// main.tf
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 3.27"
    }
  }

  required_version = ">= 0.14.9"
}

provider "aws" {
  profile = "user1"
  region  = "ap-northeast-2"
}

locals {
  serverconfig = [
    for server in var.configuration : [
      for i in range(1, server.no_of_instances + 1) : {
        instance_name = server.application_name == "skpark-login" || server.application_name == "skpark-install" ? "${server.application_name}" : "${server.application_name}${i}"
        instance_type = server.instance_type
        volume_size = server.volume_size
      }
    ]
  ]
}
// We need to Flatten it before using it
locals {
  instances = flatten(local.serverconfig)
}

resource "aws_instance" "infra1" {
  for_each = { for server in local.instances : server.instance_name => server }

  ami                         = "ami-0ded4aeabdfcffac4" // Ubuntu - Deep Learning AMI
  associate_public_ip_address = true
  instance_type               = each.value.instance_type
  key_name                    = "key1"
  security_groups = [
    "sg-XXXX"
  ]
  subnet_id = "subnet-XXXX"
  tags = {
    Name = each.value.instance_name
  }
  root_block_device {
    volume_size = each.value.volume_size
  }
}

// variables.tf
variable "configuration" {
  description = "The total configuration, List of Objects/Dictionary"
  default     = [{}]
}

// terraform.tfvars
configuration = [
  {
    "application_name" : "skpark-login",
    "instance_type" : "i3en.xlarge",
    "no_of_instances" : "1",
    "volume_size": 2000 // 2TB
  },
  {
    "application_name" : "skpark-install",
    "instance_type" : "t3.xlarge",
    "no_of_instances" : "1",
    "volume_size": 200 
  },
  {
    "application_name" : "skpark-gpu-node",
    "instance_type" : "g4dn.xlarge", # GPU(T4 1ea) nodes
    "no_of_instances" : "2"
    "volume_size": 200
  }
]