iam_cluster_autoscaler.tf

data "aws_iam_policy_document" "cluster_autoscaler_role" {
  statement {
    actions = ["sts:AssumeRoleWithWebIdentity"]
    effect  = "Allow"

    condition {
      test     = "StringEquals"
      variable = "${replace(aws_iam_openid_connect_provider.eks.url, "https://", "")}:sub"
      values = [
        "system:serviceaccount:kube-system:cluster-autoscaler",
        "system:serviceaccount:kube-system:aws-cluster-autoscaler"
      ]
    }

    principals {
      identifiers = [aws_iam_openid_connect_provider.eks.arn]
      type        = "Federated"
    }
  }
}

resource "aws_iam_role" "cluster_autoscaler_role" {
  count              = var.cluster_autoscaler_toggle ? 1 : 0
  assume_role_policy = data.aws_iam_policy_document.cluster_autoscaler_role.json
  name               = format("%s-cluster-autoscaler", var.cluster_name)
}

data "aws_iam_policy_document" "cluster_autoscaler_policy" {
  version = "2012-10-17"

  statement {

    effect = "Allow"
    actions = [
      "autoscaling-plans:DescribeScalingPlans",
      "autoscaling-plans:GetScalingPlanResourceForecastData",
      "autoscaling-plans:DescribeScalingPlanResources",
      "autoscaling:DescribeAutoScalingNotificationTypes",
      "autoscaling:DescribeLifecycleHookTypes",
      "autoscaling:DescribeAutoScalingInstances",
      "autoscaling:DescribeTerminationPolicyTypes",
      "autoscaling:DescribeScalingProcessTypes",
      "autoscaling:DescribePolicies",
      "autoscaling:DescribeTags",
      "autoscaling:DescribeLaunchConfigurations",
      "autoscaling:DescribeMetricCollectionTypes",
      "autoscaling:DescribeLoadBalancers",
      "autoscaling:DescribeLifecycleHooks",
      "autoscaling:DescribeAdjustmentTypes",
      "autoscaling:DescribeScalingActivities",
      "autoscaling:DescribeAutoScalingGroups",
      "autoscaling:DescribeAccountLimits",
      "autoscaling:DescribeScheduledActions",
      "autoscaling:DescribeLoadBalancerTargetGroups",
      "autoscaling:DescribeNotificationConfigurations",
      "autoscaling:DescribeInstanceRefreshes",
      "autoscaling:SetDesiredCapacity",
      "autoscaling:TerminateInstanceInAutoScalingGroup",
      "ec2:DescribeLaunchTemplateVersions"
    ]

    resources = [
      "*"
    ]

  }
}

resource "aws_iam_policy" "cluster_autoscaler_policy" {
  count       = var.cluster_autoscaler_toggle ? 1 : 0
  name        = format("%s-cluster-autoscaler", var.cluster_name)
  path        = "/"
  description = var.cluster_name

  policy = data.aws_iam_policy_document.cluster_autoscaler_policy[count.index].json
}

resource "aws_iam_policy_attachment" "cluster_autoscaler" {
  count = var.cluster_autoscaler_toggle ? 1 : 0
  name  = "cluster_autoscaler"
  roles = [
    aws_iam_role.cluster_autoscaler_role[count.index].name
  ]

  policy_arn = aws_iam_policy.cluster_autoscaler_policy[count.index].arn
}