Trying to use terraform to create multiple EC2 instances with separate route 53 records - amazon-ec2

Question

So I have a project where I'm trying to do something simple like create a reusable project that could create the following:
EC2 SG - 1 per workload
EC2 instances - could be 1 or more
Route 53 records - 1 per EC2 instance created
This project works just fine without any issues with using just 1 instance, but when I increase the count to anything besides 1, I get the following:
Error: Invalid index
│
│ on .terraform/modules/ec2_servers_dns_name/main.tf line 18, in resource "aws_route53_record" "this":
│ 18: records = split(",", var.records[count.index])
│ ├────────────────
│ │ count.index is 1
│ │ var.records is list of string with 1 element
│
│ The given key does not identify an element in this collection value: the
│ given index is greater than or equal to the length of the collection.
In my core main.tf, the modules for EC2 and Route53 look like below:
# EC2 Instances
module "ec2_servers" {
ami = data.aws_ami.server.id
associate_public_ip_address = var.ec2_associate_public_ip_address
disable_api_termination = var.ec2_disable_api_termination
ebs_optimized = var.ec2_ebs_optimized
instance_count = var.ec2_servers_instance_count
instance_dns_names = var.ec2_servers_dns_name_for_tags
instance_type = var.ec2_servers_instance_type
key_name = var.ec2_key_name
monitoring = var.ec2_enhanced_monitoring
name = format("ec2-%s-%s-server",local.tags["application"],local.tags["environment"])
rbd_encrypted = var.ec2_rbd_encrypted
rbd_volume_size = var.ec2_rbd_volume_size
rbd_volume_type = var.ec2_rbd_volume_type
subnet_id = concat(data.terraform_remote_state.current-vpc.outputs.app_private_subnets)
user_data = var.ec2_user_data
vpc_security_group_ids = [module.ec2_security_group_servers.this_security_group_id, var.baseline_sg]
tags = local.tags
}
# Create DNS entry for EC2 Instances
module "ec2_servers_dns_name" {
domain = var.domain_name
instance_count = var.ec2_servers_instance_count
name = var.ec2_servers_dns_name
private_zone = "true"
records = module.ec2_servers.private_ip
ttl = var.ttl
type = var.record_type
providers = {
aws = aws.network
}
}
And the resources (EC2/Route53) in our core module repo are shown below:
EC2
locals {
is_t_instance_type = replace(var.instance_type, "/^t[23]{1}\\..*$/", "1") == "1" ? "1" : "0"
}
resource "aws_instance" "this" {
count = var.instance_count
ami = var.ami
associate_public_ip_address = var.associate_public_ip_address
credit_specification {
cpu_credits = local.is_t_instance_type ? var.cpu_credits : null
}
disable_api_termination = var.disable_api_termination
ebs_optimized = var.ebs_optimized
iam_instance_profile = var.iam_instance_profile
instance_initiated_shutdown_behavior = var.instance_initiated_shutdown_behavior
instance_type = var.instance_type
ipv6_addresses = var.ipv6_addresses
ipv6_address_count = var.ipv6_address_count
key_name = var.key_name
lifecycle {
ignore_changes = [private_ip, root_block_device, ebs_block_device, volume_tags, user_data, ami]
}
monitoring = var.monitoring
placement_group = var.placement_group
private_ip = var.private_ip
root_block_device {
encrypted = var.rbd_encrypted
volume_size = var.rbd_volume_size
volume_type = var.rbd_volume_type
}
secondary_private_ips = var.secondary_private_ips
source_dest_check = var.source_dest_check
subnet_id = element(var.subnet_id, count.index)
tags = merge(tomap({"Name"= var.name}), var.tags, var.instance_dns_names[count.index])
tenancy = var.tenancy
user_data = var.user_data[count.index]
volume_tags = var.volume_tags
vpc_security_group_ids = var.vpc_security_group_ids
}
Route53
data "aws_route53_zone" "this" {
name = var.domain
private_zone = var.private_zone
}
terraform {
required_providers {
aws = {
source = "hashicorp/aws"
version = ">= 2.7.0"
}
}
}
resource "aws_route53_record" "this" {
count = var.instance_count
name = var.name[count.index]
records = split(",", var.records[count.index])
type = var.type
ttl = var.ttl
zone_id = data.aws_route53_zone.this.zone_id
}
It seems like it's possibly with the output for the private IP for EC2, but I'm not sure. Here's the output for the private IP for the EC2 resource
output "private_ip" {
description = "The private IP address assigned to the instance."
value = [aws_instance.this[0].private_ip]
}
And the records variable in the R53 resource is set to a list.
Any thoughts on how to pull the private IP for the EC2 instances (whether it's one or multiple) have the output for each private IP be called dynamically in the R53 module so the R53 record can be created without issue?

Answer 1

Try
output "private_ip" {
description = "The private IP address assigned to the instance."
value = [aws_instance.this[*].private_ip]
}
The 0 returns only one element
EDIT: Add this
tostring()