Add method to get a mounted session from config

Getting a session is great, but sometimes you need a thing called
an "adapter" which takes 5 parameters which are all already contained in
the config that you used to get the session.

Change-Id: Id4e418cd04ae81540d9898f7b2e959b974f355d2

os_client_config/__init__.py

@@ -13,3 +13,20 @@
 # under the License.
 
 from os_client_config.config import OpenStackConfig  # noqa
+
+
+def simple_client(service_key, cloud=None, region_name=None):
+    """Simple wrapper function. It has almost no features.
+
+    This will get you a raw requests Session Adapter that is mounted
+    on the given service from the keystone service catalog. If you leave
+    off cloud and region_name, it will assume that you've got env vars
+    set, but if you give them, it'll use clouds.yaml as you'd expect.
+
+    This function is deliberately simple. It has no flexibility. If you
+    want flexibility, you can make a cloud config object and call
+    get_session_client on it. This function is to make it easy to poke
+    at OpenStack REST APIs with a properly configured keystone session.
+    """
+    return OpenStackConfig().get_one_cloud(
+        cloud=cloud, region_name=region_name).get_session_client('compute')

os_client_config/cloud_config.py

@@ -14,6 +14,7 @@
 
 import warnings
 
+from keystoneauth1 import adapter
 from keystoneauth1 import plugin
 from keystoneauth1 import session
 
@@ -160,6 +161,28 @@ class CloudConfig(object):
                 timeout=self.config['api_timeout'])
         return self._keystone_session
 
+    def get_session_client(self, service_key):
+        """Return a prepped requests adapter for a given service.
+
+        This is useful for making direct requests calls against a
+        'mounted' endpoint. That is, if you do:
+
+          client = get_session_client('compute')
+
+        then you can do:
+
+          client.get('/flavors')
+
+        and it will work like you think.
+        """
+
+        return adapter.Adapter(
+            session=self.get_session(),
+            service_type=self.get_service_type(service_key),
+            service_name=self.get_service_name(service_key),
+            interface=self.get_interface(service_key),
+            region_name=self.region)
+
     def get_session_endpoint(self, service_key):
         """Return the endpoint from config or the catalog.