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Welcome to this step-by-step guide on importing existing AWS resources into OpenTofu. By the end of this tutorial, you’ll know how to discover unmanaged resources, import an EC2 instance, and manage it alongside your Terraform code.

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Prerequisites

  • OpenTofu CLI installed
  • AWS CLI configured for LocalStack (or your AWS account)
  • A project directory named project-jade

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1. Initialize the Project Directory

Open your terminal and navigate to the project-jade folder: 
cd flashroot/opentofu-projects/project-jade/

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2. Review the Existing Terraform Configuration

Below is the current HCL setup. It defines an AWS provider, global variables, and a set of EC2 instances: 
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "4.15.0"
    }
  }
}

provider "aws" {
  region                       = "us-east-1"
  skip_credentials_validation  = true
  skip_requesting_account_id   = true
  endpoints {
    ec2 = "http://aws:4566"
  }
}

variable "name" {
  type    = set(string)
  default = ["jade-webserver", "jade-lbr", "jade-app1", "jade-app2"]
}

variable "ami" {
  default = "ami-0c9bfc21ac5bf10eb"
}

variable "instance_type" {
  default = "t2.nano"
}

variable "key_name" {
  default = "jade"
}

resource "aws_instance" "ruby" {
  for_each      = var.name
  ami           = var.ami
  instance_type = var.instance_type
  key_name      = var.key_name

  tags = {
    Name = each.value
  }
}

output "instances" {
  value = aws_instance.ruby
}
VariableDescriptionExample Default
var.nameSet of EC2 instance names["jade-webserver","jade-lbr","..."]
var.amiAMI ID for all instances"ami-0c9bfc21ac5bf10eb"
var.instance_typeEC2 instance type"t2.nano"
var.key_nameSSH key pair name"jade"

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3. Identify Unmanaged Resources

To list all resources tracked in state versus your code, run: 
tofu show
Compare this output with your HCL.
Question: Which resource appears in the state but not in the configuration?
Answer: An EC2 instance (e.g., jade-agent) that wasn’t defined in code.

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4. Provision the SSH Key Pair

OpenTofu did not create the jade key pair—it was generated via AWS CLI: 
aws ec2 create-key-pair \
  --endpoint http://aws:4566 \
  --key-name jade \
  --query 'KeyMaterial' \
  --output text > jade.pem
This command writes the private key to jade.pem.
Keep your private keys out of version control. Add jade.pem to .gitignore.

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5. Locate the External EC2 Instance ID

Another EC2 instance named Jade-MW was created manually. Retrieve its Instance ID: 
aws ec2 describe-instances --endpoint http://aws:4566
The image shows a split screen with a task description on the left about creating and inspecting an AWS EC2 instance using the AWS CLI, and a code editor on the right displaying Terraform configuration files for setting up an AWS instance.
Sample JSON excerpt: 
{
  "Reservations": [
    {
      "Instances": [
        {
          "ImageId": "ami-0b32bca746b12849",
          "InstanceId": "i-1bd18cac05184c14",
          "InstanceType": "t2.large",
          "KeyName": "jade",
          ...
        }
      ]
    }
  ]
}
Instance ID: i-1bd18cac05184c14

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6. Import the EC2 Instance into OpenTofu

  1. Create an empty resource block in main.tf: 
    resource "aws_instance" "jade-mw" {
}
  2. Import the existing EC2 resource: 
    tofu import aws_instance.jade-mw i-1bd18cac05184c14

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7. Complete the Imported Resource Definition

After import, running tofu apply will show missing arguments. Inspect the imported state: 
tofu show
Then update main.tf with the required properties: 
resource "aws_instance" "jade-mw" {
  ami           = "ami-0b32bca746b12849"
  instance_type = "t2.large"
  key_name      = "jade"

  tags = {
    Name = "jade-mw"
  }
}
You can always re-run tofu show to confirm attribute names and values for any imported resource.

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8. Validate the Configuration

Run a plan to ensure no changes are pending: 
tofu plan
You should see 0 to add, 0 to change, 0 to destroy.
The image shows a coding environment with a task to update a resource configuration using Terraform. The code editor displays a resource block for an AWS instance, and the terminal shows the execution plan output.
Congratulations! You’ve successfully imported and now manage an existing AWS EC2 instance with OpenTofu.

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References

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