Fix copy API

In web/task split deployment web and task container no longer share the same redis cache

In the original code we use redis cache to pass the list of sub objects that need to be copied to the new object

In this PR we extracted out the logic that computes the sub_object_list and move it into deep_copy_model_obj task

awx/main/tasks/system.py

@@ -893,15 +893,8 @@ def _reconstruct_relationships(copy_mapping):
 
 
 @task(queue=get_task_queuename)
-def deep_copy_model_obj(model_module, model_name, obj_pk, new_obj_pk, user_pk, uuid, permission_check_func=None):
-    sub_obj_list = cache.get(uuid)
-    if sub_obj_list is None:
-        logger.error('Deep copy {} from {} to {} failed unexpectedly.'.format(model_name, obj_pk, new_obj_pk))
-        return
-
+def deep_copy_model_obj(model_module, model_name, obj_pk, new_obj_pk, user_pk, permission_check_func=None):
     logger.debug('Deep copy {} from {} to {}.'.format(model_name, obj_pk, new_obj_pk))
-    from awx.api.generics import CopyAPIView
-    from awx.main.signals import disable_activity_stream
 
     model = getattr(importlib.import_module(model_module), model_name, None)
     if model is None:
@@ -913,6 +906,28 @@ def deep_copy_model_obj(model_module, model_name, obj_pk, new_obj_pk, user_pk, u
     except ObjectDoesNotExist:
         logger.warning("Object or user no longer exists.")
         return
+
+    o2m_to_preserve = {}
+    fields_to_preserve = set(getattr(model, 'FIELDS_TO_PRESERVE_AT_COPY', []))
+
+    for field in model._meta.get_fields():
+        if field.name in fields_to_preserve:
+            if field.one_to_many:
+                try:
+                    field_val = getattr(obj, field.name)
+                except AttributeError:
+                    continue
+                o2m_to_preserve[field.name] = field_val
+
+    sub_obj_list = []
+    for o2m in o2m_to_preserve:
+        for sub_obj in o2m_to_preserve[o2m].all():
+            sub_model = type(sub_obj)
+            sub_obj_list.append((sub_model.__module__, sub_model.__name__, sub_obj.pk))
+
+    from awx.api.generics import CopyAPIView
+    from awx.main.signals import disable_activity_stream
+
     with transaction.atomic(), ignore_inventory_computed_fields(), disable_activity_stream():
         copy_mapping = {}
         for sub_obj_setup in sub_obj_list: