Handler invokation after upstream server being picked

[Maxim Dounin]

Hello!

On Fri, Oct 25, 2013 at 12:30:34PM +0200, Jan Algermissen wrote:

> Hi,
> 
> I am writing a module that needs to add/change the HTTP 
> Authorization server for an upstream request.
> 
> Since I am using a signature based authentication scheme where 
> the signature base string includes the request host and port the 
> header can only be added *after* the upstream module has 
> determined which server to send the request to (e.g. after 
> applying round-robin).
> 
> Is it possible to hook my module into that 'phase' and if so - 
> what is the preferred way to do that?
> 
> I saw that I at least can access the target host and port set by 
> the proxy module by reading the proxy module variables. However, 
> that (of course) does only give the server group name to be used 
> by the upstream module in the next step.

A request to an upstream is created once, before a particular 
server is known, and the same request is used for requests to all 
upstream servers.  That is, what you are trying to do isn't 
something currently possible.

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