How to use Terraform v0.13 Beta: Module for_each and count

Terraform
1

Hi Team,

I am still not clear on how to use the feature Terraform v0.13 Beta: Module for_each and count

i specified this

variable “vpc_id” {
type = string
}

variable “subnets” {
type = map(object({
cidr_block = string
availability_zone = string
}))
}

How do i specify the value for cidr_block and availability_zone ?

I tried this

subnets = {
test = {
cidr_block = “10.0.0.0/16”
availability_zone = “eu-west-1”
}
test2= {
cidr_block = “10.10.0.0/16”
availability_zone = “eu-west-1”
}}
it gave me this error Error: Unsupported argument . Any idea how can i fix it ?

2

Hi there,

We recently published Learn tutorials that cover how to use for_each and count in both resources and modules. Both tutorials walks you through an example configuration where you have to implement either for_each or count to manage multiple pieces of infrastructure.

  1. Manage Similar Resources With Count
  2. Manage Similar Resources With For Each

To answer your question, the configuration below would iterate through the subnets variable and create two subnets with differing cidr_block values.

variable "vpc_id" {
  type = string
}

variable "subnets" {
  type = map(object({
    cidr_block        = string
    availability_zone = string
  }))
  default = {
    test = {
      cidr_block        = "10.0.0.0/16"
      availability_zone = "eu-west-1"
    },
    test = {
      cidr_block        = "10.10.0.0/16"
      availability_zone = "eu-west-1"
    }
  }
}

resource "aws_subnet" "main" {
  vpc_id = var.vpc_id

  # Looping through subnet variable
  for_each = var.subnets

  cidr_block        = each.value.cidr_block
  availability_zone = each.value.availability_zone
}

Let me know if that helps or if you have any additional questions!

3

Thank you for the help. It is better situation now

1 Like
4

So i have next issue in the module writing and i will try to explain more .

This is my sample module

module “test1” {
for_each = var.subnets
name = each.value.name
}

and test1 pass the value to a module which pass this to 2 more module name as test1build and test1deploy . And test 1 is invoke by 2 options of subnets

So my questions are

  1. Is the output for test 1 module should it have output also as value = { for p in sort(keys(var.project)) : p => module.elb_http[p].this_elb_dns_name } ?

  2. And i have another module name test2 which need output value from test1 . So how should i declare output and how should be my module test 2 ?

Currently i have test 2 module as module “test2” {
for_each = var.subnets

role_name = module.test1[each.key].role_name
}