Make list_projects a method of auth plugin

Federation plugins and possibly others in the future need the ability to
customize how they retrieve projects from the keystone server. By making
it a method of the plugin it can be overridden by these plugins.

Change-Id: Ide2fd4edc7eb2d61fe95166ec9cbce9c2753c616

2 files changed, 45 insertions, 15 deletions

diff --git a/openstack_auth/backend.py b/openstack_auth/backend.py
index 8fb0d40..cc97c0a 100644
--- a/openstack_auth/backend.py
+++ b/openstack_auth/backend.py
@@ -119,21 +119,9 @@ class KeystoneBackend(object):
         # Check expiry for our unscoped auth ref.
         self.check_auth_expiry(unscoped_auth_ref)
 
-        unscoped_client = keystone_client_class(session=session,
-                                                auth=unscoped_auth)
-
-        # We list all the user's projects
-        try:
-            if utils.get_keystone_version() >= 3:
-                projects = unscoped_client.projects.list(
-                    user=unscoped_auth_ref.user_id)
-            else:
-                projects = unscoped_client.tenants.list()
-        except (keystone_exceptions.ClientException,
-                keystone_exceptions.AuthorizationFailure) as exc:
-            msg = _('Unable to retrieve authorized projects.')
-            raise exceptions.KeystoneAuthException(msg)
-
+        projects = plugin.list_projects(session,
+                                        unscoped_auth,
+                                        unscoped_auth_ref)
         # Attempt to scope only to enabled projects
         projects = [project for project in projects if project.enabled]
 
diff --git a/openstack_auth/plugin/base.py b/openstack_auth/plugin/base.py
index 83eae09..bd0b200 100644
--- a/openstack_auth/plugin/base.py
+++ b/openstack_auth/plugin/base.py
@@ -12,8 +12,12 @@
 
 import abc
 
+from keystoneclient import exceptions as keystone_exceptions
+from keystoneclient.v2_0 import client as v2_client
+from keystoneclient.v3 import client as v3_client
 import six
 
+from openstack_auth import exceptions
 from openstack_auth import utils
 
 __all__ = ['BasePlugin']
@@ -49,3 +53,41 @@ class BasePlugin(object):
     def keystone_version(self):
         """The Identity API version as specified in the settings file."""
         return utils.get_keystone_version()
+
+    def list_projects(self, session, auth_plugin, auth_ref=None):
+        """List the projects that are accessible to this plugin.
+
+        Query the keystone server for all projects that this authentication
+        token can be rescoped to.
+
+        This function is overrideable by plugins if they use a non-standard
+        mechanism to determine projects.
+
+        :param session: A session object for communication:
+        :type session: keystoneclient.session.Session
+        :param auth_plugin: The auth plugin returned by :py:meth:`get_plugin`.
+        :type auth_plugin: keystoneclient.auth.BaseAuthPlugin
+        :param auth_ref: The current authentication data. This is optional as
+                         future auth plugins may not have auth_ref data and all
+                         the required information should be available via the
+                         auth_plugin.
+        :type auth_ref: keystoneclient.access.AccessInfo` or None.
+
+        :raises: exceptions.KeystoneAuthException on lookup failure.
+
+        :returns: A list of projects. This currently accepts returning both v2
+                  or v3 keystoneclient projects objects.
+        """
+        try:
+            if self.keystone_version >= 3:
+                client = v3_client.Client(session=session, auth=auth_plugin)
+                return client.projects.list(user=auth_ref.user_id)
+
+            else:
+                client = v2_client.Client(session=session, auth=auth_plugin)
+                return client.tenants.list()
+
+        except (keystone_exceptions.ClientException,
+                keystone_exceptions.AuthorizationFailure):
+            msg = _('Unable to retrieve authorized projects.')
+            raise exceptions.KeystoneAuthException(msg)