Guidance for Auto-Generated Configuration from a Plannable Import

Introduction

You can automatically generate Terraform configuration for existing infrastructure using plannable imports. This feature, introduced as an experiment in Terraform 1.5, requires careful manual review before you apply any changes.

Scenario

You want to automatically generate Terraform configuration for an existing resource by using the terraform plan command with the -generate-config-out flag.

$ terraform plan -generate-config-out=generated_resources.tf

This command works in conjunction with an import block in your configuration, such as the following example.

import {
  to = aws_instance.ec2
  id = "i-REDACTED"
}

Recommendation

Always review the automatically generated configuration for accuracy and address any warnings produced in the console from this experimental Terraform feature.

1. Prune Default Values: The generated configuration may include attributes with default values that Terraform would normally supply. You should remove these optional attributes to avoid reliance on otherwise-default values.

   For example, review the following output and remove attributes like ebs_optimized = false if that is the default behavior.

   resource "aws_instance" "ec2" {
     ami                           = "ami-REDACTED"
     associate_public_ip_address   = true
     availability_zone             = "us-east-1c"
     disable_api_stop              = false
     disable_api_termination       = false
     ebs_optimized                 = false
     get_password_data             = false
     hibernation                   = false
     host_id                       = null
     ## generated configuration continues but is omitted for brevity
   }

2. Review the Subsequent Plan: After refining the generated configuration, run terraform plan again. Pay close attention to the execution plan to ensure the difference (or lack of difference) between your current state and desired state is correct before you run terraform apply.

Additional Information

Please refer to the official documentation on Generating Configuration with Plannable Imports.