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RDS DB clusters should be configured for multiple Availability Zones

This control checks whether high availability is enabled for your RDS DB clusters. RDS DB clusters should be configured for multiple Availability Zones to ensure availability of the data that is stored.

How to fix

Attribute availability_zones of aws_rds_cluster must be non-empty.

Implementation options

Choose the option that matches how you manage Terraform. All options satisfy this control.

Use the compliance.tf registry module to get this control enforced by default. This control is mapped to the frameworks shown in the tabs above. To begin, see get started with compliance.tf.

module "rds_aurora" {
  source  = "nistcsfv11.compliance.tf/terraform-aws-modules/rds-aurora/aws"
  version = ">=10.0.0,<11.0.0"

  engine         = "aurora-postgresql"
  engine_version = "16.1"
  instances = {
    one = {
      instance_class = "db.r6g.large"
    }
  }
  master_username = "root"
  name            = "abc123"
  subnets         = []
  vpc_id          = ""
}

module "rds_aurora" {
  source  = "nistcsf.compliance.tf/terraform-aws-modules/rds-aurora/aws"
  version = ">=10.0.0,<11.0.0"

  engine         = "aurora-postgresql"
  engine_version = "16.1"
  instances = {
    one = {
      instance_class = "db.r6g.large"
    }
  }
  master_username = "root"
  name            = "abc123"
  subnets         = []
  vpc_id          = ""
}

Option 2: Open source module (terraform-aws-modules)

If you use terraform-aws-modules/rds-aurora/aws, configure the required module inputs to satisfy this control. You can later migrate to the compliance.tf module with minimal changes because it is compatible by design.

module "rds_aurora" {
  source  = "terraform-aws-modules/rds-aurora/aws"
  version = ">=10.0.0,<11.0.0"

  engine         = "aurora-postgresql"
  engine_version = "16.1"
  instances = {
    one = {
      instance_class = "db.r6g.large"
    }
  }
  master_username = "root"
  name            = "abc123"
  subnets         = []
  vpc_id          = ""
}

Option 3: Terraform AWS provider resources

If you manage resources directly, configure the relevant Terraform AWS provider resources to meet this control. See docs for the resources involved: aws_rds_cluster.

resource "aws_rds_cluster" "this" {
  backtrack_window                = 72
  cluster_identifier              = "pofix-example-cluster"
  enabled_cloudwatch_logs_exports = ["audit", "postgresql"]
  engine                          = "aurora-mysql"
  master_password                 = "ChangeMe123!"
  master_username                 = "dbadmin"
}
Which option should I choose?
  • Compliance.tf module (recommended): controls enforced by default and mapped to frameworks.
  • Open source module (terraform-aws-modules): compatible by design with compliance.tf. Same variable names for an easy, low-change migration path when you are ready.
  • Terraform AWS provider resources: manage Terraform resources directly.

Tool mappings

Use these identifiers to cross-reference this control across tools, reports, and evidence.

  • Compliance.tf (CTF) Control: rds_db_cluster_multiple_az_enabled

  • Powerpipe Controls: aws_compliance.control.cis_v500_2_2_4, aws_compliance.control.cis_v600_3_2_4, aws_compliance.control.rds_db_cluster_multiple_az_enabled