How do I decide if I need to introduce HAProxy into my nginx-unicorn stack for my web application?

Question

I'm building a service-based web application. It consists of one primary rails app purely meant to handle requests, and a lot of other sinatra services running to actually process these requests.

I've decided to go with unicorn for the actual webserver for my rails app.

My dilemma is in picking the right stack to go with. I've read some great reviews about HAProxy's load balancing and I think that is the way to go for the long term. On the other hand, some people I know are also saying nginx would be good enough when I use it with unicorn.

At the moment, my entire system is going to reside on a single server. In the future, different servers might host different services.

Would I be introducing unnecessary overhead by introducing haproxy? How would I really gain from using HAproxy along with nginx?

Answer 1

Yep, haproxy's completely unnecessary. Unicorn does it's own "load balancing" between it's workers. When you move to needing multiple machines, you can use haproxy, but I strongly prefer an L3 solution such as IPVS.