Cloud Run to Cloud SQL UNIX socket connections: Does it use private or public IP?

Question about Cloud RUN connections to Cloud SQL. If i were to use UNIX socket based connections does it use the private IP or the public IP of the Cloud SQL instance can’t tell from this repo|link. Private IP is preferred option for obvious reasons hence want to use Private IP

By default cloud sql auth proxy should try the public IP for the instance. If you are using version 1.x.x of the proxy. then you need to use -ip_address_types=PRIVATE as the option. If you use version 2.x.x then the option would be --private-ip. It seems in the example from the link it is still the version 1.x.x of the proxy.

Yes i can recall now thanks so much.