title: (HA)Proxy with mutual TLS/SSL auth
body: <p>Problem: I have an application connecting to several databases (Redis, Riak, etc) via TCP through HAProxy. Like this:
  app -> HAProxy --TLS--> HAProxy -> Redis</p>
  
  <p>Access to HAProxy on Redis side is managed by Chef via iptables. We already use CFSSL for mutual TLS authentication on Nginx&lt;->Nginx connections because it's way faster than waiting until Chef updates configuration.</p>
  
  <p>Wanna make HAProxy on application side use client-side TLS certificate when connecting to HAProxy on DB side.</p>
  
  <p>Actually any other proxy will do on client side but we'd like to keep things simple.</p>