Override how rails computes asset tags to work in multi-server deployments via git commits

gistfile1.rb

# Override how rails computes asset tags to work in multi-server deployments via git commits
module ActionView
  module Helpers
    module AssetTagHelper

      def rails_asset_id(source)
        if asset_id = ENV["RAILS_ASSET_ID"]
          asset_id
        else
          if @@cache_asset_timestamps && (asset_id = @@asset_timestamps_cache[source])
            asset_id
          else
            path = File.join(ASSETS_DIR, source)
            asset_id = File.exist?(path) ? `git log --format="%H" --max-count=1 #{path}`[0..12] : ''

            if @@cache_asset_timestamps
              @@asset_timestamps_cache_guard.synchronize do
                @@asset_timestamps_cache[source] = asset_id
              end
            end

            asset_id
          end
        end
      end
    end
  end
end