Anders Nordby, Web Operations Specialist with the Møller Group in Norway, wanted to integrate Varnish Custom Statistics (VCS) with the DataDog IT monitoring and data visualization solution and wrote a blog to share how easy and useful it has been to identifying trouble spots and issues in real time.
I quite like the Varnish Custom Statistics, the idea behind it is super simple (aggregate data about classes of requests) and yet, its use cases are extremely diverse: people use it to monitor most requested URLs, to watch for brewing backend issues, to do A/B testing, or to create image walls to show the most read articles (here's the article about how it's done).
A couple of years ago we introduced the real-time statistics API with VAC. Varnish Cache provides a lot of statistics on website activity; however, in order to obtain this information it must be pulled from each server manually. Additionally, they are not available in real time. Meanwhile, Varnish Administration Console provides valuable real-time analytics across multiple instances.