Dynamic configuration updates?

Hi all,

We're moving to a system where each of our customers will have a separate xen server with just that customer's data and an instance of the webapplication in it (multiple users/customer). Now we have the issue of routing user sessions to the appropriate backend server after they have authenticated.

Assume that login/authentication will happen in a separate gateway application and that when authenticated, the login app will populate a lookup table with the user's session id as the key and the value is the 10.x.x.x address of the customer's xen instance.

What I would like to do is have HAproxy, or something, be able to check the Cookie: header, extract the session id, lookup that session id in the lookup table and route the request to the appropriate IP address.

This also means that when we provision a new xen slice for a customer, that results in a new backend.

So far, nothing I have found is able to do something along these lines. It looks to me like I'll have to do some sort of customization to HAproxy, nginx or varnish to get the functionality that I'm looking for.

If I boil it down to HAproxy terms, I would want to have a single frontend with dynamically create acls based upon data looked up in a table written to by some other process. Then those acls would be used to route HTTP traffic to backends, most likely dynamically created.

I have considered just generating a haproxy config with all the backends necessary, but that does not help with mapping the session id's to the backends at runtime.

Thoughts? Am I just crazy thinking of this?

enjoy,

-jeremy

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 Jeremy Hinegardner                              jeremy#hinegardner.org