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Update CoreDNS docs for beta #7638

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Mar 5, 2018
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Update CoreDNS docs for beta #7638

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Update CoreDNS docs for beta
johnbelamaric Mar 5, 2018
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johnbelamaric Mar 5, 2018
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22 changes: 19 additions & 3 deletions docs/tasks/administer-cluster/coredns.md
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Expand Up @@ -5,7 +5,7 @@ title: Using CoreDNS for Service Discovery
min-kubernetes-server-version: v1.9
---

{% include feature-state-alpha.md %}
{% include feature-state-beta.md %}

{% capture overview %}
This page describes how to enable CoreDNS instead of kube-dns for service
Expand All @@ -20,15 +20,31 @@ discovery.

## Installing CoreDNS with kubeadm

In Kubernetes 1.9, [CoreDNS](https://coredns.io) is available as an alpha feature and
may be installed by setting the `CoreDNS` feature gate to `true` during `kubeadm init`:
In Kubernetes 1.9, [CoreDNS](https://coredns.io) is available as an alpha feature, and
in Kubernetes 1.10 it is available as a beta feature. In either case, you may install
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If this is beta in 1.10, should we set the default of this feature gate to be true? cc @luxas

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Question was raised during one of the Network SIG, and the decision was that CoreDNS will be default when going GA. That means for v1.11.

NOTE: I think that before releasing with CoreDNS as default, it would be good to see the impact of this change against all the e2e tests that are based on kubeadm.

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Exactly. Unlike beta features that are driven by the API and therefore only in effect if the user accesses that API, this feature replaces an existing component when enabled. So, defaulting it to true would be essentially promoting it to GA.

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This makes sense. Totally agreed. 👍

it during cluster creation by setting the `CoreDNS` feature gate to `true` during `kubeadm init`:

```
kubeadm init --feature-gates=CoreDNS=true
```

This installs CoreDNS instead of kube-dns.

## Upgrading an Existing Cluster with kubeadm

In Kubernetes 1.10, you can also move to CoreDNS when you use `kubeadm` to upgrade
a cluster that is using `kube-dns`. In this case, `kubeadm` will generate the CoreDNS configuration
("Corefile") based upon the `kube-dns` ConfigMap, preserving configurations for federation,
stub domains, and upstream name server.

Note that if you are running CoreDNS in your cluster already, prior to upgrade, your existing Corefile will be
**overwritten** by the one created during upgrade. **You should save your existing ConfigMap
if you have customized it.** You may re-apply your customizations after the new ConfigMap is
up and running.

This process will be modified for the GA release of this feature, such that an existing
Corefile will not be overwritten.

{% endcapture %}

{% capture whatsnext %}
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