Penumbra
Just a shadow of sunspot/solr/whathave you. Creates JSON-stored Indexes, possibly collected into Catalogs. Really, it's just a bunch of hashes. Hashes all the way down! Hashes, I say!
Installation
Add this line to your application's Gemfile:
gem 'penumbra'
And then execute:
$ bundle
Or install it yourself as:
$ gem install penumbra