How to Import an AWS Transit Gateway Route Table into Terraform

Import AWS Transit Gateway Route Table with Terraback (recommended)

Terraback reverse-engineers your live infrastructure: it reads the Amazon VPC Transit Gateway resource with read-only credentials, generates the HCL, and produces the exact import block. Two commands take you from a live AWS Transit Gateway Route Table 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_ec2_transit_gateway_route_table.example
  id = "tgw-rtb-12345678"
}

Example aws_ec2_transit_gateway_route_table configuration

Here is a realistic AWS Transit Gateway Route Table block. Terraback generates a fuller version from your actual resource attributes; this is a minimal, valid starting point.

resource "aws_ec2_transit_gateway_route_table" "example" {
  transit_gateway_id = "tgw-0123456789abcdef0"

  tags = {
    Name = "example-route-table"
  }
}

Gotchas when importing a AWS Transit Gateway Route Table

• The route table belongs to a transit gateway via transit_gateway_id, which is force-new; the parent transit gateway must already exist before import.
• The default association and default propagation route tables AWS creates with the transit gateway can be imported but are also managed by the gateway's own settings, which can cause ownership conflicts.
• Static routes, associations, and propagations are all separate child resources (aws_ec2_transit_gateway_route, _route_table_association, _route_table_propagation) and are not pulled in by importing the route table.
• After import the route table's tags and Name are tracked, but the actual routing entries inside it remain unmanaged until you import or define each route resource.

Doing it manually with terraform import

The native approach is to write the aws_ec2_transit_gateway_route_table block by hand, then run terraform import aws_ec2_transit_gateway_route_table.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