Relax get_failed_containers() filter

When Ansible is run in check mode, the async_results are missing some
keys from regular runs, so we can't really tell if the container has
finished and failed; let's just skip it.

Closes-Bug: #1871397
Change-Id: I5f99c8e5392326fc8274ca3278966cddd49e0c3d

tripleo_ansible/ansible_plugins/filter/helpers.py

@@ -398,8 +398,13 @@ class FilterModule(object):
         """
         failed = []
         for item in async_results:
-            if item['failed'] or not item['finished']:
-                async_result_item = item['create_async_result_item']
-                for k, v in async_result_item['container_data'].items():
-                    failed.append(k)
+            try:
+                if item['failed'] or not item['finished']:
+                    async_result_item = item['create_async_result_item']
+                    for k, v in async_result_item['container_data'].items():
+                        failed.append(k)
+            except KeyError:
+                # if Ansible is run in check mode, the async_results items will
+                # not contain failed or finished keys.
+                continue
         return failed

tripleo_ansible/tests/plugins/filter/test_helpers.py

@@ -870,6 +870,15 @@ class TestHelperFilters(tests_base.TestCase):
                 "finished": 0,
                 "results_file": "/root/.ansible_async/316140143697.17616",
                 "started": 1
+            },
+            {
+                "ansible_job_id": "3161822143697.17616",
+                "ansible_loop_var": "container_data",
+                "changed": True,
+                "create_async_result_item": {},
+                "finished": 0,
+                "results_file": "/root/.ansible_async/316143697.17616",
+                "started": 1
             }
         ]
         expected_list = ['memcached', 'mysql']