Error: "UPDATE_FAILED resources.scaling: Resource CREATE failed" during scale out operation failure

Products

• VMware Integrated OpenStack
• VMware Telco Cloud Platform

Issue/Introduction

• Scale in and scale out operations in VIO using Heat stack do not complete successfully. 
• The command openstack stack resource list <STACK_ID> output shows that the stack contains a stale instance that was deleted.

Environment

VIO 7.3

TCP 3.0

Cause

• Deleting an instance directly from the OpenStack creates an inconsistency between the Nova database and the Heat stack as it leaves stale entries within the Heat orchestration layer.
• This orphaned resource actively prevents subsequent scale-in and scale-out operations from completing successfully.

Resolution

1. Identify the orphaned resource references still exist in the Heat orchestration layer:
   
   openstack stack resource list <STACK_ID> --nested-depth 5

2. Review the stack parameters to identify the specific stale scale-out parameter (e.g., number_of_scaled_out_PLs showing as '1' despite the instance being deleted):
   
   openstack stack show <STACK_ID> -c parameters

3. Backup the live stack parameter state before making any modifications:
   
   openstack stack show <STACK_ID> -c parameters -f json > prod_stack_parameters_backup.json

4. Backup the core stack template infrastructure:
   
   openstack stack template show <STACK_ID> > prod_stack_template_backup.yaml

5. Execute a targeted scale-down update using the parameter identified in step 2 to force Heat to drop the orphaned resource references and synchronize its state:
   
   openstack stack update --existing --parameter number_of_scaled_out_PLs=0 <STACK_ID>

6. Monitor the stack event list to confirm the deletion event is processing:
   
   openstack stack event list <STACK_ID>

7. Verify the stack status transitions successfully to UPDATE_COMPLETE:
   
   openstack stack show <STACK_ID> -c stack_status

8. Verify the orphaned resources have been properly removed from the stack:
   
   openstack stack resource list <STACK_ID> --nested-depth 5

Additional Information

If the scale down operation fails due to Flavor mismatch error refer to the KB Error: "Error validating value 'flavor name ####': No Flavor matching {'name' 'flavor name ####'}. (HTTP 404)" while updating a Heat stack.