I originally built node-monitor (https://github.com/franklovecchio/node-monitor/tree/v0.5) to monitor multiple servers; I was trying to emulate Splunk by sending all data from an environment to a couple servers, which then pushed out to websockets (live log viewing) + POSTed to CloudWatch. Ended up throwing out the socket piece because it was a pain in the ass to manage.

On a side note, you can scale what would be single-instance architecture with something like messenger (think an MQtt.js broker).