[Bug]: Constant diff on update or error on creation of aws_ce_cost_category

[ohookins]

Terraform Core Version

1.8.4

AWS Provider Version

5.50.0

Affected Resource(s)

• aws_ce_cost_category

Expected Behavior

A new creation of the resource completes without error, and updates complete without a constant diff.

Actual Behavior

Working around the constant diff prevents the resource being created in the first place. Forming the resource so the resource can be created properly results in a constant diff on re-plan/re-apply.

Relevant Error/Panic Output Snippet

│ Error: updating Cost Explorer Cost Category (arn:aws:ce::xxxx:costcategory/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx): operation error Cost Explorer: UpdateCostCategoryDefinition, https response error StatusCode: 400, RequestID: xxxx, api error ValidationException: Failed to update Cost Category: Invalid INHERITED_VALUE rule defined. Rule and Value attributes must be null
│ 
│   with aws_ce_cost_category.accounts,
│   on ce-cost-category-accounts.tf line 4, in resource "aws_ce_cost_category" "accounts":
│    4: resource "aws_ce_cost_category" "accounts" {

This is the error that we get if we attempt to fix the constant diff, which breaks creation or updating of the resource.

Terraform Configuration Files

resource "aws_ce_cost_category" "accounts" {
  name            = "AccountName"
  rule_version    = "CostCategoryExpression.v1"

  rule {
    type = "INHERITED_VALUE"
    inherited_value {
      dimension_name = "LINKED_ACCOUNT_NAME"
    }
  }
}

This works, but results in a constant diff on re-applies. This suggests an empty rule {} block (within the outer rule block) is required to prevent the constant diff.

  # aws_ce_cost_category.accounts will be updated in-place
  ~ resource "aws_ce_cost_category" "accounts" {
        id              = "arn:aws:ce::xxxx:costcategory/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
        name            = "AccountName"
        tags            = {}
        # (6 unchanged attributes hidden)

      - rule {
          - type  = "INHERITED_VALUE" -> null
            # (1 unchanged attribute hidden)

          - inherited_value {
              - dimension_name = "LINKED_ACCOUNT_NAME" -> null
                # (1 unchanged attribute hidden)
            }

          - rule {
            }
        }
      + rule {
          + type  = "INHERITED_VALUE"
            # (1 unchanged attribute hidden)

          + inherited_value {
              + dimension_name = "LINKED_ACCOUNT_NAME"
                # (1 unchanged attribute hidden)
            }
        }
    }

Indeed, if you supply the empty rule {} block where the diff suggests, this allows a subsequent plan to proceed without any diff for this resource. However, creating the resource anew with the empty rule {} block in place leads to the error as pasted above.

Steps to Reproduce

1. Create a aws_ce_cost_category resource as above, with the empty rule {} block in place.
2. Plan/apply. It will fail to create with the error as mentioned above.
3. Remove the empty rule {} block. The resource will create as expected.
4. Plan/apply, it will show a constant diff on every plan now.

Debug Output

N/A

Panic Output

N/A

Important Factoids

No response

References

No response

Would you like to implement a fix?

None

[github-actions]

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