How do I set up a scalable architecture?

Hi,

I’d like to have tips about a big wep app upcoming deployment in the cloud. I’m trying to move this app from my on-premise servers to the Digital Ocean cloud.

My app is written in Node.js. Occasionally like 2days/year I need to scale to deal with traffic increase.

My app uses clustering techniques to spawn more workers and take advantage of the multi-core architecture.

Now, my idea is to have a little server serving 365days per year this app, and spend as less as possible. And occasionally be able to automatically scale up (horizontally) to serve over 200 request per second and of course I’ll pay for that single day intensive usage. My load balancer is written in node.js with the node-http-proxy module. How do I monitor the Droplet CPU/Memory usage? How do I launch a new Droplet with my software already installed (clone?) ?

I Hope I was as clear as possible.

Let me know, any tip is appreciated.