Disadvantages to rack-cache vs. Varnish in Heroku cedar stack?

Question

The previous 2 Heroku application stacks came with a Varnish layer which automatically reverse-proxy-cached content based on http headers.

The new Heroku cedar stack doe

Answer 1

A more modern answer, with 20/20 hindsight:

To get the caching performance approaching that of bamboo on cedar-14, this is the usual pattern:

1. Configure Rails to generate appropriate caching headers (i.e., Etags, Cache-Control, Last-Modified, etc.)
2. Stick fastly (varnish as a service) or cloudflare in front of your app. If app headers were set correctly, profile-like pages that need to be fresh won't be cached, as opposed to static assets.

I would recommend redis-rails as a rack cache backend, if you're doing caching at multiple layers (FE (CF/FY), page, action, fragment, etc.).