"first" load balancing

[KT Walrus]

The purpose of this message is to request a new feature be added to NGINX - "first" load balancing algorithm and MAXCONN setting for upstream servers.

I am setting up a new site that will require multiple upstream servers and load balancing.  I plan to use ip_hash load balancing on frontend servers to do simple load balancing to the backend servers.  I would like to protect each backend server from becoming overloaded and possibly failing because of too many connections sent to it.

I plan on using haproxy to "guard" each backend server by using haproxy's "first" load balancing and setting a MAXCONN for the localhost backend.  If the maximum connections for the server is met, haproxy will send the request to the next server in the list.  I also plan on using Amazon EC2 instances and this set up will not only protect each backend server from becoming overloaded, it allows me to "spin up" new backend servers if the last backend server is approaching MAXCONN.  Similarly, if the last two backends in my server farm are not receiving any requests, I can "spin down" the last server (and save me money!!!).

Now, it seems to me I could remove haproxy from my server software stack if NGINX added support for "first" load balancing and MAXCONN setting for each upstream server.  I think this should be relatively easy to support since I see NGINX already supports "least conn" load balancing.  I guess this means that NGINX already knows how many connections it has open to an upstream server and could easily implement "first" and "max conn".

Kevin