<http://howtonode.org/promises> The majority of functions that take Node-style callbacks are suitable for wrapping in a Promise. Any Node-style callback function that only calls its callback one time may be wrapped. The following function is taken from Bogart.

promisify

function promisify(nodeAsyncFn, context) {
  return function() {
    var defer = q.defer()
      , args = Array.prototype.slice.call(arguments);

    args.push(function(err, val) {
      if (err !== null) {
        return defer.reject(err);
      }

      return defer.resolve(val);
    });

    nodeAsyncFn.apply(context || {}, args);

    return defer.promise;
  };
};