build.json

{
  "variables": {
    "aws_region": "us-east-1"
  },
  "builders": [{
    "ami_name": "terratest-packer-example-{{isotime | clean_ami_name}}",
    "ami_description": "An example of how to create a custom AMI on top of Ubuntu",
    "instance_type": "t2.micro",
    "region": "{{user `aws_region`}}",
    "type": "amazon-ebs",
    "source_ami_filter": {
      "filters": {
        "virtualization-type": "hvm",
        "architecture": "x86_64",
        "name": "*ubuntu-xenial-16.04-amd64-server-*",
        "block-device-mapping.volume-type": "gp2",
        "root-device-type": "ebs"
      },
      "owners": ["099720109477"],
      "most_recent": true
    },
    "ssh_username": "ubuntu",
    "encrypt_boot": false
  }],
  "provisioners": [{
    "type": "shell",
    "inline": [
      "DEBIAN_FRONTEND=noninteractive sudo apt-get update",
      "DEBIAN_FRONTEND=noninteractive sudo apt-get upgrade -y"
    ]
  }]
}