Packer JSON input to create an AMI with amazon-ebs driver

packer.json

{
  "variables": {
    "aws_access_key_id": "{{env `AWS_ACCESS_KEY_ID` }}", 
    "aws_secret_key": "{{env `AWS_SECRET_ACCESS_KEY` }}",
    "aws_region": "{{env `AWS_REGION` }}",
    "ebs_optimized": "{{env `AMI_EBS_OPTIMIZED` }}",
    "source_ami": "{{env `AWS_SOURCE_AMI` }}",
    "instance_type": "{{env `AMI_INSTANCE_TYPE` }}",
    "associate_public_ip_address": "{{env `AMI_ASSOCIATE_PUBLIC_IP_ADDRESS` }}",
    "vpc_id": "{{env `AMI_VPC_ID` }}",
    "subnet_id": "{{env `AMI_SUBNET_ID` }}",
    "security_group_id": "{{ env `AWS_SECURITY_GROUP_ID` }",
    "ami_name": "{{ env `AMI_NAME` }}",
    "ci_build_ref": "{{ env `$CI_BUILD_REF` }}"
  },
  "builders": [
    { 
      "type": "amazon-ebs",
      "access_key": "{{user `aws_access_key_id` }}",
      "secret_key": "{{user `aws_secret_key` }}",
      "ami_regions": "{{user `aws_region` }}",
      "source_ami": "{{user `source_ami` }}",
      "ami_name": "{{user `ami_name` }}",
      "ami_description": "Image with docker engine and TODO express images",
      "region": "{{user `aws_region` }}",
      "ebs_optimized": "{{ user `aim_ebs_optimized` }}",      
      "instance_type": "{{ user `instance_type` }}",
      "associate_public_ip_address": "{{ user `associate_public_ip_address` }}",
      "vpc_id": "{{user `vpc_id` }}",
      "subnet_id": "{{user `subnet_id` }}",
      "ssh_username": "{{user `ssh_username` }}",
      "security_group_id": "{{user `security_group_id` }}",
      "ssh_keypair_name": "packer-key",
      "ssh_private_key_file": "./packer-key.pem",
      "tags":
        {
          "Group": "TechTalk",
          "Name": "TechTalk-TODO-App",
          "SHA1": "{{user `ci_build_ref` }}"
        }     
    }   
  ],  

  "provisioners" : [ 
    { "type": "chef-solo",
      "cookbook_paths": [ "vendor/cookbooks" ],
      "run_list": [ "techtalk::default" ]
    }
  ]
}