Feature request: redispatch-on-5xx

[Dmitry Sivachenko]

Hello!

One more thing which can be very useful in some setups: if backend server 
returns HTTP 5xx status code, it would be nice to have an ability to retry the 
same request on another server before reporting error to client (when you know 
for sure the same request can be sent multiple times without side effects).

Is it possible to make some configuration switch to allow such retries?

Thanks.

Re: Feature request: redispatch-on-5xx

[Willy Tarreau]

Hi Dmitry,

On Mon, Jun 23, 2014 at 06:16:28PM +0400, Dmitry Sivachenko wrote:
 Hello!
 
 One more thing which can be very useful in some setups: if backend server
 returns HTTP 5xx status code, it would be nice to have an ability to retry
 the same request on another server before reporting error to client (when you
 know for sure the same request can be sent multiple times without side
 effects).
 
 Is it possible to make some configuration switch to allow such retries?

No it is not because if the server has responded, it means that haproxy does
not have the request anymore. That's precisely one of the difficulties of
implementing server-side multiplexing.

Willy