I'm caching the most visited page on my Rails app using HTTP caching and etags.
This is reliant on Rack::Cache, and I recently discovered I'm not explicitly setting the storage configuration for Rack::Cache anywhere in my config files or initializers (specifically, I don't have the config.action_dispatch.rack_cache bit of code anywhere, as discussed in this Heroku guide).
My implementation of HTTP caching appears to be working i.e. if a page is not modified, a logged out user gets the pages back with a 304 Not Modified response.
I fired up a Rails console from my server (in development, staging, and production), ran MyApp::Application.config.action_dispatch.rack_cache, and this is what it came back with:
=> {:metastore=>"rails:/", :entitystore=>"rails:/", :verbose=>false}
I've only ever encountered memcache, file:/, or heap:/ as options for metastore and entitystore. Never rails:/ - there's no mention of it here.
Is my Rack::Cache misconfigured? What does rails:/ mean?