Terraform looping on complex object type

Question

I am trying to create a aws_route through terraform .. I have an object which I need to parse and create resources based on all possible combinations .. can someone suggest me how I can do it.?

My var is as below

Test_route = {

Route_table_id_1 = {
Destination = [“10.0.0.0”,”10.1.0.0”]
Nat_id = [“abd”,”sky”]
}
Route_table_id_2 = {
Destination = [“10.0.0.0”,”10.1.0.0”,”0.0.0.0/0”]
Nat_id = [“abd”,”sky”]
}

}

I need to loop in a way as depicted below

    resource "aws_route" "private_subnet_route_to_nat_gw" {
         
      route_table_id         = "Route_table_id_1 "
      destination_cidr_block = “10.0.0.0”
      nat_gateway_id         = "abc"
    
      route_table_id         = "Route_table_id_1 "
      destination_cidr_block = ”10.1.0.0”
      nat_gateway_id         = "abc"

route_table_id         = "Route_table_id_1 "
      destination_cidr_block = “10.0.0.0”
      nat_gateway_id         = "sky"
route_table_id         = "Route_table_id_1 "
      destination_cidr_block = ”10.1.0.0”
      nat_gateway_id         = "sky"
route_table_id         = "Route_table_id_2 "
      destination_cidr_block = ”10.1.0.0”
      nat_gateway_id         = "abc"
route_table_id         = "Route_table_id_2 "
      destination_cidr_block = ”10.1.0.0”
      nat_gateway_id         = "sky"
route_table_id         = "Route_table_id_2 "
      destination_cidr_block = ”10.0.0.0”
      nat_gateway_id         = "abc"
route_table_id         = "Route_table_id_2 "
      destination_cidr_block = ”10.0.0.0”
      nat_gateway_id         = "sky"
route_table_id         = "Route_table_id_2 "
      destination_cidr_block = ”0.0.0.0/0”
      nat_gateway_id         = "abc"
route_table_id         = "Route_table_id_2 "
      destination_cidr_block = ”0.0.0.0/0”
      nat_gateway_id         = "sky"
    }

I tried with for loops and for_each but was failing in looping through all the possible scenarios

Answer 1

You have to flatten your variable:

locals {
    flat_Test_route = merge(flatten([
      for rt_id, rt_details in var.Test_route:[
          for destination in rt_details.Destination: {
            for nat_id in rt_details.Nat_id:  
              "${rt_id}-${destination}-${nat_id}" => {
                "rt_id" = rt_id  
                "destination" = destination
                "nat_id" = nat_id
              }
          }
      ]                                        
    ])...) # do NOT remove the dots
}

then

resource "aws_route" "private_subnet_route_to_nat_gw" {

      for_each = local.flat_Test_route 
         
      route_table_id         = each.value.rt_id
      destination_cidr_block = each.value.destination
      nat_gateway_id         = each.value.nat_id
}