consistent docstrings, config for services/spawner oauth_roles

jupyterhub/user.py

@@ -564,11 +564,16 @@ class User:
             oauth_client = oauth_provider.fetch_by_client_id(client_id)
             # create a new OAuth client + secret on every launch
             # containers that resume will be updated below
+
+            allowed_roles = spawner.oauth_roles
+            if callable(allowed_roles):
+                allowed_roles = allowed_roles(spawner)
+
             oauth_provider.add_client(
                 client_id,
                 api_token,
                 url_path_join(self.url, server_name, 'oauth_callback'),
-                allowed_roles=spawner.allowed_roles,
+                allowed_roles=allowed_roles,
                 description="Server at %s"
                 % (url_path_join(self.base_url, server_name) + '/'),
             )