Task: Define a variable 'cluster_name' of type string. Create an AWS EKS cluster named based on the provided cluster name variable, associating it with an IAM role. Configure the EKS cluster with VPC subnet IDs for networking. Ensure that IAM role permissions are handled before and after EKS cluster management for proper resource handling. Use local-exec provisioners to manage kubectl configuration during cluster creation and destruction. Define an IAM role with a policy attachment for Amazon EKS cluster and service policies.

Specification:
has one "aws_eks_cluster" resource
with one "name"
with one "role_arn"
with one "subnet_ids" in "vpc_config"
with multiple "depends_on" dependencies
with multiple "local-exec" provisioners 
with a "command"
with a "when" 

has one "aws_iam_role" resource
with one "name"
with one "assume_role_policy"

has one "aws_iam_role_policy_attachment" resource for "eks_cluster_policy"
with one "policy_arn"
with one "role"

has one "aws_iam_role_policy_attachment" resource for "eks_service_policy"
with one "policy_arn"
with one "role"

Terraform configuration (main.tf):
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = ">= 5.75"
    }
  }

  required_version = ">= 1.9.0"
}

provider "aws" {
  region = "us-east-1"
}

variable "cluster_name" {
  type = string
  default = "test-cluster"
}

data "aws_region" "current" {}

resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
}

data "aws_availability_zones" "available" {
  state = "available"
}

resource "aws_subnet" "test_eks_1" {
  vpc_id     = aws_vpc.main.id
  cidr_block = "10.0.1.0/24"

  availability_zone = data.aws_availability_zones.available.names[0]
}

resource "aws_subnet" "test_eks_2" {
  vpc_id     = aws_vpc.main.id
  cidr_block = "10.0.2.0/24"

  availability_zone = data.aws_availability_zones.available.names[1]
}

resource "aws_iam_role" "example" {
  name = "${var.cluster_name}-eks"

  assume_role_policy = jsonencode({
    Statement = [{
      Action = "sts:AssumeRole"
      Effect = "Allow"
      Principal = {
        Service = "eks.amazonaws.com"
      }
    }]
    Version = "2012-10-17"
  })
}

resource "aws_iam_role_policy_attachment" "eks_cluster_policy" {
  policy_arn = "arn:aws:iam::aws:policy/AmazonEKSClusterPolicy"
  role       = aws_iam_role.example.name
}

resource "aws_iam_role_policy_attachment" "eks_service_policy" {
  policy_arn = "arn:aws:iam::aws:policy/AmazonEKSServicePolicy"
  role       = aws_iam_role.example.name
}

resource "aws_eks_cluster" "example" {
  name     = var.cluster_name
  role_arn = aws_iam_role.example.arn

  vpc_config {
    subnet_ids = [ aws_subnet.test_eks_1.id, aws_subnet.test_eks_2.id ]
  }

  # Ensure that IAM Role permissions are created before and deleted after EKS Cluster handling.
  # Otherwise, EKS will not be able to properly delete EKS managed EC2 infrastructure such as Security Groups.
  depends_on = [
    aws_iam_role_policy_attachment.eks_cluster_policy,
    aws_iam_role_policy_attachment.eks_service_policy,
  ]

  # Manage kubectl configuration
  provisioner "local-exec" {
    command = "aws eks --region ${data.aws_region.current.name} update-kubeconfig --name ${self.name}"
  }

  provisioner "local-exec" {
    when    = destroy
    command = "kubectl config unset users.${self.arn}"
  }
  provisioner "local-exec" {
    when    = destroy
    command = "kubectl config unset clusters.${self.arn}"
  }
  provisioner "local-exec" {
    when    = destroy
    command = "kubectl config unset contexts.${self.arn}"
  }
}


Validation policy (checks.rego):
package terraform.validation

default has_aws_eks_cluster = false
default has_aws_iam_role = false
default has_aws_iam_role_policy_attachment_eks_cluster = false
default has_aws_iam_role_policy_attachment_eks_service = false

has_aws_eks_cluster {
    some i
    eks_cluster := input.configuration.root_module.resources[i]
    eks_cluster.type == "aws_eks_cluster"
    eks_cluster.expressions.name != null
    eks_cluster.expressions.role_arn != null
    eks_cluster.expressions.vpc_config[_].subnet_ids != null
    count(eks_cluster.expressions.vpc_config[_].subnet_ids) > 0
    count(eks_cluster.depends_on) > 0
    has_local_exec_provisioners(eks_cluster)
}


has_local_exec_provisioners(resource) {
    resource.provisioners != null
    local_exec_count := [provisioner | 
        provisioner := resource.provisioners[_]; 
        provisioner.type == "local-exec"
    ]
    count(local_exec_count) > 0
    has_local_exec_command(local_exec_count)
}


has_local_exec_command(provisioners) {
    some i
    provisioners[i].expressions.command != null
}

has_aws_iam_role {
    some i
    iam_role := input.planned_values.root_module.resources[i]
    iam_role.type == "aws_iam_role"
    iam_role.values.name != null
    iam_role.values.assume_role_policy != null
}


has_aws_iam_role_policy_attachment_eks_cluster {
    some i
    policy_attachment := input.planned_values.root_module.resources[i]
    policy_attachment.type == "aws_iam_role_policy_attachment"
    policy_attachment.values.policy_arn == "arn:aws:iam::aws:policy/AmazonEKSClusterPolicy"
}


has_aws_iam_role_policy_attachment_eks_service {
    some i
    policy_attachment := input.planned_values.root_module.resources[i]
    policy_attachment.type == "aws_iam_role_policy_attachment"
    policy_attachment.values.policy_arn == "arn:aws:iam::aws:policy/AmazonEKSServicePolicy"
}

valid_configuration {
    has_aws_eks_cluster
    has_aws_iam_role
    has_aws_iam_role_policy_attachment_eks_cluster
    has_aws_iam_role_policy_attachment_eks_service
}