I have read Mongo Docs and some posts, but it's not clear enough to me. I don't understand how it works when Mongo is distributed on different hosts
I want to develop a cluster with replica sets (so an app can stand network and database issues) on different hosts (EC2 instances). Let's assume this scenario (based on this tutorial ):
Instance A: Primary node on 10.0.0.1
Instance B: Secondary node on 10.0.0.2
Instance C: Arbiter on 10.0.0.3
My app is working normal and is connected to A (the IP 10.0.0.1 is configured as an environment variable). Suddenly Mongo inside A crashes due to any reason, then Mongo does its stuff, and C chooses B as the new Primary. What will happen with my app that is connected to A? Does Mongo redirect to B automatically? What happens when the whole instance (A) is down? Do I need to add some additional code to handle this?
I have been working only with single mongo instance, but this time I want to do something bigger and more consistent, and this confuses me. I appreciate your answers.