reroute to different backend on 404 ?

Hi,

I'm not quite sure if this is possible with HAproxy, I could do it with nginx, but I'd like to utilize HAproxy's logging to monitor it.

We have a "new" document location, and an "old" document location, and we are migrating the documents from the old location to the new..

While we are performing this migration from the old to the new, I want to make sure that it is as seamless as possible to the client libraries.

I was thinking something along the lines of:

    frontend docs

        acl new_repo hdr_beg(host) -i docs.example.com
        acl old_repo hdr_beg(host) -i docs-old.example.com

        use_backend new_repo if new_repo
        use_backend old_repo if old_repo

        default_backend new_repo

    backend new_repo
        server new1 10.10.42.1:80

    backend old_repo
        server old1 10.10.43.1:80

Ideally, what I would like, is if the response from the new_repo backend is a 404, it should redispatch internally to the old_repo backend.

If that is not possible, then I could make do with the 404 response from the new_repo backend being converted to a 302 response to the client libs with a Location header specifying a different hostname, but the same path.

Thoughts?

enjoy,

-jeremy

--

 Jeremy Hinegardner                              jeremy#hinegardner.org