Accessing a list inside a list of maps in terraform-CodePudding

I am trying to access a list inside a list of maps in terraform. The structure is as below:

dynamic.tfvars
--------------

nacl=[
    {
        "vpc_name" = "vpc1"
        "acl_name" = "acl1"
        "subnet_name" = ["sub1-az1","sub2-az2"]
    },
    {
        "vpc_name" = "vpc2"
        "acl_name" = "acl2"
        "subnet_name" = ["sub1-az1","sub2-az2"]
    }
]

I am trying to get "subnet_name"(a list) from the list of maps in my child module and it does not work. Below is the piece of code that i am using.

main.tf
-------
data "aws_vpc" "vpc_nacl" {
  count = length(var.nacl[*])
  filter {
    name = "tag:Name"
    values = [element(var.nacl[*]["vpc_name"],count.index)]
  }
}

locals {
  lcl_vpc_nacl = data.aws_vpc.vpc_nacl.*.id
}

data "aws_subnet_ids" "example" {
  count = length(var.nacl[*]["subnet_name"])
  vpc_id = element(local.lcl_vpc_nacl,count.index)
  filter {
    name   = "tag:Name"
    values = [element(var.nacl[*]["subnet_name"],count.index)]
  }
}

I am getting the below error when terraform plan is executed.

│ Error: Incorrect attribute value type
│
│   on Modules\NACL\Main.tf line 28, in data "aws_subnet_ids" "example":
│   28:     values = [element(var.nacl[*]["subnet_name"],count.index)]
│     ├────────────────
│     │ count.index is 1
│     │ var.nacl is list of object with 5 elements
│
│ Inappropriate value for attribute "values": element 0: string required.

Any fixes or suggestions would be highly appreciated. Thanks in advance.

CodePudding user response：

From aws_subnet_ids data source documentation, I see values within filter expects a set.

Looking code you are almost there, but you are passing a list of lists to values which is why you have this error.

element((var.nacl[*]["subnet_name"]), count.index) extracts list of subnets in the format of list.

All you need is to convert into set and pass without square braces like below..

main.tf
-------

data "aws_subnet_ids" "example" {
  count = length(var.nacl[*]["subnet_name"])
  vpc_id = element(local.lcl_vpc_nacl,count.index)
  filter {
    name   = "tag:Name"
    values = toset(element((var.nacl[*]["subnet_name"]), count.index))
  }
}

Give a try & let me know if this helps..