Fixing cluster scale

The current implementation fails if we try to scale from different
node groups.

Change-Id: Ifb9e4b55959e10c9e5cb74c86bbdba9ffed50ceb

sahara/service/ops.py

@@ -327,10 +327,27 @@ def _provision_cluster(cluster_id):
     _refresh_health_for_cluster(cluster_id)
 
 
+def _specific_inst_to_delete(node_group, node_group_instance_map=None):
+    if node_group_instance_map:
+        if node_group.id in node_group_instance_map:
+            return True
+    return False
+
+
 @ops_error_handler(
     _("Scaling cluster failed for the following reason(s): {reason}"))
 def _provision_scaled_cluster(cluster_id, node_group_id_map,
                               node_group_instance_map=None):
+    """Provision scaled cluster.
+
+    :param cluster_id: Id of cluster to be scaled.
+
+    :param node_group_id_map: Dictionary in the format
+                   node_group_id: number of instances.
+
+    :param node_group_instance_map: Specifies the instances to be removed in
+                   each node group.
+    """
     ctx, cluster, plugin = _prepare_provisioning(cluster_id)
 
     # Decommissioning surplus nodes with the plugin
@@ -340,19 +357,25 @@ def _provision_scaled_cluster(cluster_id, node_group_id_map,
     try:
         instances_to_delete = []
         for node_group in cluster.node_groups:
+            ng_inst_to_delete_count = 0
+            # new_count is the new number of instance on the current node group
             new_count = node_group_id_map[node_group.id]
             if new_count < node_group.count:
-                if (node_group_instance_map and
-                        node_group.id in node_group_instance_map):
-                        for instance_ref in node_group_instance_map[
-                                node_group.id]:
-                            instance = _get_instance_obj(node_group.instances,
-                                                         instance_ref)
-                            instances_to_delete.append(instance)
+                # Adding selected instances to delete to the list
+                if _specific_inst_to_delete(node_group,
+                                            node_group_instance_map):
+                    for instance_ref in node_group_instance_map[node_group.id]:
+                        instances_to_delete.append(_get_instance_obj(
+                            node_group.instances, instance_ref))
+                        ng_inst_to_delete_count += 1
 
-                while node_group.count - new_count > len(instances_to_delete):
+                # Adding random instances to the list when the number of
+                # specific instances does not equals the difference between the
+                # current count and the new count of instances.
+                while node_group.count - new_count > ng_inst_to_delete_count:
                     instances_to_delete.append(_get_random_instance_from_ng(
                         node_group.instances, instances_to_delete))
+                    ng_inst_to_delete_count += 1
 
         if instances_to_delete:
             context.set_step_type(_("Plugin: decommission cluster"))

sahara/tests/unit/service/api/v2/base.py

@@ -85,7 +85,7 @@ SCALE_DATA_SPECIFIC_INSTANCE = {
         },
         {
             'name': 'ng_2',
-            'count': 2,
+            'count': 1,
             'instances': ['ng_2_0']
         }
     ],

sahara/tests/unit/service/api/v2/test_clusters.py

@@ -244,6 +244,37 @@ class TestClusterApi(base.SaharaWithDbTestCase):
              'ops.provision_scaled_cluster',
              'ops.terminate_cluster'], self.calls_order)
 
+    @mock.patch('sahara.service.quotas.check_cluster', return_value=None)
+    @mock.patch('sahara.service.quotas.check_scaling', return_value=None)
+    def test_scale_cluster_specific_and_non_specific(self, check_scaling,
+                                                     check_cluster):
+        cluster = api.create_cluster(api_base.SAMPLE_CLUSTER)
+        cluster = api.get_cluster(cluster.id)
+        api.scale_cluster(cluster.id, api_base.SCALE_DATA_SPECIFIC_INSTANCE)
+        result_cluster = api.get_cluster(cluster.id)
+        self.assertEqual('Scaled', result_cluster.status)
+        expected_count = {
+            'ng_1': 3,
+            'ng_2': 1,
+            'ng_3': 1,
+        }
+        ng_count = 0
+        for ng in result_cluster.node_groups:
+            self.assertEqual(expected_count[ng.name], ng.count)
+            ng_count += 1
+        self.assertEqual(1, result_cluster.node_groups[1].count)
+        self.assertNotIn('ng_2_0',
+                         self._get_instances_ids(
+                             result_cluster.node_groups[1]))
+        self.assertEqual(3, ng_count)
+        api.terminate_cluster(result_cluster.id)
+        self.assertEqual(
+            ['get_open_ports', 'recommend_configs', 'validate',
+             'ops.provision_cluster', 'get_open_ports',
+             'recommend_configs', 'validate_scaling',
+             'ops.provision_scaled_cluster',
+             'ops.terminate_cluster'], self.calls_order)
+
     def _get_instances_ids(self, node_group):
         instance_ids = []
         for instance in node_group.instances: