Help with chaining of sub-requests

agentzh agentzh at
Tue Apr 17 07:19:56 UTC 2012

On Tue, Apr 17, 2012 at 5:51 AM, Ashish S < at> wrote:
> I have 3 existing http backend web-services  S1, S2 and S3.  I am
> trying to use nginx for a use-case where  i need to first get a "key"
> from service S1, use this key along with some input data, to query S2,
> and based on S2's response, query S3.    My question is, would
> sub-request chaining be the best method to go about this?  I can use
> the upstream method to connect to S1.   Am i doing something wrong, if
> I then fire a sub-request (request to S2) from within the content
> handler (process header) method registered for this upstream?.  How do
> i then initiate the sub-request to S3 ?
> Any pointers or example that i might be able to follow, for something
> like the above?

Regarding chained subrequest implementation, see ngx_echo module's
echo_subrequest directive for an example:

Also ngx_lua's ngx.location.capture() and ngx.location.capture_multi()
worth a look too:

Regarding non-subrequest upstream communication, ngx_lua supports the
cosocket API which implements something similar to (but more general
than) ngx_http_upstream:

Hope these helps,

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