Enable image caching in Rails development mode.
原理见 http://code.eoe.cn/6/title/Unicorn和Nginx部署Rails应用的css__js__img等静态资源缓存使用总结
- Add it to Gemfile
gem 'rack_image_assets_cache_control'
- setup in config/environments/development.rb
config.middleware.use(Rack::ImageAssetsCacheControl)