protocol:
{
  "driver": "ssh",
  "location": {
    "path": "asdf/i.qcow2",
    "server": {
      "host": "example.com",
      "port": "1234"
    }
  },
  "size": 4294967296
}

format:
{
  "driver": "qcow2",
  "file": "0123456789ABCDEF0123456789ABCDE",
  "size": 8589934590
}