On Sat, Mar 31, 2012 at 7:55 PM, Kevin Heatwole <ke...@heatwoles.us> wrote: > I am just investigating use of haproxy for the first time. > > I'd like the balancing algorithm to send http request to the first server in > the list until the number of requests hits a configurable number. When the > request limit for a server is hit, I then want new requests to go to the next > server until that server hits its configurable limit. So, instead of RR, I > want to load down a server before overflowing to the next server. > > What I think I want to do is to always have the last server in the farm not > have any requests. If it does, I will activate another server to ensure I > have enough capacity to handle the load spike. But, when the last two > servers go completely idle again, I can deactivate the last idle server. > > My servers are "in the cloud" and I pay for each one that is activated so I > think this type of load balancing would help me activate only servers I need > (saving me money). > > I would plan to automate this by having all servers included in the haproxy > config but only the first server would initially be UP and all others DOWN. > When a server handles a request, it makes sure that its next server is > activated. When a server doesn't handle any requests for some time, it > deactivates its next server (if any).
You could implement this by monitoring your available slots on a backend, once the slots decrease %N of total slots, spin up new instances. Apply the same logic in reverse to turn off nodes. I presume you can hardcode IP addresses ahead of time? > > Does this make sense? I'm new to scaling out and haproxy, so if this scheme > already exists, please point me to where it is discussed in the documentation. > > Kevin
