Google just posted a blog[0] about multi-region clusters and ingress.

It's a little hacky as you need to create multiple clusters in each zone/region and then with an anycast IP attached to a Google Cloud Load Balancer.

[0] https://cloudplatform.googleblog.com/2018/06/How-to-deploy-g...

Hacky is not production ready.

Its not hacky in that sense. They provide a new kubemci tool and I'm sure it will be given the k8 release treatment.