packer.json

{
"variables": {
    "aws_access_key": "",
    "aws_secret_key": "",
    "aws_region": "us-east-1",
    "version": "1.7.1",
    "revision": "0",
    "instance_type": "t2.micro",
    "image_name" : "{{ env `IMAGE_NAME` }}"
  },
  "builders": [{
    "type": "amazon-ebs",
    "access_key": "{{user `aws_access_key`}}",
    "secret_key": "{{user `aws_secret_key`}}",
    "region": "{{user `aws_region`}}",
    "instance_type": "{{user `instance_type`}}",
    "ssh_username": "ubuntu",
    "ami_name": "{{user `image_name`}}",
    "ami_regions": "{{user `aws_region`}}",
    "source_ami_filter": {
      "filters": {
      "virtualization-type": "hvm",
      "name": "ubuntu/images/*ubuntu-xenial-16.04-amd64-server-*",
      "root-device-type": "ebs"
      },
      "owners": ["099720109477"],
      "most_recent": true
    },
"launch_block_device_mappings": [
          {
            "device_name": "/dev/sda1",
            "volume_size": 30,
            "volume_type": "gp2",
            "delete_on_termination": true
          }
        ],
        "ssh_pty": "true",
        "tags": {
          "Name":        "bootstrap-{{user `owner`}}-{{user `environment`}}-{{timestamp}}",
          "Role":        "bootstrap",
          "BuildDate":   "{{isotime}}"
        }
  }],
  "provisioners": [{
    "type": "shell",
    "environment_vars": [
      "version={{user `version`}}"
    ],
    "scripts": ["packer/docker_download1.sh"]
  }]
}