Logging with log level and Process id. $$ is the pid Put simple_formatter in config/initializers Apparently for Unicorn on Heroku apps you are supposed to add put_in_application to application.rb within class Application < Rails::Application

put_in_application.rb

    if Rails.env[/production|staging/]
      config.logger = Logger.new(STDOUT)
      config.logger.level = Logger.const_get(ENV['LOG_LEVEL'] ? ENV['LOG_LEVEL'].upcase : 'INFO')
    end

simple_formatter.rb

class Logger::SimpleFormatter
  # This method is invoked when a log event occurs
  def call(severity, timestamp, progname, msg)
    "[#{severity}] [#{$$}] #{String === msg ? msg : msg.inspect}\n"
  end
end