filters: make get_domain_id more robust

- Return None if no domain name was given
- Raise a KeyError if the domain name wasn't found so lookup couldn't
  happen.

Change-Id: Iec0009eab5ae33b9dda1ffbabc9fbfc83b2c5909

tripleo_ansible/ansible_plugins/filter/helpers.py

@@ -367,9 +367,12 @@ class FilterModule(object):
         This filter taks in input a domain name and a dictionary with all
         domain informations.
         """
+        if domain_name == '':
+            return
         for d in all_domains:
             if d.get('name') == domain_name:
                 return d.get('id')
+        raise KeyError('Could not get domain ID for "%s"' % domain_name)
 
     def get_changed_containers(self, async_results):
         """Return a list of containers that changed.

tripleo_ansible/roles/tripleo_keystone_resources/tasks/user_per_role.yml

@@ -21,7 +21,7 @@
     project: "{{ lookup('dict', tripleo_keystone_resources_data_user).value.project | default(omit) }}"
     # TODO(emilien) remove the custom filter once the module moved to OpenStack collections and we can make changes
     domain: >-
-      {{ lookup('dict', tripleo_keystone_resources_data_user).value.domain | default(omit) |
+      {{ lookup('dict', tripleo_keystone_resources_data_user).value.domain | default('') |
       get_domain_id(all_domains=openstack_domains) | default(omit) }}
     role: "{{ batched_tripleo_keystone_resources_roles_data.key }}"
     state: present

tripleo_ansible/tests/plugins/filter/test_helpers.py

@@ -777,6 +777,31 @@ class TestHelperFilters(tests_base.TestCase):
         result = self.filters.get_domain_id('heat_stack', openstack_domains)
         self.assertEqual(result, 'fd85b560d4554fd8bf363728e4a3863e')
 
+    def test_get_domain_id_empty(self):
+        openstack_domains = []
+        result = self.filters.get_domain_id('', openstack_domains)
+        self.assertEqual(result, None)
+
+    def test_get_domain_id_not_found(self):
+        openstack_domains = [
+            {
+                "description": "The default domain",
+                "enabled": "true",
+                "id": "default",
+                "name": "Default"
+            },
+            {
+                "description": "The heat stack domain",
+                "enabled": "true",
+                "id": "fd85b560d4554fd8bf363728e4a3863e",
+                "name": "heat_stack"
+            }
+        ]
+        self.assertRaises(
+            KeyError,
+            lambda: self.filters.get_domain_id('ghost', openstack_domains)
+        )
+
     def test_get_changed_containers(self):
         data = [
             {