Let's say you have the following files on your Terraform server.

├── required_providers.tf
├── amazon_machine_images (directory)
│   ├── data.tf
│   ├── outputs.tf
│   ├── provider.tf

required_providers.tf will almost always have this.

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
    }
  }
}

Let's say provider.tf has the following. In this example, the "default" profile in /home/username/.aws/config and /home/username/.aws/credentials is being used. This assumes you have setup Terraform as described in Amazon Web Services (AWS) - Getting Started with Terraform.

provider "aws" {
  alias   = "default"
  profile = "default"
  region  = "default"
}

And data.tf contains something like this.

data "aws_ami" "most-recent-ecs-optimized-image" {
  most_recent = true

  filter {
    name   = "name"
    values = ["amzn-ami*ecs-optimized"]
  }
}

The terraform refresh command should return something like this, the ID of the most recent ECS optimized image.

data.aws_ami.most-recent-ecs-optimized-image: Read complete after 1s [id=ami-012310613ab7ed9d0]