How to Import an AWS Transit Gateway Connect into Terraform

Import AWS Transit Gateway Connect 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 Connect 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_connect.example
  id = "tgw-attach-12345678"
}

Example aws_ec2_transit_gateway_connect configuration

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

resource "aws_ec2_transit_gateway_connect" "example" {
  transport_attachment_id = "tgw-attach-87654321"
  transit_gateway_id      = "tgw-0123456789abcdef0"

  tags = {
    Name = "example-connect"
  }
}

Gotchas when importing a AWS Transit Gateway Connect

• A Connect attachment rides on top of an existing transport attachment (a VPC or DX Gateway attachment); transport_attachment_id points at that parent, which must already exist before import.
• protocol only supports the value gre; do not try to change it, and leave it at the default or AWS rejects the apply.
• The associated aws_ec2_transit_gateway_connect_peer (the GRE/BGP peer) is a separate resource with its own tgw-connect-peer ID and must be imported on its own.
• Once created, transport_attachment_id and transit_gateway_id are immutable; editing them after import forces a destroy and recreate of the Connect attachment.

Doing it manually with terraform import

The native approach is to write the aws_ec2_transit_gateway_connect block by hand, then run terraform import aws_ec2_transit_gateway_connect.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