Beautiful Logging for Ruby on Rails 3.2

UPDATE: Go here for the Rails 4 version…

In my previous post I showed you a simple way to get beautiful, easy-to-read logs in your Rails application. That trick stopped working in Rails 3.2. So for Rails 3.1 or earlier, refer to my earlier post; but for 3.2 on, read on…

It’s really easy. Just make a new file in your ‘config/initializers’ directory called something like ‘log_formatting.rb’ and paste into it the following code. Restart your app, and voila: pretty logs again!

class ActiveSupport::BufferedLogger
  def formatter=(formatter)
    @log.formatter = formatter
  end
end

class Formatter
  SEVERITY_TO_TAG_MAP     = {'DEBUG'=>'meh', 'INFO'=>'fyi', 'WARN'=>'hmm', 'ERROR'=>'wtf', 'FATAL'=>'omg', 'UNKNOWN'=>'???'}
  SEVERITY_TO_COLOR_MAP   = {'DEBUG'=>'0;37', 'INFO'=>'32', 'WARN'=>'33', 'ERROR'=>'31', 'FATAL'=>'31', 'UNKNOWN'=>'37'}
  USE_HUMOROUS_SEVERITIES = true

  def call(severity, time, progname, msg)
    if USE_HUMOROUS_SEVERITIES
      formatted_severity = sprintf("%-3s","#{SEVERITY_TO_TAG_MAP[severity]}")
    else
      formatted_severity = sprintf("%-5s","#{severity}")
    end

    formatted_time = time.strftime("%Y-%m-%d %H:%M:%S.") << time.usec.to_s[0..2].rjust(3)
    color = SEVERITY_TO_COLOR_MAP[severity]

    "\033[0;37m#{formatted_time}\033[0m [\033[#{color}m#{formatted_severity}\033[0m] #{msg.strip} (pid:#{$$})\n"
  end

end

Rails.logger.formatter = Formatter.new

Credit for figuring out how to get log formatting working with Rails 3.2 goes to JRochkind. If you’d like a complete log formatting solution in the form of a gem, see his FormattedRailsLogger gem at Github.