Strange behaviour with lists (I think?)

[johnhamelink]

Hey guys,

Forward

I was struggling with an issue I was having with piping a list through a module and then looping through it with the count attribute in a resource definition. I spoke to some people on #terraform-tool on freenode, and managed to find a workaround for this issue, but to me it seems like a bug that this code doesn't work the obvious way.

Objective

I was attempting to take the output of aws_route53_zone's name_servers list, and add a nameserver record for each via cloudflare.

I came up with this: https://gist.github.com/johnhamelink/b4d315e3cad437fc1865

This code would fail on the point of trying to set the records with:

Error applying plan:

4 error(s) occurred:

* cloudflare_record.new_record.0: Failed to update CloudFlare Record: API Error: You entered '<strong>${element(split(&quot;,&quot;, module.app.route53_nameservers), count.index)}</strong>' which is not a valid authoritative host name.
* cloudflare_record.new_record.1: Failed to update CloudFlare Record: API Error: You entered '<strong>${element(split(&quot;,&quot;, module.app.route53_nameservers), count.index)}</strong>' which is not a valid authoritative host name.
* cloudflare_record.new_record.3: Failed to update CloudFlare Record: API Error: You entered '<strong>${element(split(&quot;,&quot;, module.app.route53_nameservers), count.index)}</strong>' which is not a valid authoritative host name.
* cloudflare_record.new_record.2: Failed to update CloudFlare Record: API Error: You entered '<strong>${element(split(&quot;,&quot;, module.app.route53_nameservers), count.index)}</strong>' which is not a valid authoritative host name.

Terraform does not automatically rollback in the face of errors.
Instead, your Terraform state file has been partially updated with
any resources that successfully completed. Please address the error
above and apply again to incrementally change your infrastructure.

Workaround

After playing around a bit, I found that I could make terraform work correctly simply by joining the list by hand:

output "route53_nameservers" {
  value = "${aws_route53_zone.production_api.name_servers.0},${aws_route53_zone.production_api.name_servers.1},${aws_route53_zone.production_api.name_servers.2},${aws_route53_zone.production_api.name_servers.3}"
}

terraform.tfstate

The terraform.tfstate file includes the output from the aws_zone:

                "aws_route53_zone.production_api": {
                    "type": "aws_route53_zone",
                    "primary": {
                        "id": "DUMMY",
                        "attributes": {
                            "comment": "Managed by Terraform",
                            "id": "DUMMY",
                            "name": "api.exmaple.com",
                            "name_servers.#": "4",
                            "name_servers.0": "ns-9999.awsdns-11.org",
                            "name_servers.1": "ns-9998.awsdns-11.co.uk",
                            "name_servers.2": "ns-9997.awsdns-11.com",
                            "name_servers.3": "ns-9996.awsdns-11.net",
                            "tags.#": "0",
                            "zone_id": "DUMMY"
                        }
                    }
                }

Considering the format of the terraform.tfstate file, to me it seems like a bug that the join function seemingly cannot join together the nameservers.

[radeksimko]

I believe this bug has been already fixed in #2157 and merged, just not released yet.

You can either try and build from master or wait for the next release.

[johnhamelink]

Thank you, I will wait for the next release.

[phinze]

Fixed and merged and released in the past! 😀

[ghost]

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