dynamic proxy_pass?

[Petite Abeille]

Hello,

[nginx 0.6.32]

I would like to setup a dynamic proxy_pass. More specifically, given  
an HTTP request's authorization header, I would like to proxy the  
request to a specific upstream server.

For example, given a cdb [1] of 'user' -> 'server', upon receiving a  
request, dispatch a given user to a given server.

What would be a reasonable way to achieve such effect with nginx?

Thanks in advance for any pointers.

Kind regards,

--
PA.
http://alt.textdrive.com/nanoki/

[1] http://cr.yp.to/cdb.html