[ochoseis]

Two questions: (1) Anyone use Varnish in front of Rails? Is it better to just set up some memcached and/or redis and let the app handle it? (2) To deal with session-specific stuff, how common is it to render some common plain html views, then fill in the particulars with JS/Ajax? If you need to support no-JS (heaven forbid) do people use iframes?

[seanp2k2]

Check out ESI blocks: https://www.varnish-cache.org/trac/wiki/ESIfeatures

Varnish will very likely be an order of magnitude or two faster than sending requests to your app. You can get going with a simple config in a few minutes and without breaking anything (just have varnish listen on a different port and use :80 or your app server as the back-end), so I'd strongly suggest playing with it if you're curious. It's pretty impressively fast software, and VCL gives you an awesome abstraction for controlling how the cache handles different routes.

[ruben_varnish]

Answer to (1): Heroku used Varnish in front of EVERYTHING in their previous stack... So I guess that means that whatever Ruby (or RoR) app you are running you should look into using Varnish.