This is a guest post by Michael Schenck, SRE Staff Engineer at Tumblr.
At Tumblr, blogs (or Tumblelog) are one of our most highly trafficked faces on the internet. One of the most convenient aspects of tumblelogs is their highly cacheable nature, which is fantastic because of the high views/post ratio the Tumblr network offers our users. That said, it's not entirely trivial to scale out the perimeter proxy tier, let alone the caching tier, necessary for serving all of those requests.
This article describes the architecture of the portion of our perimeter responsible for blogs serving, one of our more highly trafficked perimeter end-points.
Here's how we do it.