How to gracefully shut down or remove AWS instances from an ELB group
I have a cloud of server instances running at Amazon using their load balancer to distribute the traffic. Now I am looking for a good way to gracefully scale the network down, without causing connection errors on the browser's side.
As far as I know, any connections of an instance will be rudely terminated when removed from the load balancer.
I would like to have a way to inform my instance like one minute before it gets shut down or to have the load balancer stop sending traffic to the dying instance, but without terminating existing connections to it.
My app is node.js based running on Ubuntu. I also have some special software running on it, so I prefer not to use the many PAAS offering node.js hosting.
Thanks for any hints.
Answer
I know this is an old question, but it should be noted that Amazon has recently added support for connection draining, which means that when an instance is removed from the loadbalancer, the instance will complete requests that were in progress before the instance was removed from the loadbalancer. No new requests will be routed to the instance that was removed. You can also supply a timeout for these requests, meaning any requests that run longer than the timeout window will be terminated after all.
To enable this behaviour, go to the Instances tab of your loadbalancer and change the Connection Draining behaviour.