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Re: Proxy Retry Logic

December 22, 2010 08:20PM
Hi,

On 22/12/2010 21:26, Sirsiwal, Umesh wrote:
>
> All,
>
> I am trying to write a module which uses a number of subrequests to
> talk to backend servers. Combines the responses and sends them back to
> the client. The communication with the backend server is using HTTP
> and I am using proxy_pass for that.
>
> The peculiarity in our setup is that on failure-retry I need to use a
> different URI than the original request. Current, proxy reinit request
> does not regenerate request hence cannot be used for the purpose. I
> tried using the error_page in the subrequest location to point to a
> different location. But, it seems that the error_page is not evaluated
> on subrequest. The only option I can think of is for my module to
> detect error and issue a new subrequest.
>
> Is this the best solution for this problem? Will that affect
> subrequest response concatenation?
>
I think you can do this now using the echo module
(http://wiki.nginx.org/HttpEchoModule), subrequests and try_files

e.g.

location /main {
echo_location /sub1; # could also be echo_location_async
echo_location /sub2; # (ditto)
}

location /sub1 {
try_files ...
}

location /sub 2 {
try_files ...
}

Where ... in try_files are the separate proxy locations.

I'm not certain (and I've not tested / looked at the code) what happens
when a proxied request returns a non-200 response, but I am assuming
that try_files tries the next location on the list. If it does (and it
should if it doesn't), and you know the URL of the new testing location,
then this method should work.

A word of caution about using both synchronous and asynchronous echo_
commands next to one another. There used to be (and I'm not sure if
they've been fixed yet or not) issues with this. Use either sync or
async combined and you should be fine (async is probably a better
option, since it's likely to give a faster response to the client in
this case).

Cheers,

Marcus.
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Subject Author Views Posted

Proxy Retry Logic

Sirsiwal, Umesh 2508 December 22, 2010 02:28PM

Re: Proxy Retry Logic

Maxim Dounin 959 December 22, 2010 06:40PM

RE: Proxy Retry Logic

Sirsiwal, Umesh 1046 December 22, 2010 07:56PM

Re: Proxy Retry Logic

Eugaia 970 December 22, 2010 08:20PM

RE: Proxy Retry Logic

Sirsiwal, Umesh 1017 December 22, 2010 08:52PM

Re: Proxy Retry Logic

Eugaia 1072 December 22, 2010 09:10PM

RE: Proxy Retry Logic

Sirsiwal, Umesh 884 December 22, 2010 09:26PM

Re: Proxy Retry Logic

Eugaia 951 December 22, 2010 09:38PM

RE: Proxy Retry Logic

Sirsiwal, Umesh 962 December 22, 2010 09:52PM

Re: Proxy Retry Logic

Eugaia 1189 December 23, 2010 04:00AM

Re: Proxy Retry Logic

Eugaia 1026 December 23, 2010 04:36AM

RE: Proxy Retry Logic

Sirsiwal, Umesh 1211 December 23, 2010 08:12AM

Re: Proxy Retry Logic

Eugaia 910 December 22, 2010 09:22PM



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