How to Import an AWS Transit Gateway Peering Attachment into Terraform

Import AWS Transit Gateway Peering Attachment 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 Peering Attachment 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_peering_attachment.example
  id = "tgw-attach-12345678"
}

Example aws_ec2_transit_gateway_peering_attachment configuration

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

resource "aws_ec2_transit_gateway_peering_attachment" "example" {
  peer_account_id         = "123456789012"
  peer_region             = "us-west-2"
  peer_transit_gateway_id = "tgw-0fedcba9876543210"
  transit_gateway_id      = "tgw-0123456789abcdef0"

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

Gotchas when importing a AWS Transit Gateway Peering Attachment

• This is the requester side of a cross-region or cross-account peering; the accepter side is a separate aws_ec2_transit_gateway_peering_attachment_accepter resource imported with the same tgw-attach ID in the peer account/region.
• peer_region, peer_account_id, and peer_transit_gateway_id are all force-new; editing any of them after import destroys and recreates the peering.
• A peering attachment can be imported even while pendingAcceptance, but routing will not work until the accepter resource is in place and the attachment is available.
• Routes that use this attachment live in aws_ec2_transit_gateway_route resources on a route table; importing the attachment does not import the routes that reference it.

Doing it manually with terraform import

The native approach is to write the aws_ec2_transit_gateway_peering_attachment block by hand, then run terraform import aws_ec2_transit_gateway_peering_attachment.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