Merge list with map in terraform - amazon-web-services

Question

I am writing terraform script to automate the provision of acm for domains, the issue that I am facing is how can I merge the domain and subject_alternative_names like it should pick first domain from domain_name and merge it with first block in subject_alternative_name and go on.
Variable.tf
variable "domain_name" {
description = "Configuration for alb settings"
default = [
"domain.com",
"helloworld.com",
"helloworld2.com",
]
}
variable "subject_alternative_names" {
description = "subject_alternative_names"
default = [ {
domain.com = {
"domain.com",
"domain2.com",
"domain3.com",
},
helloworld.com = {
"helloworld1.com",
"helloworld2.com"
},
hiworld.com = {
"hiworld1.com",
"hiworld2.com"
}
}]
}
variable "region" {
description = "name of the region"
default = "us-east-1"
}
variable "validation_method" {
description = "name of the region"
default = "DNS"
}
variable "tags" {
description = "name of the region"
default = "Test"
}
working variable.tf
variable "domain_name" {
description = "Configuration for alb settings"
default = [
"domain.com",
"helloworld.com",
"helloworld2.com",
"helloworld1.com",
"helloworld3.com",
]
}
variable "subject_alternative_names"{
description = "subject_alternative_names"
default = [
"domain.com",
"helloworld.com",
"helloworld2.com",
"helloworld1.com",
"helloworld3.com",
]
}
variable "region" {
description = "name of the region"
default = "us-east-1"
}
variable "validation_method" {
description = "name of the region"
default = "DNS"
}
variable "tags" {
description = "name of the region"
default = "Test"
}
main.tf
module "acm" {
count = length(var.domain_name)
source = "./modules/acm"
domain_name = var.domain_name[count.index]
validation_method = var.validation_method
tags = var.tags
subject_alternative_names = var.subject_alternative_names
}
resource.tf
variable "domain_name" {
default = ""
description = "Nmae of the domain"
}
variable "validation_method" {
default = ""
description = "Validation method DNS or EMAIL"
}
variable "tags" {
default = ""
description = "tags for the ACM certificate"
}
variable "subject_alternative_names" {
default = ""
description = "subject_alternative_names"
}
resource "aws_acm_certificate" "acm_cert" {
domain_name = var.domain_name
validation_method = var.validation_method
subject_alternative_names = var.subject_alternative_names
lifecycle {
create_before_destroy = true
}
tags = {
Name = var.tags
}
}

Answer 1

The easiest way would be to use a single map:
variable "domain_name_with_alternate_names" {
default = {
"domain.com" = [
"domain.com",
"domain2.com",
"domain3.com",
],
"helloworld.com" = [
"helloworld1.com",
"helloworld2.com"
],
"hiworld.com" = [
"hiworld1.com",
"hiworld2.com"
],
"hiwodd4.com" = []
}
}
module "acm" {
for_each = var.domain_name_with_alternate_names
source = "./modules/acm"
domain_name = each.key
validation_method = var.validation_method
tags = var.tags
subject_alternative_names = each.value
}