RHINENG-12954 retrieve operating_system using get method (#479)

Author: r14chandra

ros/processor/inventory_events_consumer.py

@@ -156,7 +156,7 @@ def process_system_details(self, msg):
                     "fqdn": host['fqdn'],
                     "cloud_provider": host['system_profile']['cloud_provider'],
                     "stale_timestamp": host['stale_timestamp'],
-                    "operating_system": host['system_profile']['operating_system'],
+                    "operating_system": host['system_profile'].get('operating_system'),
                     "groups": host.get('groups', [])
                 }
                 system = update_system_record(db.session, **system_fields)
@@ -188,7 +188,7 @@ def process_system_details(self, msg):
                         "fqdn": host['fqdn'],
                         "cloud_provider": host['system_profile']['cloud_provider'],
                         "stale_timestamp": host['stale_timestamp'],
-                        "operating_system": host['system_profile']['operating_system'],
+                        "operating_system": host['system_profile'].get('operating_system'),
                         "groups": host.get('groups', [])
                     }
                     system = get_or_create(db.session, System, 'inventory_id', **system_fields)