the $upstream_addr variable is empty when enable keepalive

[Maxim Dounin]

Hello!

On Thu, Apr 26, 2012 at 10:11:48AM +0800, kindy wrote:

> hi,
> 
> from nginx 1.1.13 to 1.2.0.
> the conf:
> 
> upstream a {
>     server 127.0.0.1:8083;
>     keepalive 10 single;

Don't use "single", it's intentionally left undocumented in 
official nginx docs (http://nginx.org/r/keepalive) as it 
might cause various problems.  It will likely be deprecated and 
removed.

Maxim Dounin