Task: Create a Terraform script for an AWS EKS node group (with name attribute set to "example") linked to a specific EKS cluster (with name attribute set to "example"). Define a resource with details including the node group name, node role ARN, and subnet IDs. Configure scaling parameters (desired size is 1, max size is 2, and min size is 1, with max unavailable set to 1) and update settings for node management. Include dependencies on IAM role policy attachments to ensure proper permissions management during lifecycle events of EC2 instances and network interfaces (in particular, make sure the EKS worker node policy, the EKS CNI policy, and the EC2 container registry read only policy are attached).

Specification:
has one "aws_eks_node_group" resource
with one "cluster_name"
with one "node_group_name"
with one "node_role_arn"
with one "subnet_ids"
with one "scaling_config" containing:
one "desired_size"
one "max_size"
one "min_size"
with one "update_config" containing:
one "max_unavailable"
with dependencies on three IAM role policy attachments

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"
}

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"
  map_public_ip_on_launch = true

  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"
  map_public_ip_on_launch = true

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

resource "aws_internet_gateway" "main" {
  vpc_id = aws_vpc.main.id
}

resource "aws_route_table" "main" {
  vpc_id = aws_vpc.main.id

  route {
    cidr_block = "0.0.0.0/0"
    gateway_id = aws_internet_gateway.main.id
  }
}

resource "aws_route_table_association" "first" {
  subnet_id      = aws_subnet.test_eks_1.id
  route_table_id = aws_route_table.main.id
}

resource "aws_route_table_association" "second" {
  subnet_id      = aws_subnet.test_eks_2.id
  route_table_id = aws_route_table.main.id
}

resource "aws_security_group" "first" {
  name        = "test-security-group"
  description = "Allow traffic for Elasticsearch"
  vpc_id      = aws_vpc.main.id
}

resource "aws_vpc_security_group_ingress_rule" "ingress1" {
  security_group_id = aws_security_group.first.id
  cidr_ipv4 = "0.0.0.0/0"
  ip_protocol = "-1"
}

resource "aws_vpc_security_group_egress_rule" "egress1" {
  security_group_id = aws_security_group.first.id
  cidr_ipv4         = "0.0.0.0/0"
  ip_protocol       = "-1"
}

resource "aws_iam_role" "example-cluster" {
  name = "eks-cluster-role"

  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-cluster.name
}

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

resource "aws_eks_cluster" "example" {
  name     = "example"
  role_arn = aws_iam_role.example-cluster.arn

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

resource "aws_iam_role" "example-group" {
  name = "eks-cluster-group-role"

  assume_role_policy = <<POLICY
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": ["eks.amazonaws.com", "ec2.amazonaws.com"]
      },
      "Action": "sts:AssumeRole"
    }
  ]
}
POLICY
}

resource "aws_iam_role_policy_attachment" "example-AmazonEKSWorkerNodePolicy" {
  policy_arn = "arn:aws:iam::aws:policy/AmazonEKSWorkerNodePolicy"
  role       = aws_iam_role.example-group.name
}

resource "aws_iam_role_policy_attachment" "example-AmazonEKS_CNI_Policy" {
  policy_arn = "arn:aws:iam::aws:policy/AmazonEKS_CNI_Policy"
  role       = aws_iam_role.example-group.name
}

resource "aws_iam_role_policy_attachment" "example-AmazonEC2ContainerRegistryReadOnly" {
  policy_arn = "arn:aws:iam::aws:policy/AmazonEC2ContainerRegistryReadOnly"
  role       = aws_iam_role.example-group.name
}

resource "aws_eks_node_group" "example" {
  cluster_name    = aws_eks_cluster.example.name
  node_group_name = "example"
  node_role_arn   = aws_iam_role.example-group.arn
  subnet_ids      = [ aws_subnet.test_eks_1.id, aws_subnet.test_eks_2.id ]

  scaling_config {
    desired_size = 1
    max_size     = 2
    min_size     = 1
  }

  update_config {
    max_unavailable = 1
  }

  # Ensure that IAM Role permissions are created before and deleted after EKS Node Group handling.
  # Otherwise, EKS will not be able to properly delete EC2 Instances and Elastic Network Interfaces.
  depends_on = [
    aws_iam_role_policy_attachment.example-AmazonEKSWorkerNodePolicy,
    aws_iam_role_policy_attachment.example-AmazonEKS_CNI_Policy,
    aws_iam_role_policy_attachment.example-AmazonEC2ContainerRegistryReadOnly,
  ]
}



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

default has_aws_eks_node_group_example = false

has_aws_eks_node_group_example {
    node_group := input.planned_values.root_module.resources[_]
    node_group.type == "aws_eks_node_group"
    node_group.values.cluster_name == input.planned_values.root_module.resources[_].values.name
    node_group.values.node_group_name == "example"
    node_group.values.scaling_config[_].desired_size == 1
    node_group.values.scaling_config[_].max_size == 2
    node_group.values.scaling_config[_].min_size == 1
    node_group.values.update_config[_].max_unavailable == 1

    node_group2 := input.configuration.root_module.resources[_]
    node_group2.expressions.node_role_arn.references != null
    node_group2.expressions.subnet_ids != null

    count(node_group2.depends_on) == 3
    # Checking for AmazonEKSWorkerNodePolicy:
    worker_policy := input.configuration.root_module.resources[_]
    contains(node_group2.depends_on[_], worker_policy.name)
    contains(worker_policy.expressions.policy_arn.constant_value, "AmazonEKSWorkerNodePolicy")

    # Checking for AmazonEKS_CNI_Policy:
    worker_policy2 := input.configuration.root_module.resources[_]
    contains(node_group2.depends_on[_], worker_policy2.name)
    contains(worker_policy2.expressions.policy_arn.constant_value, "AmazonEKS_CNI_Policy")

    # Checking for AmazonEC2ContainerRegistryReadOnly:
    worker_policy3 := input.configuration.root_module.resources[_]
    contains(node_group2.depends_on[_], worker_policy3.name)
    contains(worker_policy3.expressions.policy_arn.constant_value, "AmazonEC2ContainerRegistryReadOnly")
}