This AWS Lambda can be used to check your website for availability

lambda-website-checker.js

'use strict';

var url = require('url');
var target = 'http://www.yourwebsite.com'; // Change this one

exports.handler = function(event, context, callback) {
  var urlObject = url.parse(target);
  var mod = require(
    urlObject.protocol.substring(0, urlObject.protocol.length - 1)
  );
  console.log('[INFO] - Checking ' + target);
  var req = mod.request(urlObject, function(res) {
    res.setEncoding('utf8');
    res.on('data', function(chunk) {
      console.log('[INFO] - Read body chunk');
    });
    res.on('end', function() {
      console.log('[INFO] - Response end');
      callback();
    });
  });

  req.on('error', function(e) {
    console.log('[ERROR] - ' + e.message);
    callback(e);
  });
  req.end();
};

Do you really use this to monitor your website? Do you find Lambda reliable enough for such a purpose?

1. Because Lambda has failure built-in as a feature so-to-speak, and relies on the user to anticipate failures, I find Lambda gives more false positives then any other monitoring system I've tried.
2. The alert e-mails generated are insanely verbose, while at the same time not supplying much useful information like what went wrong.
3. Timezone usage seems inconsistent and confusing in the Cloudwatch Log Groups, it takes forever to find relevant entries, if I can find it at all.