AWS RDS Aurora Terraform module

Upstream version 10.4.1
4 controls from FedRAMP Low Baseline Rev 4 requirements

Terraform Module Source

fedramplow.compliance.tf/terraform-aws-modules/rds-aurora/aws
ComplianceInputsOutputsResourcesRulesDiff (3)README

AWS RDS Aurora Terraform module

Terraform module which creates AWS RDS Aurora resources.

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Available Features

  • Autoscaling of read-replicas
  • Global cluster
  • Enhanced monitoring
  • Serverless cluster (v1 and v2)
  • Import from S3
  • Fine grained control of individual cluster instances
  • Custom endpoints
  • RDS multi-AZ support (not Aurora)
  • Aurora Limitless
  • Aurora DSQL cluster

Usage

module "cluster" {
  source  = "terraform-aws-modules/rds-aurora/aws"

  name           = "test-aurora-db-postgres96"
  engine         = "aurora-postgresql"
  engine_version = "17.5"

  cluster_instance_class = "db.r8g.large"
  instances = {
    one = {}
    two = {
      instance_class = "db.r8g.2xlarge"
    }
  }

  vpc_id               = "vpc-12345678"
  db_subnet_group_name = "db-subnet-group"
  security_group_ingress_rules = {
    ex1_ingress = {
      cidr_ipv4 = "10.20.0.0/20"
    }
    ex1_ingress = {
      referenced_security_group_id = "sg-12345678"
    }
  }

  storage_encrypted   = true
  apply_immediately   = true
  monitoring_interval = 10

  enabled_cloudwatch_logs_exports = ["postgresql"]

  tags = {
    Environment = "dev"
    Terraform   = "true"
  }
}

Cluster Instance Configuration

There are a couple different configuration methods that can be used to create instances within the cluster:

[!NOTE] Only the pertinent attributes are shown for brevity

  1. Create homogenous cluster of any number of instances
  • Resources created:
    • Writer: 1
    • Reader(s): 2
  cluster_instance_class = "db.r8g.large"
  instances = {
    one   = {}
    two   = {}
    three = {}
  }
  1. Create homogenous cluster of instances w/ autoscaling enabled. This is redundant and we'll show why in the next example.
  • Resources created:
    • Writer: 1
    • Reader(s):
      • At least 4 readers (2 created directly, 2 created by appautoscaling)
      • At most 7 reader instances (2 created directly, 5 created by appautoscaling)

[!NOTE] Autoscaling uses the instance class specified by cluster_instance_class.

  cluster_instance_class = "db.r8g.large"
  instances = {
    one   = {}
    two   = {}
    three = {}
  }

  autoscaling_enabled      = true
  autoscaling_min_capacity = 2
  autoscaling_max_capacity = 5
  1. Create homogeneous cluster scaled via autoscaling. At least one instance (writer) is required
  • Resources created:
    • Writer: 1
    • Reader(s):
      • At least 1 reader
      • At most 5 readers
  cluster_instance_class = "db.r8g.large"
  instances = {
    one = {}
  }

  autoscaling_enabled      = true
  autoscaling_min_capacity = 1
  autoscaling_max_capacity = 5

  1. Create heterogenous cluster to support mixed-use workloads

    It is common in this configuration to independently control the instance promotion_tier paired with endpoints to create custom endpoints directed at select instances or instance groups.

  • Resources created:
    • Writer: 1
    • Readers: 2
  cluster_instance_class = "db.r8g.large"
  instances = {
    one = {
      instance_class      = "db.r8g.2xlarge"
      publicly_accessible = true
    }
    two = {
      identifier     = "static-member-1"
      instance_class = "db.r8g.2xlarge"
    }
    three = {
      identifier     = "excluded-member-1"
      instance_class = "db.r8g.large"
      promotion_tier = 15
    }
  }
  1. Create heterogenous cluster to support mixed-use workloads w/ autoscaling enabled
  • Resources created:
    • Writer: 1
    • Reader(s):
      • At least 3 readers (2 created directly, 1 created through appautoscaling)
      • At most 7 readers (2 created directly, 5 created through appautoscaling)

[!NOTE] Autoscaling uses the instance class specified by cluster_instance_class.

  cluster_instance_class = "db.r8g.large"
  instances = {
    one = {
      instance_class      = "db.r8g.2xlarge"
      publicly_accessible = true
    }
    two = {
      identifier     = "static-member-1"
      instance_class = "db.r8g.2xlarge"
    }
    three = {
      identifier     = "excluded-member-1"
      instance_class = "db.r8g.large"
      promotion_tier = 15
    }
  }

  autoscaling_enabled      = true
  autoscaling_min_capacity = 1
  autoscaling_max_capacity = 5

Conditional Creation

The following values are provided to toggle on/off creation of the associated resources as desired:

# This RDS cluster will not be created
module "cluster" {
  source  = "terraform-aws-modules/rds-aurora/aws"

  # Disable creation of cluster and all resources
  create = false

  # Disable creation of subnet group - provide a subnet group
  create_db_subnet_group = false

  # Disable creation of security group - provide a security group
  create_security_group = false

  # Disable creation of monitoring IAM role - provide a role ARN
  create_monitoring_role = false

  # ... omitted
}

Known limitations (Terraform/OpenTofu, not this module)

A few requests come up again and again and cannot be implemented by this module, or by any module: Terraform requires lifecycle arguments to be literal values inside the resource block. hashicorp/terraform#18367 has been open since 2018, #22544 since 2019, and opentofu/opentofu#1329 is the same request for OpenTofu.

  • terraform destroy deleted an Aurora cluster - Native option: set deletion_protection = true and keep a final snapshot configured, both of which this module already exposes.

Compliance.tf serves this module with these rules applied at download time, on top of whatever your organization already has enabled there. Inputs and outputs do not change; the source line does. Drop the version argument and pin the release you use by adding &version= and that release number to the URL. To get started, register a free compliance.tf account and configure an access token:

source = "https://registry.compliance.tf/terraform-aws-modules/rds-aurora/aws?add_rules=lifecycle_prevent_destroy_data"

The full workaround for each item above, and the exact diff each rule makes, are in the compliance.tf docs for this module. To preview a diff without an account, open this module in the Rules Playground.

Disclosure: written by this module's maintainer, who also builds compliance.tf.

Examples

  • Autoscaling: A PostgreSQL cluster with enhanced monitoring and autoscaling enabled
  • DSQL: Multi region and single region DSQL clusters
  • Global Cluster: A PostgreSQL global cluster with clusters provisioned in two different region
  • Limitless: A PostgreSQL Limitless cluster
  • Multi-AZ: A multi-AZ RDS cluster (not using Aurora engine)
  • MySQL: A simple MySQL cluster
  • PostgreSQL: A simple PostgreSQL cluster
  • S3 Import: A MySQL cluster created from a Percona Xtrabackup stored in S3
  • Serverless: Serverless V1 and V2 (PostgreSQL and MySQL)

Documentation

Terraform documentation is generated automatically using pre-commit hooks. Follow installation instructions here.

Authors

Module is maintained by Anton Babenko with help from these awesome contributors.

License

Apache 2 Licensed. See LICENSE for full details.

Additional information for users from Russia and Belarus