Terraform Module with Count Can't Have Duplicate Elements - digital-ocean

Question

Tricky one to explain in a title, or even form a question around it, so I'll start with some code (simplified for, err, simplicity):
resource "digitalocean_domain" "this_domain" {
name = "${var.domain}"
ip_address = "${var.main_ip}"
}
resource "digitalocean_record" "this_a_record" {
count = "${length(var.a_records)}"
domain = "${var.domain}"
type = "A"
name = "${element(keys(var.a_records), count.index)}"
value = "${lookup(var.a_records, element(keys(var.a_records), count.index))}"
}
Given the above being part of a module called dns, I can call it like this:
module "example_com_dns" {
source = "./modules/dns"
domain = "example.com"
main_ip = "1.2.3.4"
a_records = {
"#" = "5.6.7.8"
"self" = "9.10.11.12"
"www" = "5.6.7.8"
}
}
Running this works as expected. I get the A records I expect; #, self, www, all pointing to the correct IPs.
However, it can't handle duplicate names. For example, putting in multiple # records results in only one of them being written, I'm guessing because each iteration for the name simply overwrites the previous # record.
Is there a way to have multiple duplicate names? i.e. In the example above, have something like:
....
"#" = "5.6.7.8"
"#" = "20.21.22.23"
"#" = "30.31.32.33"
"self" = "9.10.11.12"
"www" = 5.6.7.8"
...

Answer 1

In that case instead of using keys to get map keys you should put the A records into a list like:
a_records = [
["#" , "5.6.7.8"],
["#" , "7.6.7.8"],
["#" , "9.9.9.9"],
["self", "7.10.11.12"],
["self", "11.11.111.11"],
["self", "12.12.12.12"],
["self", "13.13.13.13"],
["www" , "14.14.14.14"]
]
and assign name and value as
name = "${element(var.a_records[count.index],0)}"
value = "${element(var.a_records[count.index],1)}"
and you will get all the duplicate A records that you want
The following is a simple working example of how to do it. You can cut and paste the code into a functional terraform session and it will run without errors and create duplicate A records.
You will need to extend the example to fit your needs of external modules, etc.
variable "a_records" { default = [
["#" , "5.6.7.8"],
["#" , "7.6.7.8"],
["#" , "9.9.9.9"],
["self", "7.10.11.12"],
["self", "11.11.111.11"],
["self", "12.12.12.12"],
["self", "13.13.13.13"],
["www" , "14.14.14.14"],
["www" , "14.14.14.14"]
]
}
variable domain { default = "example20180731.com" }
variable main_ip { default = "1.1.1.1" }
resource "digitalocean_domain" "this_domain" {
name = "${var.domain}"
ip_address = "${var.main_ip}"
}
resource "digitalocean_record" "this_a_record" {
depends_on = ["digitalocean_domain.this_domain"]
count = "${length(var.a_records)}"
domain = "${var.domain}"
type = "A"
name = "${element(var.a_records[count.index],0)}"
value = "${element(var.a_records[count.index],1)}"
}
This is another example. It shows how to do it using external data supplied through a module. It's also code which can be copied and pasted into a functional terraform session and will work, as is.
create-dup-A-records.tf
module "dns" {
source = "./modules/dns"
}
variable domain { default = "example20180731.com" }
variable main_ip { default = "1.1.1.1" }
resource "digitalocean_domain" "this_domain" {
name = "${var.domain}"
ip_address = "${var.main_ip}"
}
resource "digitalocean_record" "this_a_record" {
depends_on = ["digitalocean_domain.this_domain"]
count = "${length(module.dns.a_records_in_dns_module)}"
domain = "${var.domain}"
type = "A"
name = "${element(module.dns.a_records_in_dns_module[count.index],0)}"
value = "${element(module.dns.a_records_in_dns_module[count.index],1)}"
}
./modules/dns/dns.tf
variable "a_records" { default = [
["#" , "5.6.7.8"],
["#" , "7.6.7.8"],
["#" , "9.9.9.9"],
["self", "7.10.11.12"],
["self", "11.11.111.11"],
["self", "12.12.12.12"],
["self", "13.13.13.13"],
["www" , "14.14.14.14"],
["www" , "14.14.14.14"]
]
}
output "a_records_in_dns_module" {
value = "${var.a_records}"
}

Answer 2

Turns out it's a limitation of Terraform:
https://github.com/hashicorp/terraform/issues/18573#event-1765829698
#don is mostly there in his answer, but you can't have that work with passed in variables. You need to use the split hack to pass it is as a string, then make it a list, as described in the above linked issue:
Call from main.tf:
module "example_com_dns" {
source = "./modules/dns"
domain = "example.com"
main_ip = "${lookup(var.example_com_dns, "at01")}"
a_records = [
"# 5.6.7.8",
"# 7.6.7.8",
]
}
dns.tf module:
resource "digitalocean_record" "this_a_record" {
depends_on = ["digitalocean_domain.this_domain"]
count = "${length(var.a_records)}"
domain = "${var.domain}"
type = "A"
name = "${element(split(" ", var.a_records[count.index]),0)}"
value = "${element(split(" ", var.a_records[count.index]),1)}"
}
For whoever else is trying to do this from a Google search; my advice is don't. 0.12 will be out soon, and will fix all these kinds of insanity.