how Implement sms_configuration in terraform as optional?

Question

I'm adding sms_configuration to my cognito module but... I still want to use null values... because there are times when a project is not going to use this attribute, it necessarily asks me to give them a value, is it required?

resource "aws_cognito_user_pool" "user_pools" {
  for_each = var.user_pools
  name    = each.value.name    
  .... other atributes....

  sms_configuration {
    external_id    = ""
    sns_caller_arn = ""
    sns_region     = ""
  }
}

After apply:

module.aws_user_pool[0].aws_cognito_user_pool.user_pools["analityc"]: Creating... ╷ │ Error: creating Cognito User Pool: InvalidParameter: 1 validation error(s) found. │ - missing required field, CreateUserPoolInput.SmsConfiguration.SnsCallerArn.

The idea was to use it only when sending values, in the tfvars... but in any case it requests that a value must be put in external_id and in sns_caller_arn.

If I don't use the block, if it does the apply correctly.

Answer 1

What you could do is use dynamic in combination with for_each meta-argument. For example:

resource "aws_cognito_user_pool" "user_pools" {
  for_each = var.user_pools
  name    = each.value.name    
  .... other atributes....

  dynamic "sms_configuration" {
    for_each = var.sms_configuration_enabled ? [1] : []
    content {
      external_id    = ""
      sns_caller_arn = ""
      sns_region     = ""
    }
  }
  .
  .
  .
}

You would then have to define the sms_configuration_enabled variable (type bool) and decide how to define other parameters required by the sms_configuration block.