In my previous post I’ve shared some bits on shipping Varnish logs to Logstash (or Heka or else?).

Recently, I have been given an opportunity to share some of my use cases for varnish logs at Dublin DevOps Meetup. Below, you’ll find the slides.

In short: What is missing from NewRelic RUM regarding website performance data and what you can get from your ELK stack is enough granularity and flexibility for thorough debugging when it comes to edge cases, such us extremely slow client (or bot, or DoS etc) screwing up averages, large image slowing down page loads, badly cached object and more.

Another contributor to page slowness, are 3rd party assets. Here, as well, RUM is not enough to find out. One can manually track down the cause using developer tools, or webpagetest.org but of course every Ops engineer wants a graph or two! Here, if you don’t know sitespeed.io yet, get yourself familiar with this excellent tool. It’s super easy to get it up and running using docker (I’m planning to write a how-to post), but if you don’t have time, you can choose to pay speedcurve.com to run sitespeed.io for you.