terraform-aws-modules/terraform-aws-transit-gateway

Terraform module to create AWS Transit Gateway resources 🇺🇦

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Aug 6, 2026

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registry.terraform.io/modules/terraform-aws-modules/transit-gateway/aws

aws

aws-vpc

terraform-module

transit-gateway

README

AWS Transit Gateway Terraform module

Terraform module which creates Transit Gateway resources on AWS.

Usage with VPC module

module "tgw" {
  source  = "terraform-aws-modules/transit-gateway/aws"

  name        = "my-tgw"
  description = "My TGW shared with several other AWS accounts"

  enable_auto_accept_shared_attachments = true

  vpc_attachments = {
    vpc = {
      vpc_id       = "vpc-1234556abcdef"
      subnet_ids   = ["subnet-abcde012", "subnet-bcde012a", "subnet-fghi345a"]
      dns_support  = true
      ipv6_support = true

      tgw_routes = [
        {
          destination_cidr_block = "30.0.0.0/16"
        },
        {
          blackhole              = true
          destination_cidr_block = "40.0.0.0/20"
        }
      ]
    }
  }

  ram_allow_external_principals = true
  ram_principals                = [307990089504]

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

Examples

Complete example shows TGW in combination with the VPC module and Resource Access Manager (RAM).
Multi-account example shows TGW resources shared with different AWS accounts (via Resource Access Manager (RAM)).

Requirements

Name	Version
terraform	>= 1.5.7
aws	>= 6.28

Providers

Name	Version
aws	>= 6.28

Modules

No modules.

Resources

Name	Type
aws_ec2_tag.this	resource
aws_ec2_transit_gateway.this	resource
aws_ec2_transit_gateway_route.this	resource
aws_ec2_transit_gateway_route_table.this	resource
aws_ec2_transit_gateway_route_table_association.this	resource
aws_ec2_transit_gateway_route_table_propagation.this	resource
aws_ec2_transit_gateway_vpc_attachment.this	resource
aws_ram_principal_association.this	resource
aws_ram_resource_association.this	resource
aws_ram_resource_share.this	resource
aws_ram_resource_share_accepter.this	resource
aws_route.this	resource

Inputs

Name	Description	Type	Default	Required
amazon_side_asn	The Autonomous System Number (ASN) for the Amazon side of the gateway. By default the TGW is created with the current default Amazon ASN.	`string`	`null`	no
create_tgw	Controls if TGW should be created (it affects almost all resources)	`bool`	`true`	no
create_tgw_routes	Controls if TGW Route Table / Routes should be created	`bool`	`true`	no
description	Description of the EC2 Transit Gateway	`string`	`null`	no
enable_auto_accept_shared_attachments	Whether resource attachment requests are automatically accepted	`bool`	`false`	no
enable_default_route_table_association	Whether resource attachments are automatically associated with the default association route table	`bool`	`true`	no
enable_default_route_table_propagation	Whether resource attachments automatically propagate routes to the default propagation route table	`bool`	`true`	no
enable_dns_support	Should be true to enable DNS support in the TGW	`bool`	`true`	no
enable_encryption_support	Should be true to enable encryption support in the TGW	`bool`	`false`	no
enable_multicast_support	Whether multicast support is enabled	`bool`	`false`	no
enable_sg_referencing_support	Indicates whether to enable security group referencing support	`bool`	`true`	no
enable_vpn_ecmp_support	Whether VPN Equal Cost Multipath Protocol support is enabled	`bool`	`true`	no
name	Name to be used on all the resources as identifier	`string`	`""`	no
ram_allow_external_principals	Indicates whether principals outside your organization can be associated with a resource share.	`bool`	`false`	no
ram_name	The name of the resource share of TGW	`string`	`""`	no
ram_principals	A list of principals to share TGW with. Possible values are an AWS account ID, an AWS Organizations Organization ARN, or an AWS Organizations Organization Unit ARN	`list(string)`	`[]`	no
ram_resource_share_arn	ARN of RAM resource share	`string`	`""`	no
ram_tags	Additional tags for the RAM	`map(string)`	`{}`	no
region	Region where the resource(s) will be managed. Defaults to the region set in the provider configuration	`string`	`null`	no
share_tgw	Whether to share your transit gateway with other accounts	`bool`	`true`	no
tags	A map of tags to add to all resources	`map(string)`	`{}`	no
tgw_default_route_table_tags	Additional tags for the Default TGW route table	`map(string)`	`{}`	no
tgw_route_table_tags	Additional tags for the TGW route table	`map(string)`	`{}`	no
tgw_tags	Additional tags for the TGW	`map(string)`	`{}`	no
tgw_vpc_attachment_tags	Additional tags for VPC attachments	`map(string)`	`{}`	no
timeouts	Create, update, and delete timeout configurations for the transit gateway	object({ create = optional(string) update = optional(string) delete = optional(string) })	`null`	no
transit_gateway_cidr_blocks	One or more IPv4 or IPv6 CIDR blocks for the transit gateway. Must be a size /24 CIDR block or larger for IPv4, or a size /64 CIDR block or larger for IPv6	`list(string)`	`[]`	no
transit_gateway_route_table_id	Identifier of EC2 Transit Gateway Route Table to use with the Target Gateway when reusing it between multiple TGWs	`string`	`null`	no
vpc_attachments	Maps of maps of VPC details to attach to TGW. Type 'any' to disable type validation by Terraform.	`any`	`{}`	no

Outputs

Name	Description
ec2_transit_gateway_arn	EC2 Transit Gateway Amazon Resource Name (ARN)
ec2_transit_gateway_association_default_route_table_id	Identifier of the default association route table
ec2_transit_gateway_id	EC2 Transit Gateway identifier
ec2_transit_gateway_owner_id	Identifier of the AWS account that owns the EC2 Transit Gateway
ec2_transit_gateway_propagation_default_route_table_id	Identifier of the default propagation route table
ec2_transit_gateway_route_ids	List of EC2 Transit Gateway Route Table identifier combined with destination
ec2_transit_gateway_route_table_association	Map of EC2 Transit Gateway Route Table Association attributes
ec2_transit_gateway_route_table_association_ids	List of EC2 Transit Gateway Route Table Association identifiers
ec2_transit_gateway_route_table_default_association_route_table	Boolean whether this is the default association route table for the EC2 Transit Gateway
ec2_transit_gateway_route_table_default_propagation_route_table	Boolean whether this is the default propagation route table for the EC2 Transit Gateway
ec2_transit_gateway_route_table_id	EC2 Transit Gateway Route Table identifier
ec2_transit_gateway_route_table_propagation	Map of EC2 Transit Gateway Route Table Propagation attributes
ec2_transit_gateway_route_table_propagation_ids	List of EC2 Transit Gateway Route Table Propagation identifiers
ec2_transit_gateway_vpc_attachment	Map of EC2 Transit Gateway VPC Attachment attributes
ec2_transit_gateway_vpc_attachment_ids	List of EC2 Transit Gateway VPC Attachment identifiers
ram_principal_association_id	The Amazon Resource Name (ARN) of the Resource Share and the principal, separated by a comma
ram_resource_share_id	The Amazon Resource Name (ARN) of the resource share

Authors

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

License

Apache 2 Licensed. See LICENSE for full details.

Contributors

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