There are also a few wrappers around cluster to make orchestration and mgt easier[1].
It's also worth looking at the new Worker Threads API[2] for node. If you're spinning off for compute intensive things, wrapping worker threads in a pool is a pretty good option.
NOTE: If you are using Kubernetes, do *NOT* use clustering in node. You're better off using the external management of k8s and launching multiple instances that way. It'll simplify your management and communications interfaces.
[1] https://www.npmjs.com/package/cluster-service
[2] https://nodejs.org/api/worker_threads.html