title: Load balancing with nginx
body: <p>I want to stop serving requests to my back end servers if the load on those servers goes above a certain level. Anyone who is already surfing the site will still get routed but new connection will be sent to a static server busy page until the load drops below a pre determined level.</p>
  
  <p>I can use cookies to let the current customers in but I can't find information on how to to routing based on a custom load metric.</p>
  
  <p>Can anyone point me in the right direction? </p>