In this blog series, we’ve been looking inside Varnish to see what’s under the hood. There’s a lot more going on than meets the eye, beyond simple caching, beyond even Varnish Configuration Language.

While we have spent some time explaining all the surprising things that the Varnish private CDN solution contains under the hood, an important factor in performance is being able to understand what’s going on under the hood one level deeper, at a more diagnostic level.

Content delivery networks (CDNs) can be much more than just the workhorse of content delivery. Sure, that’s what they are designed for, but you can get much more from them if you’re able to extend their functionality -- everything from being able to create separate ‘tenants’ in your own CDN setup (for internal use or to sell CDN services on to external customers) to building in web application firewalls, cache replication, and load balancing functions, and much more.

Content can’t be king without the CDN 

In mid-2021 a handful of catastrophic commercial CDN outages made the world take notice: the supposedly decentralized internet of the future has been centralized and served through an increasingly narrow set of CDN providers, making the entire internet more vulnerable to failure. Commercial CDNs offer scale and reach, but as these outages demonstrate, lengthy outages, revenue and productivity losses, and unhappy end-users aren’t great for business.