how to config log level within production env rails + unicorn

production.rb

  # Set to :debug to see everything in the log.
  config.log_level = ENV["LOG_LEVEL"].present? ? ENV["LOG_LEVEL"] : :info

unicorn.rb

before_fork do |server, worker|
  ENV["LOG_LEVEL"] = "debug"

  old_pid = "#{app_path}/tmp/pids/unicorn.pid.oldbin"
  if File.exists?(old_pid) && server.pid != old_pid
    begin
      Process.kill("QUIT", File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
      puts "Send 'QUIT' signal to unicorn error!"
    end
  end
end