google apps script=js

siteUptimeMonitor.js

var ONE_S = 1000,
    ONE_M = 60*ONE_S,
    ONE_H = 60*ONE_M,
    
    RUN_EVERY = 5*ONE_M,
    SLEEP_TIME = 30*ONE_M,
    
    CHECK_URL = 'http://www.SITE.com',
    NOTIFY_MAIL = 'EMAIL@EMAIL.com',
    NOTIFY_CALENDAR = 'ID_OF_YOUR_GOOGLE_CALENDAR@group.calendar.google.com';

function main() {
  try {
    testRunner(NOTIFY_CALENDAR, NOTIFY_MAIL, CHECK_URL);
  } catch(error) {
    MailApp.sendEmail(NOTIFY_MAIL, '[siteUptimeMonitor] ERROR testing ' + CHECK_URL, error);
  }
}
  
function testRunner(calID, mail, url) {
  var current_timestamp = new Date().getTime(),
      cal = CalendarApp.getCalendarById(calID),
      events = cal.getEvents(new Date(current_timestamp-ONE_H), new Date(current_timestamp)),
      last_run = events.length ? events[events.length-1] : '',
      last_run_status = last_run ? JSON.parse(last_run.getDescription()) : '';
  
  Logger.log(cal.getName());
  Logger.log(last_run);  
  
  if (last_run && last_run_status.is_success) {
    if (current_timestamp - last_run_status.timestamp < SLEEP_TIME) {
      // sleep time
      return;
    } 
  }

  var status = testPage(url);
  saveEvent(calID, mail, last_run, last_run_status, current_timestamp, status);
}

function testPage(url){
  var status = {url: url, is_success: true, msg: 'OK', code: '', timestamp: new Date().getTime()};
  
  try {
    response = UrlFetchApp.fetch(url);
  } catch(error) {
    status.is_success = false;
    status.msg = error
    return status;
  }
    
  status.code = response.getResponseCode();
  if (status.code != 200) { // 2xx + 3xx ?
    status.is_success = false;
    status.msg = response.getContentText();
  }
  
  return status;
}

function saveEvent(calID, mail, last_run, last_run_status, current_timestamp, status) {
  var d = new Date(current_timestamp),
      dateString = ""+ d.getFullYear() +"-"+ (d.getMonth()+1) +"-"+ d.getDate() +" "+ d.getHours() +":"+ d.getMinutes() +":"+ d.getSeconds(),
      cal = CalendarApp.getCalendarById(calID),
      title = '',
      body = '';
  
  status.run_at = dateString;
  
  /* Mail: 
     on any fail OR on status change */
  if (!status.is_success) { 
    title = '[siteUptimeMonitor] ' + status.url + ' !!!is DOWN!!!';
    body = 'Run at: ' + dateString; +'\nCode: '+ status.code +'\nMessage: '+ status.msg;
    MailApp.sendEmail(mail, title, body);
  } else if (last_run && last_run_status.is_success != true) {
    title = '[siteUptimeMonitor] ' + status.url + ' is back OK';
    body = 'Run at: ' + dateString; +'\nCode: '+ status.code;
    MailApp.sendEmail(mail, title, body);
  }
  
  /* Calendar: 
     new event on status change OR update previous */
  title = status.is_success ? status.msg : '' + status.code + '!!!';
  body = JSON.stringify(status);

  if (!last_run || last_run_status.is_success != status.is_success) {
    var startTime = new Date(current_timestamp),
        endTime = status.is_success ? new Date(current_timestamp+SLEEP_TIME) : new Date(current_timestamp+RUN_EVERY);
    var event = cal.createEvent(title, startTime, endTime, {description: body});
    if (last_run) {
      event.addSmsReminder(0);
    }
  } else {
    // - different errors 404, 501... - just offer write with most recent
    var startTime = last_run.getStartTime(),
        endTime = new Date(current_timestamp+RUN_EVERY);
    var event = cal.createEvent(title, startTime, endTime, {description: body});
    last_run.deleteEvent();
  }
}