[Terraform] for_each

- terraform에서 비슷한 resource를 여러개 생성하는 경우 필요함

- for_each 로 선택할 수 있는 자료구조: set, map

resource "azurerm_resource_group" "rg" { 
  for_each = {
    a_group = "eastus"
    another_group = "westus2"
  }
  name     = each.key
  location = each.value
} // map

// 위의 resource를 변수로 활용할 경우
// azurerm_resource_group.rg["a_group"], azurerm_resource_group.rg["another_group"]

resource "aws_iam_user" "the-accounts" { 
  for_each = toset( ["Todd", "James", "Alice", "Dottie"] )
  name     = each.key
} // set

 

In child module

# my_buckets.tf
module "bucket" {
  for_each = toset(["assets", "media"])
  source   = "./publish_bucket"
  name     = "${each.key}_bucket"
}

# publish_bucket/bucket-and-cloudfront.tf
variable "name" {} # this is the input parameter of the module

resource "aws_s3_bucket" "example" {
  # Because var.name includes each.key in the calling
  # module block, its value will be different for
  # each instance of this module.
  bucket = var.name

  # ...
}

resource "aws_iam_user" "deploy_user" {
  # ...
}

 

응용

variable "vpcs" {
  type = map(object({
    cidr_block = string
  }))
}

resource "aws_vpc" "example" { // vpcs 변수에 따라 여러개의 vpc 생성
  # One VPC for each element of var.vpcs
  for_each = var.vpcs

  # each.value here is a value from var.vpcs
  cidr_block = each.value.cidr_block
}

resource "aws_internet_gateway" "example" { // vpc에 따라 1:1로 igw 생성
  # One Internet Gateway per VPC
  for_each = aws_vpc.example

  # each.value here is a full aws_vpc object
  vpc_id = each.value.id
}

output "vpc_ids" {
  value = {
    for k, v in aws_vpc.example : k => v.id
  }

  # The VPCs aren't fully functional until their
  # internet gateways are running.
  depends_on = [aws_internet_gateway.example]
}

locals {
  subnet_ids = toset([
    "subnet-abcdef",
    "subnet-012345",
  ])
}

resource "aws_instance" "server" {
  for_each = local.subnet_ids

  ami           = "ami-a1b2c3d4"
  instance_type = "t2.micro"
  subnet_id     = each.key # each.key와 each.value set에서 같음

  tags = {
    Name = "Server ${each.key}"
  }
}

 

 

출처

https://www.terraform.io/language/meta-arguments/for_each