Investigate Core DNS Support

[maleck13]

What

Some users, do not want to use public cloud provider DNS, have existing integrations with providers that we currently do not support or use their own "on prem" solutions. To support these type of users, we want to add support for integrating with core dns allowing use of DNSPolicy features and DNSRecord CRDs. The goal here is to offer parity via DNSPolicy using core dns to what we offer via cloud providers.

Identified Investigations

• resurrect @mikenairn script for installation
• Look at using DNSRecord as a backend for Core DNS (Custom DNS resource https://github.com/k8gb-io/coredns-crd-plugin)
• Understand how we can populate the DNS records for each individual Core DNS using DNS itself (https://www.k8gb.io/docs/images/k8gb-multi-cluster-interoperabililty.svg)
• Understand what the geo plugin offers and whether it suitable for our needs (https://coredns.io/plugins/geoip/)
• Understand what the load balancing plugin offers and if it is suitable for our needs (https://coredns.io/plugins/loadbalance/)
• Investigate whether locally we can resolve DNS from the local core dns

OutCome

• Understand what is possible and have a plan for DNS Policy with CoreDNS

Done

• Investigations identified
• Investigations completed and design and integration defined and shared to provide multi-cluster, geo weighted DNS