Add readme for coredns

[pacoxu]

What this PR does / why we need it:
No readme for coredns, only some for kube-dns

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:
add some links and descriptions like kube-dns

Release note:

NONE

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[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: pacoxu
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[pacoxu]

CLA registered

[MrHohn]

/assign @rajansandeep
I think it would be more clear if we keep coredns and kube-dns manifests in separate folders (e.g. dns/coredns, dns/kube-dns), though that requires changing cluster-up scripts.

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@MrHohn: GitHub didn't allow me to assign the following users: rajansandeep.

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In response to this:

/assign @rajansandeep
I think it would be more clear if we keep coredns and kube-dns manifests in separate folders (e.g. dns/coredns, dns/kube-dns), though that requires changing cluster-up scripts.

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[MrHohn]

/ok-to-test

[rajansandeep]

@MrHohn Yes, keeping them in different folders is doable. Is this something we need to prioritize for 1.10 or it can be for later releases?

[rajansandeep]

This guide applies to installing CoreDNS via kubeadm and doesn't apply here.

[neolit123]

@rajansandeep i agree.
also given the ongoing transition to CoreDNS the above paragraph would be misleading for the next release. i would Close this PR, until we have settled.

[MrHohn]

@rajansandeep No worries, seems fine to do that for later releases.

[fejta-bot]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale.
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/lifecycle stale

[neolit123]

/remove-lifecycle stale

@rajansandeep @MrHohn

hello, how do you want to proceed with this PR?

@pacoxu
given there are a couple of folders now under cluster/addons/dns/
the name of the file should not be coredns_README.md, but rather it should go as README.md in here:
https://github.com/kubernetes/kubernetes/tree/master/cluster/addons/dns/coredns

[neolit123]

@pacoxu also please sign the CLA.
instructions in the second comment.

[chrisohaver]

FYI, cluster/addons per the Kubernetes docs has been described as "deprecated" for quite some time now.

From https://kubernetes.io/docs/concepts/cluster-administration/addons/ :

There are several other add-ons documented in the deprecated cluster/addons directory.
Well-maintained ones should be linked to here. PRs welcome!

I believe "here" above refers to the addons docs page itself, not the deprecated cluster/addons directory.

IMO, if the docs are wrong, they should be fixed.
If they are right, then we should mention that cluster/addons is deprecated in it's README. Something like this ...

This directory is deprecated, please link well maintained add-ons to the Addons section in the Kubernetes Documentation.

i.e. the reciprocal of the message in the docs.

[neolit123]

@chrisohaver hm, i don't know if the docs are wrong in this case.
possibly the CoreDNS team should decide and action some new PRs here.

this particular PR might not get any further updates from the original author.
so let me know if you want me to close it.

[chrisohaver]

I say close it. Per my understanding this addons directory is supposed to be deprecated (as of 10 months ago), and is also titled "Legacy Addons".

[neolit123]

I say close it. Per my understanding this addons directory is supposed to be deprecated (as of 10 months ago), and is also titled "Legacy Addons".

ok

/close