packer example

template.json

{
  "builders": [{
    "type": "docker",
    "image": "ubuntu:14.04",
    "export_path": "nacyot-ubuntu-wget.tar"
  }],
  "provisioners": [{
      "type": "shell",
      "inline": [
        "apt-get update",
        "apt-get install -y wget"
      ]
  }],
  "post-processors": [{
      "type": "docker-import",
      "repository": "nacyot/ubuntu",
      "tag": "wget"
  }]
}