Fix MariaDB clusters failing with TypeError

This would apply to any type of cluster that uses the galera strategy
while setting the nics on a create call. When we called cast to set()
the object was a list of lists. The set method can not has a list so
this was causesing a unhashable error.

The change is to make the instance_nics a list of strings (what we
originaly expected) to resolve this issue.

Change-Id: I6b04f8b580720e5791e0977a9347d031cdbf9710
Closes-Bug: #1570602

releasenotes/notes/fix-cluster-type-error-71cd846897dfd32e.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - This would apply to any type of cluster that uses the galera strategy
+    while setting the nics on a create call. When we called cast to set()
+    the object was a list of lists. The set method can not has a list so
+    this was causesing a unhashable error. The change is to make the
+    instance_nics a list of strings (what we originaly expected) to
+    resolve this issue. Bug 1570602.

trove/common/strategies/cluster/experimental/galera_common/api.py

@@ -98,12 +98,16 @@ class GaleraCommonCluster(cluster_models.Cluster):
         check_quotas(context.tenant, deltas)
 
         # Checking networks are same for the cluster
-        instance_nics = [instance.get('nics', None) for instance in instances]
-        if len(set(instance_nics)) != 1:
+        instance_nics = []
+        for instance in instances:
+            nics = instance.get('nics')
+            if nics:
+                instance_nics.append(nics[0].get('net-id'))
+        if len(set(instance_nics)) > 1:
             raise exception.ClusterNetworksNotEqual()
-        instance_nic = instance_nics[0]
-        if instance_nic is None:
+        if not instance_nics:
             return
+        instance_nic = instance_nics[0]
         try:
             nova_client.networks.get(instance_nic)
         except nova_exceptions.NotFound:

trove/tests/unittests/cluster/test_galera_cluster.py

@@ -65,9 +65,13 @@ class ClusterTest(trove_testtools.TestCase):
         self.datastore_version = self.dv
         self.cluster = galera_api.GaleraCommonCluster(
             self.context, self.db_info, self.datastore, self.datastore_version)
-        self.instances = [{'volume_size': 1, 'flavor_id': '1234'},
-                          {'volume_size': 1, 'flavor_id': '1234'},
-                          {'volume_size': 1, 'flavor_id': '1234'}]
+        self.instances = [
+            {'volume_size': 1, 'flavor_id': '1234',
+             'nics': [{"net-id": "foo-bar"}]},
+            {'volume_size': 1, 'flavor_id': '1234',
+             'nics': [{"net-id": "foo-bar"}]},
+            {'volume_size': 1, 'flavor_id': '1234',
+             'nics': [{"net-id": "foo-bar"}]}]
 
     def tearDown(self):
         super(ClusterTest, self).tearDown()