You can use Google Apps Script with the Google URL Shortener API to convert any long URL into a short one served through the goo.gl domain. Make sure you replace key with your own key from the Google Console dashboard. You can also bit.ly to shorten URLs.

function shortenURL(longUrl) {
  var key = 'YOUR_KEY';
  var serviceUrl = 'https://www.googleapis.com/urlshortener/v1/url?key=' + key;

  var options = {
    muteHttpExceptions: true,
    method: 'post',
    contentType: 'application/json',
    payload: JSON.stringify({ longUrl: longUrl }),
  };

  var response = UrlFetchApp.fetch(serviceUrl, options);

  if (response.getResponseCode() == 200) {
    var content = JSON.parse(response.getContentText());
    if (content != null && content['id'] != null) return content['id'];
  }

  return longUrl;
}

The other easier alternative for creating short URLs with the Google URL shortener API doesn’t require you to create a key as it passes the OAuth 2.0 access token for the current user in the header.

function shortenUrl(longURL) {
  var url = 'https://www.googleapis.com/urlshortener/v1/url';

  var payload = { longUrl: longURL };

  var parameters = {
    method: 'post',
    headers: { Authorization: 'Bearer ' + ScriptApp.getOAuthToken() },
    payload: JSON.stringify(payload),
    contentType: 'application/json',
    muteHttpExceptions: true,
  };

  var response = UrlFetchApp.fetch(url, parameters);

  Logger.log(response);
}