function doGet() {
  loadFile('DOCUMENT ID');
  //your app entry here
}

function bootstrap() {
  //reference permissions you might need
  Browser.msgBox('');
}

function loadFile(fileId) {
  var fileContent = DocsList.getFileById(fileId).getContentAsString();
  try {
    eval(fileContent);
  } catch (e) {
    var fileName = DocsList.getFileById(fileId).getName();
    e.message = [
      "fileName", "line " + e.lineNumber, e.message
    ].join(" | ");
    throw e;
  }
}