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The db_instance_automated_backups_replication submodule enables cross-region replication of automated backups for an RDS DB instance. It creates an aws_db_instance_automated_backups_replication resource in the destination region that continuously replicates backups from the source region. This is distinct from a cross-region read replica: automated backups replication does not create a live standby instance — it copies backup data to the destination region so that you can restore a DB instance there in a disaster recovery scenario.

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Source

./modules/db_instance_automated_backups_replication

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Usage

This submodule must be deployed in the destination region by configuring an alternate AWS provider:
main.tf
provider "aws" {
  alias  = "primary"
  region = "eu-west-1"
}

provider "aws" {
  alias  = "replica"
  region = "eu-central-1"
}

module "db" {
  source = "terraform-aws-modules/rds/aws"

  providers = {
    aws = aws.primary
  }

  identifier = "my-db"

  engine         = "postgres"
  engine_version = "17"
  # ...

  # Backups are required for replication
  backup_retention_period = 1
}

module "db_automated_backups_replication" {
  source = "terraform-aws-modules/rds/aws//modules/db_instance_automated_backups_replication"

  # Run in the destination region
  providers = {
    aws = aws.replica
  }

  source_db_instance_arn = module.db.db_instance_arn
  kms_key_arn            = aws_kms_key.replica_region.arn
  retention_period       = 14
}
The source RDS instance must have backup_retention_period set to 1 or greater. Automated backups replication cannot be enabled on an instance with backups disabled.

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Input variables

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source_db_instance_arn
string
The ARN of the source DB instance whose automated backups will be replicated to this region.Default: null
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kms_key_arn
string
The ARN of the KMS encryption key in the destination AWS region used to encrypt the replicated backups. If not specified, the default AWS-managed KMS key for RDS is used.Default: null
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retention_period
number
The number of days to retain the replicated automated backups in the destination region. Must be between 1 and 35.Default: 7
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pre_signed_url
string
A pre-signed URL containing a Signature Version 4 signed request for the StartDBInstanceAutomatedBackupsReplication action in the source region. Required only when replicating to a region that requires an explicit pre-signed URL.Default: null
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create
bool
Whether to create the automated backups replication resource. Set to false to skip creation.Default: true
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region
string
Region where this resource will be managed. Defaults to the region set in the provider configuration.Default: null

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Complete example

The examples/complete-postgres/ and examples/cross-region-replica-postgres/ examples show this submodule used alongside a KMS module:
main.tf
data "aws_caller_identity" "current" {}

module "kms" {
  source  = "terraform-aws-modules/kms/aws"
  version = "~> 1.0"

  description = "KMS key for cross region automated backups replication"

  aliases                 = ["my-cross-region-rds"]
  aliases_use_name_prefix = true
  key_owners              = [data.aws_caller_identity.current.arn]

  providers = {
    aws = aws.replica_region
  }
}

module "db_automated_backups_replication" {
  source = "terraform-aws-modules/rds/aws//modules/db_instance_automated_backups_replication"

  source_db_instance_arn = module.db.db_instance_arn
  kms_key_arn            = module.kms.key_arn

  providers = {
    aws = aws.replica_region
  }
}

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Relationship to cross-region read replicas

FeatureAutomated Backups ReplicationCross-Region Read Replica
What it createsBackup copies in another regionA live RDS instance in another region
SourceAny RDS instance with backups enabledAn RDS instance
CostStorage cost for backup dataFull instance + storage cost
RestoreMust manually restore from backupCan promote replica to primary
Use caseDisaster recovery (RPO)Read scaling + DR (lower RTO)
See the read replicas guide for documentation on cross-region live replicas.

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