I'm facing a similar issue. According to
this blog post from GCP it seems like I should be able to connect to the Private IP of a Cloud SQL instance simply by creating a service and endpoint however I am not able to connect to the service via the Kubernetes Service Name <svc-name>.<namespace>.svc.cluster.local. With `dig` in a container on my cluster that DNS resolves to the correct private IP but I cannot connect. I have one deployment in my cluster which uses `hostNetwork: true` and I can connect with no problem from inside that container, but I need to be able to connect from a container that does not use the host network.
I understand that enabling Alias IPs may be what is needed, but do not currently have a cluster with that enabled and I would rather not recreate the whole cluster if I can help it. Does the blog post assume that Alias IPs is enabled already or am I missing something? So far I have not tried using a NAT gateway or proxy. Thanks