How to Import an AWS Application/Network Load Balancer into Terraform

Import AWS Application/Network Load Balancer with Terraback (recommended)

Terraback reverse-engineers your live infrastructure: it reads the Elastic Load Balancing resource with read-only credentials, generates the HCL, and produces the exact import block. Two commands take you from a live AWS Application/Network Load Balancer 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_lb.web
  id = "arn:aws:elasticloadbalancing:us-east-1:123456789012:loadbalancer/app/web-alb/50dc6c495c0c9188"
}

Example aws_lb configuration

Here is a realistic AWS Application/Network Load Balancer block. Terraback generates a fuller version from your actual resource attributes; this is a minimal, valid starting point.

resource "aws_lb" "web" {
  name               = "web-alb"
  internal           = false
  load_balancer_type = "application"
  security_groups    = ["sg-0123456789abcdef0"]
  subnets            = ["subnet-0bb1c79de3a1b2c3d", "subnet-0cc2d8aef4b2c3d4e"]
}

Gotchas when importing a AWS Application/Network Load Balancer

• Import by the full load balancer ARN, not the name.
• Listeners (aws_lb_listener), listener rules, and target groups are separate resources you must import individually.
• load_balancer_type is immutable; you cannot convert an application load balancer to a network load balancer in place.
• Network and Gateway load balancers use subnet_mapping blocks (with optional EIP allocations) rather than a simple subnets list; copy whichever the resource uses.

Doing it manually with terraform import

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