> ## Documentation Index
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> Use this file to discover all available pages before exploring further.

# db_subnet_group submodule

> Reference for the db_subnet_group submodule, which provisions an aws_db_subnet_group resource.

The `db_subnet_group` submodule creates an `aws_db_subnet_group` that spans a list of VPC subnets. DB instances must be associated with a subnet group to run within a VPC.

## Source

```
./modules/db_subnet_group
```

## Usage

Use this submodule standalone when you want to manage a subnet group separately from a DB instance, or share it across multiple instances:

```hcl theme={null}
module "db_subnet_group" {
  source  = "terraform-aws-modules/rds/aws//modules/db_subnet_group"
  version = "~> 7.0"

  name            = "my-db-subnet-group"
  use_name_prefix = false
  description     = "Subnet group for production databases"
  subnet_ids      = ["subnet-0abc123", "subnet-0def456", "subnet-0ghi789"]

  tags = {
    Environment = "production"
    Team        = "platform"
  }
}
```

Then reference the output in a DB instance:

```hcl theme={null}
module "db" {
  source  = "terraform-aws-modules/rds/aws"
  version = "~> 7.0"

  identifier             = "mydb"
  create_db_subnet_group = false
  db_subnet_group_name   = module.db_subnet_group.db_subnet_group_id

  # ... other variables
}
```

## Input variables

<ParamField path="create" type="bool">
  Whether to create the subnet group resource. Set to `false` to skip all resource creation.

  Default: `true`
</ParamField>

<ParamField path="name" type="string">
  The name of the DB subnet group. When `use_name_prefix` is `true`, this is used as a prefix.

  Default: `""`
</ParamField>

<ParamField path="use_name_prefix" type="bool">
  Determines whether to use `name` as-is or create a unique name beginning with `name` as the prefix.

  Default: `true`
</ParamField>

<ParamField path="description" type="string">
  The description of the DB subnet group.

  Default: `null`
</ParamField>

<ParamField path="subnet_ids" type="list(string)">
  A list of VPC subnet IDs for the subnet group. At least two subnets in separate Availability Zones are recommended for high availability.

  Default: `[]`
</ParamField>

<ParamField path="region" type="string">
  Region where the subnet group will be managed. Defaults to the region set in the provider configuration.

  Default: `null`
</ParamField>

<ParamField path="tags" type="map(string)">
  A mapping of tags to assign to the DB subnet group resource.

  Default: `{}`
</ParamField>

## Outputs

<ResponseField name="db_subnet_group_id" type="string">
  The name (ID) of the DB subnet group. Pass this to the `db_subnet_group_name` input of a DB instance.
</ResponseField>

<ResponseField name="db_subnet_group_arn" type="string">
  The ARN of the DB subnet group.
</ResponseField>