limit proxy_next_upstream

[Maxim Dounin]

Hello!

On Fri, Apr 05, 2013 at 09:59:29PM +0800, Weibin Yao wrote:

> We have the similar request. If we have dozens of servers in a same
> upstream block, I don't want to retry all of them. One side effect is it
> will increase the failure count with all of the backend servers. After
> several times, all of the servers will be marked down for a while and all
> of the requests will be replied with 502.
> 
> We also need the retry mechnism and don't want to diable it. I think if
> there is a configurable tries time with the direcitve proxy_next_upstream,
> it will be very nice.

This is somewhere in TODO, and likely will be implemented soon.  
As usual, the most serious problem is a name for the directive 
(proxy_next_tries?).  :)

Additional similar proposal discussed here includes limiting total 
time spent in retries before giving up (proxy_next_time?).  This 
will allow to try many servers as soon as they, e.g., return RST 
quickly, but to only try one or two servers if they fail to answer 
in configured proxy_connect_timeout/proxy_read_timeout.

> 
> 
> 2013/4/5 Maxim Dounin <mdounin at mdounin.ru>
> 
> > Hello!
> >
> > On Fri, Apr 05, 2013 at 04:38:36AM -0400, philipp wrote:
> >
> > > Is it possible to limit the amount of upstreams asked? I have four
> > upstreams
> > > defined and it makes no sense to ask all of them. If two of them timeout
> > or
> > > error there is possible something wrong with the request and asking
> > another
> > > node doesn't help.
> >
> > No, as of now only switching off proxy_next_upstream completely is
> > available.
> >
> > On the other hand, with switched of proxy_next_upstream you may
> > still configure retries to additional (or other) upstream servers
> > via error_page directive, using a configuration similar to last
> > example at http://nginx.org/r/error_page.
> >
> > Something like this should generate no more than two requests
> > regardless of number of upstream servers configured:
> >
> >     location / {
> >         error_page 502 504 = @fallback;
> >         proxy_pass http://backend;
> >         proxy_next_upstream off;
> >     }
> >
> >     location @fallback {
> >         proxy_pass http://backend;
> >         proxy_next_upstream off;
> >     }
> >
> > --
> > Maxim Dounin
> > http://nginx.org/en/donation.html
> >
> > _______________________________________________
> > nginx mailing list
> > nginx at nginx.org
> > http://mailman.nginx.org/mailman/listinfo/nginx
> >
> 
> 
> 
> -- 
> Weibin Yao
> Developer @ Server Platform Team of Taobao

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-- 
Maxim Dounin
http://nginx.org/en/donation.html