upstream and address resolution

Maxim Dounin mdounin at
Sun Jul 20 23:43:59 MSD 2008


On Sun, Jul 20, 2008 at 06:51:14PM +0200, Manlio Perillo wrote:

> On a server using Nginx 0.5.x I have noted that, when one of the  
> upstream servers changed the IP address, the old address was still used.
> I have restarted Nginx and solved the problem, but I'm not sure to  
> understand what happened.

Nginx does name resolution only at startup/reconfiguration (unless 
you use variables in proxy_pass, as introduced in 0.6.18, but it's 
very special case).

I'm not sure if it's documented somewhere, but it's how it works 
since creation.  I don't think this will be ever changed - since 
you generally don't want to stress your DNS subsystem (and depend 
on it) under high load.  Just don't forget kill -HUP when you 
change ip's.

Maxim Dounin

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