data "aws_iam_policy_document" "dlm_assume" {
  statement {
    effect  = "Allow"
    actions = ["sts:AssumeRole"]

    principals {
      type        = "Service"
      identifiers = ["dlm.amazonaws.com"]
    }
  }
}

resource "aws_iam_role" "dlm" {
  name                 = "apm-wo-analysis-grafana-dlm"
  path                 = "/tf-managed/"
  description          = "DLM snapshot role for the Grafana instance volume"
  assume_role_policy   = data.aws_iam_policy_document.dlm_assume.json
  permissions_boundary = aws_iam_policy.exec_boundary.arn
}

data "aws_iam_policy_document" "dlm" {
  # checkov:skip=CKV_AWS_111: DLM CreateSnapshot/Describe* require Resource=*. Role is boundary-attached and limited to the tagged Grafana volume.
  statement {
    sid    = "DlmSnapshots"
    effect = "Allow"
    actions = [
      "ec2:CreateSnapshot",
      "ec2:CreateSnapshots",
      "ec2:DeleteSnapshot",
      "ec2:DescribeInstances",
      "ec2:DescribeVolumes",
      "ec2:DescribeSnapshots",
      "ec2:DescribeTags",
      "ec2:CreateTags",
      "ec2:DeleteTags",
    ]
    resources = ["*"]
  }

  statement {
    sid    = "DlmKms"
    effect = "Allow"
    actions = [
      "kms:CreateGrant",
      "kms:DescribeKey",
      "kms:GenerateDataKeyWithoutPlaintext",
      "kms:ReEncryptFrom",
      "kms:ReEncryptTo",
      "kms:ListGrants",
    ]
    resources = [
      "arn:aws:kms:${var.aws_region}:${local.account_id}:key/*",
    ]
  }
}

resource "aws_iam_role_policy" "dlm" {
  name   = "grafana-dlm-snapshots"
  role   = aws_iam_role.dlm.id
  policy = data.aws_iam_policy_document.dlm.json
}

resource "aws_dlm_lifecycle_policy" "grafana" {
  description        = "Daily snapshot of the apm-wo grafana volume"
  execution_role_arn = aws_iam_role.dlm.arn
  state              = "ENABLED"

  policy_details {
    resource_types = ["INSTANCE"]

    target_tags = {
      (local.grafana_backup_tag) = "true"
    }

    schedule {
      name = "daily"

      create_rule {
        interval      = 24
        interval_unit = "HOURS"
        times         = ["07:00"]
      }

      retain_rule {
        count = 7
      }
    }
  }
}