Can I use Amazon ELB instead of nginx as load balancer for my Node.Js app?

Question

I have a Node.js app and I've seen a lot of posts here in SO that it needs to be behind a nginx as load balancer. Since I'm already accustomed to Amazon's services, thus my question.

Answer 1

Yes, but there are a few gotcha to keep in mind:

1. If you have a single server, ensure you don't return anything except 200 to the page that ELB uses to check health. We had a 301 from our non-www to www site, and that made ELB not send anything to our server because of it.

2. You'll get the ELB's IP instead of the client's in your logs. There is an ngx_real_ip module, but it takes from config hacking to get it to work.

Answer 2

ELB works great in front of a basic Node.js application. If you want WebSockets, you need to configure it for TCP balancing. TCP balancing doesn't support sticky sessions though, so you get one or the other.