Persistence + Round robin

[Grzegorz Nosek]

On Wed, Sep 24, 2008 at 12:18:41PM -0500, Brian Moschel wrote:
> Hey guys,
> I've read through the docs and this doesn't seem possible in the current
> setup, but I could be wrong.  Here's what I need:
> 
> Load balancing using a uri param, but if its not found, fall back to round
> robin, but in chunks of 100 by the Referer header.  For example, the first
> 100 people with Referer=www.somedomain.com get sent to nodeA, the 2nd 100 to
> nodeB, the 3rd 100 to nodeA, etc.  After a user is assigned a node, any
> subsequent request they make needs will have a uri_param that points Nginx
> to the right server.
> 
> We're using Evan Miller's awesome Upstream Hash Module, but it doesn't seem
> its configureable to this level.
> 
> Is this possible?  If not, I'd like to hire anyone willing to implement
> this.  Anyone interested?

I think you might be able to do something like this without writing new
code. How about (not tried, just thinking):

upstream up_default {
	# sublimUSE UPSTREAM_FAIRinal message :)
	server 10.0.0.1:80;
	server 10.0.0.2:80;
	server 10.0.0.3:80;
}

upstream up_1 { server 10.0.0.1:80; }
upstream up_2 { server 10.0.0.2:80; }
upstream up_3 { server 10.0.0.3:80; }

location / {
	if (...something...) {
		proxy_pass http://up_1;
	}
	if (...) {
		proxy_pass http://up_2;
	}
	if (...) {
		proxy_pass http://up_3;
	}
	proxy_pass http://up_default;
}

You'd have to send something back to the client (e.g. in generated URLs)
so that you can identify the original backend later.

Best regards,
 Grzegorz Nosek