Requirements for using the Cloud SQL Auth proxy

Requirements for using the Cloud SQL Auth proxy
To use the Cloud SQL Auth proxy, you must meet the following requirements:

The Cloud SQL Admin API must be enabled.
You must provide the Cloud SQL Auth proxy with Google Cloud authentication credentials.
You must provide the Cloud SQL Auth proxy with a valid database user account and password.
The instance must either have a public IPv4 address, or be configured to use private IP.

The public IP address does not need to be accessible to any external address (it does not need to be added as an authorized network address).