Postgresql AutoFailover

I am having Java Application with Two nods in cluster however I have Postgresql 1 Master Database server and 3 nodes in Hot-Standby Mode.

Problem: Since DB is a single point of failure, every time patching the servers I need to bring down the entire Application which increases my Application downtime.

Looking for a Solution to implement Postgres DB Autofailover to Stand By node. My Environment: Ubuntu 18 OS with Postgres v10

Questions:

  1. Postgres 10 Supports Auto Failover?
  2. is it possible to implement AutoFailover of DB using Postgres native tools?
  3. I am planning to configure my application to point to single LB IP which is configured to connect to an active DB server out of 4 Postgres DB serves( Out of 4 one is master). Any recommendation on this is welcome.
  4. How to configure Auto failover for Postgresql DB with minimal failover time?