How to Import an AWS Classic Load Balancer into Terraform

Import AWS Classic 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 Classic 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_elb.legacy
  id = "legacy-web-elb"
}

Example aws_elb configuration

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

resource "aws_elb" "legacy" {
  name            = "legacy-web-elb"
  subnets         = ["subnet-0bb1c79de3a1b2c3d"]
  security_groups = ["sg-0123456789abcdef0"]

  listener {
    instance_port     = 80
    instance_protocol = "http"
    lb_port           = 80
    lb_protocol       = "http"
  }

  health_check {
    target              = "HTTP:80/"
    interval            = 30
    timeout             = 5
    healthy_threshold   = 2
    unhealthy_threshold = 2
  }
}

Gotchas when importing a AWS Classic Load Balancer

• aws_elb is the legacy Classic Load Balancer; Application and Network Load Balancers use aws_lb and import by ARN instead.
• Import by the load balancer name, not by ARN; Classic ELB names are limited to 32 characters.
• Instance attachments can be inline or a separate aws_elb_attachment resource; do not mix the two.
• AWS is steering customers off Classic Load Balancers, so consider migrating to aws_lb rather than expanding ELB usage.

Doing it manually with terraform import

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