VPC Modules 0.28.1Last updated in version 0.27.0

Transit Gateway Route Module

View Source Release Notes

This module creates a route for each CIDR block in a list cidr_blocks to a transit gateway route table. The route can be directed to any attachment within the transit gateway or can be configured as a blackhole route. A blackhole route is useful to drop traffic to a given CIDR block, or can be utilized to flush downstream route tables of ephemeral routes.

See VPC Core Concepts for more information on the core networking components and topologies.

[!IMPORTANT] This module may require additional modules or configuration. Other modules, such as the route module, may be required to complete the route configuration. This module is intended to be used as a building block for more complex network topologies.

What is a Transit Gateway Route?

A transit gateway route is a way to route traffic between VPCs, peers, VPNs, and other transit gateway attachments. You can think of a transit gateway route just like a route on a router. By creating a route, you're telling the transit gateway how to route traffic to a given CIDR block. By creating a route and then attaching the transit gateway to a VPC, you can route traffic between VPCs. Where possible, we recommend utilizing dynamic routing either by way of propagation or BGP. This simplifies the management of routes and ensures that routes are automatically updated when attachments are added or removed.

Usage

For usage examples, check out the examples folder.

Requirements

Name	Version
terraform	>= 1.0.0
aws	>= 4.5.0

Providers

Name	Version
aws	>= 4.5.0

Modules

No modules.

Resources

Name	Type
aws_ec2_transit_gateway_route.this	resource

Inputs

Name	Description	Type	Default	Required
cidr_blocks	A list of IPv4 or IPv6 CIDR blocks used for destination matches. Routing decisions are based on the most specific match.	list(string)	n/a	yes
enable_blackhole	Indicates whether to drop traffic that matches this route (blackhole). Cannot use with 'transit_gateway_attachment_id' Defaults to false.	bool	false	no
transit_gateway_attachment_id	Identifier of Transit Gateway Attachment (required for propagation). Cannot use with 'enable_blackhole'. Default is null.	string	null	no
transit_gateway_route_table_id	Identifier of Transit Gateway Route Table	string	n/a	yes

Outputs

Name	Description
id	Map of ids of the transit gateway routes.

Sample Usage

Terraform

main.tf

# ------------------------------------------------------------------------------------------------------
# DEPLOY GRUNTWORK'S TRANSIT-GATEWAY-ROUTE MODULE
# ------------------------------------------------------------------------------------------------------

module "transit_gateway_route" {

  source = "git::git@github.com:gruntwork-io/terraform-aws-vpc.git//modules/transit-gateway-route?ref=v0.28.1"

  # ----------------------------------------------------------------------------------------------------
  # REQUIRED VARIABLES
  # ----------------------------------------------------------------------------------------------------

  # A list of IPv4 or IPv6 CIDR blocks used for destination matches. Routing
  # decisions are based on the most specific match.
  cidr_blocks = <list(string)>

  # Identifier of Transit Gateway Route Table
  transit_gateway_route_table_id = <string>

  # ----------------------------------------------------------------------------------------------------
  # OPTIONAL VARIABLES
  # ----------------------------------------------------------------------------------------------------

  # Indicates whether to drop traffic that matches this route (blackhole).
  # Cannot use with 'transit_gateway_attachment_id' Defaults to false.
  enable_blackhole = false

  # Identifier of Transit Gateway Attachment (required for propagation). Cannot
  # use with 'enable_blackhole'. Default is null.
  transit_gateway_attachment_id = null

}

Terragrunt

terragrunt.hcl

# ------------------------------------------------------------------------------------------------------
# DEPLOY GRUNTWORK'S TRANSIT-GATEWAY-ROUTE MODULE
# ------------------------------------------------------------------------------------------------------

terraform {
  source = "git::git@github.com:gruntwork-io/terraform-aws-vpc.git//modules/transit-gateway-route?ref=v0.28.1"
}

inputs = {

  # ----------------------------------------------------------------------------------------------------
  # REQUIRED VARIABLES
  # ----------------------------------------------------------------------------------------------------

  # A list of IPv4 or IPv6 CIDR blocks used for destination matches. Routing
  # decisions are based on the most specific match.
  cidr_blocks = <list(string)>

  # Identifier of Transit Gateway Route Table
  transit_gateway_route_table_id = <string>

  # ----------------------------------------------------------------------------------------------------
  # OPTIONAL VARIABLES
  # ----------------------------------------------------------------------------------------------------

  # Indicates whether to drop traffic that matches this route (blackhole).
  # Cannot use with 'transit_gateway_attachment_id' Defaults to false.
  enable_blackhole = false

  # Identifier of Transit Gateway Attachment (required for propagation). Cannot
  # use with 'enable_blackhole'. Default is null.
  transit_gateway_attachment_id = null

}

Reference

Inputs

Required

cidr_blockslist(string)required

A list of IPv4 or IPv6 CIDR blocks used for destination matches. Routing decisions are based on the most specific match.

transit_gateway_route_table_idstringrequired

Identifier of Transit Gateway Route Table

Optional

enable_blackholebooloptional

Indicates whether to drop traffic that matches this route (blackhole). Cannot use with 'transit_gateway_attachment_id' Defaults to false.

Default:false

transit_gateway_attachment_idstringoptional

Identifier of Transit Gateway Attachment (required for propagation). Cannot use with 'enable_blackhole'. Default is null.

Default:null

Outputs

id

Map of ids of the transit gateway routes.