aws_msk_cluster provisioned_throughput block has multiple issues

[ryan-dyer-sp]

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Terraform CLI and Terraform AWS Provider Version

Terraform v1.1.4 on linux_amd64

• provider registry.terraform.io/hashicorp/aws v4.23.0

Affected Resource(s)

• aws_msk_cluster

Terraform Configuration Files

resource "aws_msk_cluster" "cluster" {
...
    storage_info {
      ebs_storage_info {
        volume_size = var.ebs_volume_size
        dynamic "provisioned_throughput" {
          for_each = var.ebs_volume_throughput == "0" ? [] : ["enabled"]
          content {
            enabled           = true
            volume_throughput = var.ebs_volume_throughput
          }
        }
        dynamic "provisioned_throughput" {
          for_each = var.ebs_volume_throughput != "0" ? [] : ["disabled"]
          content {
            enabled = false
          }
        }
      }
    }
  }
}

Actual Behavior

The existing behavior seems to only support two configurations.

• Not having throughput enabled in AWS and not having the provisioned_throughput block in code
• enabling/enabled throughput with provisioned_throughput block

Attempts to disable provisioned throughput require that the block no longer contain the volume_throughput field; thus the weird double dynamic blocks in example above.

Once disabled terraform plan constantly detects a chance in the plan as the p_t block doesnt appear to exist as part of the state. How simple removal of the block is not sufficient to disable p_t in the case that is already enabled on the cluster.

Steps to Reproduce

1. Create MSK with provisioning enabled
2. attempt to disable provisioning by simply setting enabled to false and leaving volume_throughput field as is. This fails as volume_throughput cannot be set when setting enabled to false. This is detected at apply time, not at plan time.
3. Attempt to disable provisioning by removing the block entirely. Plan and apply "succeed" however no changes are actually made to the cluster. It is simply removed from state and subsequent plans continue to show a change is needed.
4. Disable provisioning by setting enabled = false and no volume_throughput. This succeeds though subsequent terraform plans will show that the p_t block still needs to be added and set to enabled=false.

Important Factoids

References