Using observer triggered functions with cluster

1

How can I make sure an observer-triggered function is only called once on an app that uses cluster to load balance multiple instances of the app?

edit: before anyone mentions making a new micro-service to handle the observer in a standalone app, it just really doesn’t fit our domain model and our codebase is getting too big to make sacrifices like that

2

Who first insert record to collection, that instance will have right to handle it :smiley:
Using mongo as token distributor for example.