Persistent connections timeout (keepalive on upstream)

[ionut_rusu]

The short question is how can be set the timeout for an upstream for
persistent connections (using keepalive) - looks like they never timeout.

Details:

I have a configuration where i need to setup a reverse proxy for SSL
connections, and reuse the backend SSL connections. For doing this i'm using
the keepalive directive on the upstream, something like this:

...
  upstream backend {
        server backend-host.com:443;
        keepalive 10;
   }
...

backend-host.com is hosted on Amazon AWS and consists of an Elastic Load
Balancer. This means that from time to time its IP will change (scaling up
and down)

My issue is that witth the current configuration the persistent connections
are never refreshed (they don't have a timeout) and when the IP of the ELB
changes then the nginx reverse proxy stops working.  

Let me know if more info is needed.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,261284,261284#msg-261284