assets.rb

set :max_asset_age, 2 ## Set asset age in minutes to test modified date against.

after "deploy:finalize_update", "deploy:assets:determine_modified_assets", "deploy:assets:conditionally_precompile"

namespace :deploy do
  namespace :assets do
    
    desc "Figure out modified assets."
    task :determine_modified_assets, :roles => assets_role, :except => { :no_release => true } do
      set :updated_assets, capture("find #{latest_release}/app/assets -type d -name .git -prune -o -mmin -#{max_asset_age} -type f -print", :except => { :no_release => true }).split
    end
    
    desc "Remove callback for asset precompiling unless assets were updated in most recent git commit."
    task :conditionally_precompile, :roles => assets_role, :except => { :no_release => true } do
      if(updated_assets.empty?)
        callback = callbacks[:after].find{|c| c.source == "deploy:assets:precompile" }
        callbacks[:after].delete(callback)
        logger.info("Skipping asset precompiling, no updated assets.")
      else
        logger.info("#{updated_assets.length} updated assets. Will precompile.")
      end
    end
    
  end
end