Fix "prev" link pagination for instances with identical timestamps

This patch resolves an issue with the "prev" link when instances
have identical "created_at" values. This can occur when creating
instance using the "min/max count" option. The reverse sort does not
work correctly as the server list returned from nova is not an exact
reverse as the forward sort. It looks like the combination of sort_keys
must be unique to ensure the forward and reverse pagination properly.
As a workaround 'uuid' (server ID) is added to 'sort_keys'.
In addition, 'display_name' is added before 'uuid' in 'sort_keys'
to list servers in the alphabetical order (which sounds natural).

Closes-Bug #1856243
Change-Id: I73234b2c69ce8ea648b4a9721abe4f5670031909
(cherry picked from commit 9637d73374)

openstack_dashboard/api/nova.py

@@ -489,24 +489,38 @@ def server_list_paged(request,
         view_marker = 'possibly_deleted' if deleted and marker else 'ok'
         search_opts['marker'] = deleted if deleted else marker
         search_opts['limit'] = page_size + 1
-        search_opts['sort_dir'] = sort_dir
+        # NOTE(amotoki): It looks like the 'sort_keys' must be unique to make
+        # the pagination in the nova API works as expected. Multiple servers
+        # can have a same 'created_at' as its resolution is a second.
+        # To ensure the uniqueness we add 'uuid' to the sort keys.
+        # 'display_name' is added before 'uuid' to list servers in the
+        # alphabetical order.
+        sort_keys = ['created_at', 'display_name', 'uuid']
+
         servers = [Server(s, request)
-                   for s in nova_client.servers.list(detailed, search_opts)]
+                   for s in nova_client.servers.list(detailed, search_opts,
+                                                     sort_keys=sort_keys,
+                                                     sort_dirs=[sort_dir] * 3)]
+
         if view_marker == 'possibly_deleted':
             if not servers:
                 view_marker = 'head_deleted'
-                search_opts['sort_dir'] = 'desc'
                 reversed_order = False
                 servers = [Server(s, request)
-                           for s in nova_client.servers.list(detailed,
+                           for s in
-                                                             search_opts)]
+                           nova_client.servers.list(detailed,
+                                                    search_opts,
+                                                    sort_keys=sort_keys,
+                                                    sort_dirs=['desc'] * 3)]
             if not servers:
                 view_marker = 'tail_deleted'
-                search_opts['sort_dir'] = 'asc'
                 reversed_order = True
                 servers = [Server(s, request)
-                           for s in nova_client.servers.list(detailed,
+                           for s in
-                                                             search_opts)]
+                           nova_client.servers.list(detailed,
+                                                    search_opts,
+                                                    sort_keys=sort_keys,
+                                                    sort_dirs=['asc'] * 3)]
         (servers, has_more_data, has_prev_data) = update_pagination(
             servers, page_size, marker, reversed_order)
         has_prev_data = (False

openstack_dashboard/test/unit/api/test_nova.py

@@ -204,8 +204,9 @@ class ComputeApiTests(test.APIMockTestCase):
             True,
             {'all_tenants': True,
              'marker': None,
-             'limit': page_size + 1,
+             'limit': page_size + 1},
-             'sort_dir': 'desc'})
+            sort_dirs=['desc', 'desc', 'desc'],
+            sort_keys=['created_at', 'display_name', 'uuid'])
 
     @override_settings(API_RESULT_PAGE_SIZE=1)
     @mock.patch.object(api._nova, 'novaclient')
@@ -230,8 +231,9 @@ class ComputeApiTests(test.APIMockTestCase):
             True,
             {'all_tenants': True,
              'marker': None,
-             'limit': page_size + 1,
+             'limit': page_size + 1},
-             'sort_dir': 'desc'})
+            sort_dirs=['desc', 'desc', 'desc'],
+            sort_keys=['created_at', 'display_name', 'uuid'])
 
     @mock.patch.object(api._nova, 'novaclient')
     def test_usage_get(self, mock_novaclient):