Terraform Version

Terraform v1.4.2
on darwin_arm64
+ provider registry.terraform.io/hashicorp/aws v4.67.0

Your version of Terraform is out of date! The latest version
is 1.11.3. You can update by downloading from https://www.terraform.io/downloads.html

Affected Pages

• https://developer.hashicorp.com/terraform/language/meta-arguments/count
• https://developer.hashicorp.com/terraform/language/meta-arguments/for_each
• https://developer.hashicorp.com/terraform/language/meta-arguments/lifecycle

What is the docs issue?

The behavior of create_before_destroy on a resource collection type using count or for_each isn't clear from documentation. There are two ways it could be interpreted to behave:

1. Every resource in the collection is an individual resource and create_before_destroy is applied to each separately. If a plan wants to both add and delete resources with separate for_each keys or count indices from the collection, the creates and destroys happen in an undefined order.
2. create_before_destroy applies to the collection as a whole. If a plan wants to both add and delete resources with separate for_each keys or count indices from the collection, all resources to add will be created before any resources to remove are destroyed.

We had a brief production outage because we assumed the latter, but we think we observed the former. The docs do not make it clear which behavior to expect.

Proposal

Explicitly document how create_before_destroy and maybe lifecycle arguments in general are applied to resources in a collection and whether any of them apply to the collection as a whole.

References

No response