On Wed, Jun 9, 2010 at 8:55 AM, Rapsey <[email protected]> wrote:
> I use it to dispatch to another app. As for ordering, I think you would need
> to do it from the app if I understand your use case correctly.
>
>
> Sergej
It's true that X-Accel-Redirect would require this chaining logic in
your app. If this is truly unpalatable, then both nginx and varnish
have ways to put the chaining in the proxy.
nginx:
location /location1 {
proxy intercept errors on;
error_page 404 = @location1miss;
}
location @location1miss {
rewrite ^.*$ /location2
}
....etc
varnish:
vcl_recv {
if ($restarts == 0 ) {
set backend = backend0
} else if $(restarts == 1) {
set backend = backend1
} ....etc
}
vcl_fetch {
if (beresp.status == 404 && req.restarts <= N ) {
restart;
}
}
i like varnish's easy management of the number of chains, and i use
all three(haproxy, varnish, and nginx), but i end up using nginx's
named locations to handle unwanted backend responses to try various
backend's.
>
> On Wed, Jun 9, 2010 at 5:38 PM, Jonah Benton <[email protected]> wrote:
>>
>> Thanks for the rapid response. At first blush, X-Accel-Redirect
>> doesn't look to be quite what I need:
>>
>> * it appears that the specific use case is to dispatch to optimized
>> static file delivery; it's not clear whether the
>> dispatched-to-back-end can be another app, rather than something that
>> can be delivered with sendfile()
>> * assuming the dispatched-to-backend can be another app, can apps
>> arbitrarily chain themselves together with a series of
>> X-Accel-Redirect responses, or does nginx impose some sort of limit
>> * if apps can arbitrarily chain themselves together, this still means
>> I need to maintain the app ordering in the webapp rather than in the
>> proxy. The webapps are java, so this will be a little tricky, and the
>> chaining appears to have to be by path, which would be proxy-only
>> knowledge.
>>
>> So, maybe it's doable, though I'd rather be able to just maintain the
>> ordering in the proxy configuration.
>>
>> I'll look some more, though, thank you for the pointer.
>>
>> On Wed, Jun 9, 2010 at 2:58 AM, Rapsey <[email protected]> wrote:
>> > You can't do this with haproxy, but you can with nginx and
>> > X-Accel-Redirect
>> >
>> >
>> > Sergej
>> >
>> > On Wed, Jun 9, 2010 at 5:17 AM, Jonah Benton <[email protected]> wrote:
>> >>
>> >> Greetings,
>> >>
>> >> I have several web applications that each service different portions
>> >> of the same taxonomy. The taxonomy is very deep- millions of
>> >> resources- and the rules that dictate which part of the taxonomy each
>> >> application serves are fluid and changing. In general it isn't easy to
>> >> determine declaratively which web application should service which
>> >> uri.
>> >>
>> >> I'd like to set up a proxy dispatch hierarchy, such that requests
>> >> arriving at a proxy front end would be dispatched to one of the web
>> >> applications. The response from web application 1 would checked by the
>> >> proxy front end. If it's a 404, then the front end discards the
>> >> response from web application 1, and dispatches to the next web
>> >> application. If non-404, then the response is returned to the client
>> >> and the transaction is considered handled. A 404 response from the
>> >> last web application would be considered a true 404 and would get
>> >> returned to the client.
>> >>
>> >> From a quick look at the configuration, it doesn't appear that this
>> >> can be done with HAProxy (nor with any other proxy software I've
>> >> looked at). Am I wrong, can this be arranged?
>> >>
>> >> Please cc me, I'm not subscribed to the list.
>> >>
>> >> Thank you,
>> >>
>> >> Jonah
>> >>
>> >
>> >
>
>
