How do I import existing resources into a nested stack whose parent is the root stack in CloudFormation?

Last updated: 2022-05-20

I have a nested stack in AWS CloudFormation whose parent stack is a root stack. I want to import an existing resource into the nested stack. But when I try to import the resource in the root stack, I get the error “This template does not include any resources to import.”

Short description

When the nested stack's parent stack is the root, it's a best practice to modify only the root stack.

Note: The following resolution is for importing a resource into a nested stack whose parent stack is the root stack.

Important: Always run drift detection on stacks after an import operation to verify that the imported resource isn't drifted.

Resolution

To import resources into a nested stack, follow these steps:

  1. Update the root template with a Retain DeletionPolicy on the nested AWS::CloudFormation::Stack resource to detach the stack from the root stack without deleting it.
  2. Update the root stack by removing AWS::CloudFormation::Stack from the template.
    Note: After you update the root stack, the nested stack is still marked as Nested.
  3. Perform an import operation on the detached nested stack to import the existing resource.
    Note: Because the stack is still considered Nested, a warning appears that recommends you to update the root stack instead. Ignore it and continue to update the nested stack. Don't modify any other resources during the import.
  4. Move the detached nested stack out of IMPORT_COMPLETE status by updating it again with an easily removable change, such as adding outputs or tags.
  5. Perform an import operation on the root stack to add the nested stack back into its nested hierarchy.
    Note: Make sure that the root template includes a reference for the nested stack's updated template so that it contains the newly imported resource.

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