Add specific list method for NovaServer res

Nova API returns limited number of resources by one call. To clean all nova
servers, we should:
- list all pages(via marker option) [old novaclient].
- use limit=-1 and novaclient will list all pages for us.

Closes-Bug: #1490940
Change-Id: Ic4d2852d9fd7602ac99b08654d2f99c52adf1cfe

rally/plugins/openstack/context/cleanup/resources.py

@@ -61,6 +61,31 @@ _nova_order = get_order(200)
 
 @base.resource("nova", "servers", order=next(_nova_order))
 class NovaServer(base.ResourceManager):
+    def list(self):
+        """List all servers."""
+
+        if hasattr(self._manager().api, "api_version"):
+            # NOTE(andreykurilin): novaclient v2.27.0 includes ability to
+            #   return all servers(see https://review.openstack.org/#/c/217101
+            #   for more details). This release can be identified by presence
+            #   of "api_version" property of ``novaclient.client.Client`` cls.
+            return self._manager().list(limit=-1)
+        else:
+            # FIXME(andreykurilin): Remove code below, when minimum version of
+            #   novaclient in requirements will allow it.
+            # NOTE(andreykurilin): Nova API returns only limited number(
+            #   'osapi_max_limit' option in nova.conf) of servers, so we need
+            #   to use 'marker' option to list all pages of servers.
+            result = []
+            marker = None
+            while True:
+                servers = self._manager().list(marker=marker)
+                if not servers:
+                    break
+                result.extend(servers)
+                marker = servers[-1].id
+            return result
+
     def delete(self):
         if getattr(self.raw_resource, "OS-EXT-STS:locked", False):
             self.raw_resource.unlock()

tests/unit/plugins/openstack/context/cleanup/test_resources.py

@@ -84,6 +84,29 @@ class QuotaMixinTestCase(test.TestCase):
 
 class NovaServerTestCase(test.TestCase):
 
+    def test_list(self):
+        server = resources.NovaServer()
+        server._manager = mock.MagicMock()
+
+        server.list()
+
+        server._manager.return_value.list.assert_called_once_with(limit=-1)
+
+    def test_list_old_novaclient(self):
+        servers = [mock.MagicMock(), mock.MagicMock(), mock.MagicMock(),
+                   mock.MagicMock()]
+        server = resources.NovaServer()
+        server._manager = mock.MagicMock()
+        server._manager.return_value.api = None
+        server._manager.return_value.list.side_effect = (
+            servers[:2], servers[2:4], [])
+
+        self.assertEqual(servers, server.list())
+        self.assertEqual(
+            [mock.call(marker=None), mock.call(marker=servers[1].id),
+             mock.call(marker=servers[3].id)],
+            server._manager.return_value.list.call_args_list)
+
     def test_delete(self):
         server = resources.NovaServer()
         server.raw_resource = mock.Mock()