Terrform dyamic block with for_each not working with empty list

Question

I'm trying to extend a module that wraps AWS Secrets Manager. Currently it doesn't support replication and I'm trying to add it. I'm using terraform 0.14.

Here's the variable I've added:

variable "replica_regions" {
  type        = list(string)
  description = "A List of Regions"
  default     = []
}

And here's what I've added inside the "aws_secretsmanager_secret" resource:

  dynamic "replica" {
    for_each = var.replica_regions
    content {
      region = replica.value
    }
  }

This appears to work in that when I add regions it starts to replicate the secret to those regions. And when I remove regions from the list it stops replicating them there. The only issue is when I try to go from 1 region to zero regions, it doesn't seem to do anything and the secret is still be replicated. This happens when I remove replica_regions from the invocation and when I explicitly set it to [].

Any thoughts on why this is?

Answer 1

It is a bug of terraform-provider-aws. If the bug is fixed, it is expected that secret replication will be deleted when variable is in [] state.

This issue should be resolved.