Terraform Route 53 DNS 记录指向 AWS Aurora 读取器实例

Question

I am trying to create Aurora reader instances with terraform as below:

resource "aws_rds_cluster_instance" "wordpress_cluster_instance_readers" {
  count              = var.number_of_instances # 3
  apply_immediately  = true
  cluster_identifier = aws_rds_cluster.wordpress_db_cluster.id
  identifier         = "wordpress-cluster-instance-reader${format(count.index + 1)}"
  instance_class     = "db.t2.small"
  engine             = aws_rds_cluster.wordpress_db_cluster.engine
  engine_version     = aws_rds_cluster.wordpress_db_cluster.engine_version

  depends_on = [aws_rds_cluster.wordpress_db_cluster]
}

for Route53 DNS pointing to Aurora readers I used.

resource "aws_route53_record" "readers" {
  count = var.number_of_instances

  zone_id = var.zone_id
  name    = "reader${count.index + 1}.${var.domain}"
  type    = "CNAME"
  ttl     = "300"
  records = [element(aws_rds_cluster_instance.wordpress_cluster_instance_readers[*], count.index)]
}

I get below error.

│ Error: Incorrect attribute value type
│   on main.tf line 463, in resource "aws_route53_record" "readers":
│  463:   records = [element(aws_rds_cluster_instance.wordpress_cluster_instance_readers[*], count.index)]
│     ├────────────────
│     │ aws_rds_cluster_instance.wordpress_cluster_instance_readers is tuple with 3 elements
│     │ count.index is 1
│ 
│ Inappropriate value for attribute "records": element 0: string required.

How should i fix the records to reflect reader instances.

Answer 1

You should be able to test your terraform code using terraform console, with that you will see the outcome of that [element....] block and understand that you are not retrieving the URL with the string that should be in the records argument Marco pointed out the kind of code that should be in that argument but I would like to add this recommendation about using terraform console. Once in the console, you could test

element(aws_rds_cluster_instance.wordpress_cluster_instance_readers[*], 1)

and see that is kind of the same as

element(aws_rds_cluster_instance.wordpress_cluster_instance_readers, 1)

Which is going to return the whole aws_rds_cluster_instance object and not the value of the element that needs to go in the records argument

Now if you test

aws_rds_cluster_instance.wordpress_cluster_instance_readers[1]

you are going to retrieve the same as with the previous tests not needing the element function and as in Markos sugestion if you add the element from the object that you need to retrieve you will have the string you are aiming for which is probably "endpoint"

aws_rds_cluster_instance.wordpress_cluster_instance_readers[1].endpoint

so in the end the line should be looking something like this:

records = aws_rds_cluster_instance.wordpress_cluster_instance_readers[count.index].endpoint

as suggested by Marko