Varnish: Debrief

Today, we just released the Varnish-ed site I posted about a few days ago. A few things to be careful about in your Varnish deployment (that I had originally overlooked):

  • Make sure you’re 301 redirecting traffic to your canonical name ( to, or vice versa)
  • Do this redirecting within Varnish! I had strange problems when applying this logic within Apache.
  • If you insist on applying the redirection logic within Apache, you may run into a problem where the Varnish health-check “probes” will fail (and deem your backend “sick”, throwing 503 errors at everyone after the grace period has expired).