Terraform 'for each' 循环遍历作为字符串列表的元素，不适用

Question

I'm about to create a route table and associate them to subnets, so I've 3 subnets (list of strings) they're already created, but when I'm trying to associate a route table to subnets, it's associating only with 1st one, and I guess same issues while I'm trying to associate a NAT gateway which is also a list of strings .

Here is outputs:

  + nat_list = [
      + "nat-0980ffedd5471b76d",
      + "nat-053701e207f6e92b2",
      + "nat-0be06d45baf164edc",
    ]

  + subnets  = [
      + "subnet-04c920f8908d7e502",
      + "subnet-0e9e9333180cab627",
      + "subnet-0caae55b544e4b63d",
    ]

Here is my main.tf

resource "aws_route_table" "public" {
   count  = length(local.azs)
   vpc_id = aws_vpc.vpc[0].id
   tags   = var.tags
} <<< Creating without any problems



resource "aws_route" "public_ipv4"  {
   for_each       = { for route in local.public_ipv4 : route.name => route}
   route_table_id = aws_route_table.public.*.id
   
   ...  ...
   
   nat_gateway_id         = ??? lookup(each.value, "nat", "" ) Not working ???
   destination_cidr_block = lookup(each.value, "destination_cidr_block", "" )
   
   ...  ...
}



resource "aws_route_table_association" "public"  {
   count          = length(local.azs)
   subnet_id      = lookup(var.parameters[count.index], "public_subnet", [])
   route_table_id = aws_route_table.public.*.id
}



variable "parameters"                {
   description = "The route table parameters"   
   type        = list(object({
     ... ...
     public_subnet = list(string)
     ... ...
   }))
   default     = []
}

Update: Local var

locals {
    public_ipv4 = {[
        {
           name = "NAT(s) to MyLogSys ${local.counter + 1 }"
           nat = aws_nat_gateway.translate.*.id 
           destination_cidr_block = "100.0.20.0/20"
        }
    ]}
}

I made a research, however it seems there is no similar issue

Answer 1

Based on a chat discussion.

It was suggested to replace:

for_each       = { for route in local.public_ipv4 : route.name => route}

with

for_each       = { for idx, route in local.public_ipv4 : idx => route}

where idx will take values 0,1,2,... based on the size of local.public_ipv4 .

To protect from accessing elements in the lists which have fewer elements than local.public_ipv4 , element can be used.