git_util.rb

# coding: UTF-8
class GitUtil
  class << self
    # Current source code revision
    def revision
      rev = capistrano_revision
      rev = command_revision unless rev
      rev.try(:chomp)
    end

    private
    def capistrano_revision
      begin
        revision_file = "#{Rails.root}/REVISION"
        return File.read(revision_file) if File.exists? revision_file
      rescue IOError => e
        Rails.logger.info(e)
      end
      nil
    end

    def command_revision
      rev = `cd '#{Rails.root}' && git rev-list --max-count=1 HEAD`
      $? == 0 ? rev : nil
    end
  end
end