Enable CoreDNS as a DNS plugin for Kubernetes

[johnbelamaric]

Feature Description

• One-line feature description (can be used as a release note): Enable CoreDNS as a DNS plugin for Kubernetes
• Primary contact (assignee): @johnbelamaric
• Responsible SIGs: sig-network, sig-cluster-lifecycle
• Design proposal link (community repo): Add coredns proposal community#1100
• Reviewer(s) - (for LGTM) recommend having 2+ reviewers (at least one from code-area OWNERS file) agreed to review. Reviewers from multiple companies preferred: @bowei @thockin
• Approver (likely from SIG/area to which feature belongs): @thockin
• Feature target (which target equals to which milestone):
  • Alpha release target (1.9)
  • Beta release target (1.10)
  • Stable release target (1.11)

[johnbelamaric]

cc @luxas @jbeda @mattmoyer @miekg

[cmluciano]

@kubernetes/sig-network-feature-requests

[klausenbusk]

What is the argument behind this switch?

[johnbelamaric]

Hi Kristian,

Here's a little background. CoreDNS is another CNCF project and is the successor to SkyDNS, which kube-dns is based on. It is a flexible, extensible authoritative DNS server and we have built a direct integration to the Kubernetes API. It can serve as cluster DNS, complying with the dns spec. We started discussions with @thockin, @matchstick and @bowei last year around KubeCon and they are open to it in principle, but of course it needs to be proven to be the right choice.

As for reasons to switch, CoreDNS has fewer moving parts than kube-dns, since it is a single executable and single process. It is written in Go so it is memory-safe (kube-dns includes dnsmasq which is not). It supports a number of use cases that kube-dns doesn't. As a general-purpose authoritative DNS server it has a lot of functionality that kube-dns couldn't reasonably be expected to add.

You may also want to check out the intro or coredns.io. There is also a webinar I did for CNCF a couple months back.

[smarterclayton]

I would expect a proposal for this.

[johnbelamaric]

Ok, will do. I assume that means based on https://github.com/kubernetes/community/blob/master/contributors/design-proposals/Design_Proposal_TEMPLATE.md