How I can find out which postgresql I am connected into when behind a load balancer?

Question

I have the following database replication setup:

As you can see I do a master-slave replication and I use aload balancer in order to connect into read-only replicas.

So I want to test this setup, hence I connect into my database into postgresql read-only replicas via Load Labalcer via psql command.

But how I can find out which replica I am connected into? I need that in order to perform a stress test.