,
+                              '/path',
+                              endpoint_override=override_base,
+                              endpoint_filter={'service_type': 'identity'})
+
+        self.assertIn('project_id', str(e))
+        override_base = 'http://mytest/%(user_id)s'
+
+        e = self.assertRaises(ValueError,
+                              sess.get,
+                              '/path',
+                              endpoint_override=override_base,
+                              endpoint_filter={'service_type': 'identity'})
+        self.assertIn('user_id', str(e))
+
+    def test_endpoint_override_fails_to_do_unknown_replacement(self):
+        auth = CalledAuthPlugin()
+        sess = client_session.Session(auth=auth)
+
+        override_base = 'http://mytest/%(unknown_id)s'
+
+        e = self.assertRaises(AttributeError,
+                              sess.get,
+                              '/path',
+                              endpoint_override=override_base,
+                              endpoint_filter={'service_type': 'identity'})
+        self.assertIn('unknown_id', str(e))
+
     def test_user_and_project_id(self):
         auth = AuthPlugin()
         sess = client_session.Session(auth=auth)