Terraform_module_for_each_depends_on

# Attach the public ELBs to the instance if they change
resource "aws_elb_attachment" "default" {
  depends_on              = [var.elb_depends_on]

  for_each                = toset(local.instance_ids)
  
  elb                     = aws_elb.default.id
  instance                = each.value
}

  63:   for_each                = toset(local.instance_ids)

The "for_each" value depends on resource attributes that cannot be determined
until apply, so Terraform cannot predict how many instances will be created.
To work around this, use the -target argument to first apply only the
resources that the for_each depends on.```