Merge pull request #2167 from rajansandeep/corednsdefault

KEP for CoreDNS to Default DNS

keps/NEXT_KEP_NUMBER

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keps/sig-network/0012-20180518-coredns-default-proposal.md

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+---
+kep-number: 11
+title: Switch CoreDNS to the default DNS
+authors:
+  - "@johnbelamaric"
+  - "@rajansandeep"
+owning-sig: sig-network
+participating-sigs:
+  - sig-cluster-lifecycle
+reviewers:
+  - "@bowei"
+  - "@thockin"
+approvers:
+  - "@thockin"
+editor: "@rajansandeep"
+creation-date: 2018-05-18
+last-updated: 2018-05-18
+status: provisional
+---
+
+# Switch CoreDNS to the default DNS
+
+## Table of Contents
+
+* [Summary](#summary)
+* [Goals](#goals)
+* [Proposal](#proposal)
+    * [User Cases](#use-cases)
+* [Graduation Criteria](#graduation-criteria)
+* [Implementation History](#implementation-history)
+
+## Summary
+
+CoreDNS is now well-established in Kubernetes as the DNS service, with CoreDNS starting as an alpha feature from Kubernetes v1.9 to now being GA in v1.11.
+After successfully implementing the road-map defined [here](https://github.com/kubernetes/features/issues/427), CoreDNS is GA in Kubernetes v1.11, which can be installed as an alternate to kube-dns in tools like kubeadm, kops, minikube and kube-up.
+Following the [KEP to graduate CoreDNS to GA](https://github.com/kubernetes/community/pull/1956), the purpose of this proposal is to make CoreDNS as the default DNS for Kubernetes, replacing kube-dns.
+
+## Goals
+* Make CoreDNS the default DNS for Kubernetes for all the remaining install tools (kube-up, kops, minikube).
+* Make CoreDNS available as an image in a Kubernetes repository (To Be Defined) and ensure a workflow/process to update the CoreDNS versions in the future.
+  This goal is carried over from the [previous KEP](https://github.com/kubernetes/community/pull/1956), in case it cannot be completed there.
+
+## Proposal
+
+The proposed solution is to enable CoreDNS as the default cluster service discovery DNS for Kubernetes.
+Some of the most used deployment tools will be upgraded by the CoreDNS team, in cooperation with the owners of these tools, to be able to deploy CoreDNS as default:
+* kubeadm (already done for Kubernetes v1.11)
+* kube-up
+* minikube
+* kops
+
+For other tools, each maintainer would have to add the upgrade to CoreDNS.
+
+### Use Cases
+
+Use cases for CoreDNS has been well defined in the [previous KEP](https://github.com/kubernetes/community/pull/1956).
+The following can be expected when CoreDNS is made the default DNS.
+
+#### Kubeadm
+
+* CoreDNS is already the default DNS from Kubernetes v1.11 and shall continue be the default DNS.
+* In case users want to install kube-dns instead of CoreDNS, they have to set the feature-gate of CoreDNS to false. `--feature-gates=CoreDNS=false`
+
+#### Kube-up
+
+* CoreDNS will now become the default DNS.
+* To install kube-dns in place of CoreDNS, set the environment variable `CLUSTER_DNS_CORE_DNS` to `false`.
+
+#### Minikube
+
+* CoreDNS to be enabled by default in the add-on manager, with kube-dns disabled by default.
+
+#### Kops
+
+* CoreDNS will now become the default DNS.
+
+## Graduation Criteria
+
+* Add CoreDNS image in a Kubernetes repository (To Be Defined) and ensure a workflow/process to update the CoreDNS versions in the future.
+* Have a certain number (To Be Defined) of clusters of significant size (To Be Defined) adopting and running CoreDNS as their default DNS.
+
+## Implementation History
+
+* 20170912 - [Feature proposal](https://github.com/kubernetes/features/issues/427) for CoreDNS to be implemented as the default DNS in Kubernetes.
+* 20171108 - Successfully released [CoreDNS as an Alpha feature-gate in Kubernetes v1.9](https://github.com/kubernetes/kubernetes/pull/52501).
+* 20180226 - CoreDNS graduation to Incubation in CNCF.
+* 20180305 - Support for Kube-dns configmap translation and move up [CoreDNS to Beta](https://github.com/kubernetes/kubernetes/pull/58828) for Kubernetes v1.10.
+* 20180515 - CoreDNS was added as [GA and the default DNS in kubeadm](https://github.com/kubernetes/kubernetes/pull/63509) for Kubernetes v1.11.