Workaround for `count.index` in Terraform Module - module

Question

I need a workaround for using count.index inside a module block for some input variables. I have a habit of over-complicating problems, so maybe there's a much easier solution.
File/Folder Structure:
modules/
main.tf
ignition/
main.tf
modules/
files/
main.tf
template_files/
main.tf
End Goal: Create an Ignition file for each instance I'm deploying. Each Ignition file has instance-specific info like hostname, IP address, etc.
All of this code works if I use a static value or a variable without cound.index. I need help coming up with a workaround for the address, gateway, and hostname variables specifically. If I need to process the count.index inside one of the child modules, that's totally fine. I can't seem to wrap my brain around that though. I've tried null_data_source and null_resource blocks from the child modules to achieve that, but so far no luck.
Variables:
workers = {
Lab1 = {
"lab1k8sc8r001" = "192.168.17.100/24"
}
Lab2 = {
"lab2k8sc8r001" = "192.168.18.100/24"
}
}
gateway = {
Lab1 = [
"192.168.17.1",
]
Lab2 = [
"192.168.18.1",
]
}
From modules/main.tf, I'm calling the ignition module:
module "ignition_workers" {
source = "./modules/ignition"
virtual_machines = var.workers[terraform.workspace]
ssh_public_keys = var.ssh_public_keys
files = [
"files_90-disable-auto-updates.yaml",
"files_90-disable-console-logs.yaml",
]
template_files = {
"files_eth0.nmconnection.yaml" = {
interface-name = "eth0",
address = element(values(var.workers[terraform.workspace]), count.index),
gateway = element(var.gateway, count.index % length(var.gateway)),
dns = join(";", var.dns_servers),
dns-search = var.domain,
}
"files_etc_hostname.yaml" = {
hostname = element(keys(var.workers[terraform.workspace]), count.index),
}
"files_chronyd.yaml" = {
ntp_server = var.ntp_server,
}
}
}
From modules/ignition/main.tf I take the files and template_files variables to build the Ignition config:
module "ingition_file_snippets" {
source = "./modules/files"
files = var.files
}
module "ingition_template_file_snippets" {
source = "./modules/template_files"
template_files = var.template_files
}
data "ct_config" "fedora-coreos-config" {
count = length(var.virtual_machines)
content = templatefile("${path.module}/assets/files_ssh_authorized_keys.yaml", {
ssh_public_keys = var.ssh_public_keys
})
pretty_print = true
snippets = setunion(values(module.ingition_file_snippets.files), values(module.ingition_template_file_snippets.files))
}

Answer 1

I am not quite sure what you are trying to achieve so I can not give any detailed examples.
But modules in terraform do not support count or for_each yet. So you can also not use count.index.
You might want to change your module to take lists/maps of input and create those lists/maps via for-expressions by transforming them from some input variables.
You can combine for with if to create a filtered subset of your source list/map. Like in:
[for s in var.list : upper(s) if s != ""]
I hope this helps you work around the missing count support.