How to Import an AWS RDS DB Subnet Group into Terraform

Import AWS RDS DB Subnet Group with Terraback (recommended)

Terraback reverse-engineers your live infrastructure: it reads the Amazon RDS resource with read-only credentials, generates the HCL, and produces the exact import block. Two commands take you from a live AWS RDS DB Subnet Group to managed Terraform.

terraback scan all aws --region us-east-1

terraback aws import --method bulk

The Terraform import block

Terraback emits a Terraform 1.5+ import block like the one below. Because the block lives in your configuration, the import is reviewable in a pull request and repeatable across environments.

import {
  to = aws_db_subnet_group.prod
  id = "prod-db-subnets"
}

Example aws_db_subnet_group configuration

Here is a realistic AWS RDS DB Subnet Group block. Terraback generates a fuller version from your actual resource attributes; this is a minimal, valid starting point.

resource "aws_db_subnet_group" "prod" {
  name       = "prod-db-subnets"
  subnet_ids = ["subnet-0bb1c79de3a1b2c3d", "subnet-0cc2d8aef4b2c3d4e"]

  tags = {
    Name = "prod-db-subnets"
  }
}

Gotchas when importing a AWS RDS DB Subnet Group

• Import by the subnet group name, which AWS stores lowercase; using a different case forces replacement.
• The subnets themselves are separate aws_subnet resources and are not imported with the group.
• A subnet group must span at least two Availability Zones, so confirm subnet_ids cover multiple AZs before apply.
• RDS instances and Aurora clusters reference this group by name through db_subnet_group_name.

Doing it manually with terraform import

The native approach is to write the aws_db_subnet_group block by hand, then run terraform import aws_db_subnet_group.example <import-id> for every resource, one at a time. That works for a handful of resources, but it does not scale: you author all the HCL yourself and repeat the command for each item. Terraback generates the HCL and the import blocks for your whole account in one pass.

Import other AWS resources