title: Which HTTP status code should I use for a health-check failure?
body: <p>I'm implementing a <code>/_status/</code> endpoint which does some sanity checks on data in our database. </p>
  
  <p>For example, we are collecting measurements and the status should go "bad" if the latest measurement is over an hour old.</p>
  
  <p>I would like to point Pingdom at this URL to leverage their alerting infrastructure and tell us when something's wrong.</p>
  
  <p>On a "good" status I will serve an HTML page with an HTTP 200 OK status. But what would an appropriate HTTP status code be for "bad"? Or would it be more correct not to convey this information via status code, but via HTML content instead?</p>
  
  <p>Thanks!</p>