ubuntu.json

{
    "variables": {
        "aws_access_key":null,
        "aws_secret_key":null
    },
    "builders": [{
            "type": "amazon-ebs",
            "instance_type": "t2.micro",
            "ssh_username": "ubuntu",
            "access_key":"{{user `aws_access_key`}}",
            "secret_key":"{{user `aws_secret_key`}}",
            "ami_name": "packer {{timestamp}}",
            "source_ami_filter":{
                "filters":{
                    "virtualization-type":"hvm",
                    "name":"ubuntu/images/hvm-ssd/ubuntu-xenial-16.04-amd64-server-*",
                    "root-device-type":"ebs"
                },
                "owners":["099720109477"],
                "most_recent":true
            }
                }]
            }