Cloud NAT Gateway enables inbound and outbound connections over the Internet, for your virtual servers that have only private IP addresses.
The servers access the Internet by routing the traffic through the NAT gateway. Optionally, the servers can receive inbound connections from the Internet using the port forwarding feature.
This solution helps you avoid costs for public IPs, but even more than that. It enables backend applications to access the Internet, as well as public access to your web apps placed behind NAT.