fix(addons/coredns.addons.k8s.io) Workaound to stop coredns crashing on 1.3.1 version

[phspagiari]

There is a known bug on CoreOS 1.3.1 wherein if the Kubernetes API shuts down while CoreDNS is connected, CoreDNS will crash.

The workaround is to create a /tmp volume See here

Logs:

E0827 00:44:53.344864       1 reflector.go:134] github.com/coredns/coredns/plugin/kubernetes/controller.go:322: Failed to list *v1.Namespace: Get https://172.20.0.1:443/api/v1/namespaces?limit=500&resourceVersion=0: dial tcp 172.20.0.1:443: connect: connection refused
E0827 00:44:53.344864       1 reflector.go:134] github.com/coredns/coredns/plugin/kubernetes/controller.go:322: Failed to list *v1.Namespace: Get https://172.20.0.1:443/api/v1/namespaces?limit=500&resourceVersion=0: dial tcp 172.20.0.1:443: connect: connection refused
log: exiting because of error: log: cannot create log: open /tmp/coredns.coredns-57f8cc697b-dnpkj.unknownuser.log.ERROR.20190827-004453.1: no such file or directory

After this patch, CoreDNS stopped crashing.

References

kubernetes/kubernetes#75414
coredns/coredns#2629
https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG-1.14.md#known-issues
coredns/deployment#138

[k8s-ci-robot]

Hi @phspagiari. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[mikesplain]

/ok-to-test

[mikesplain]

To make sure this gets picked up, can you bump the final number here too:

kops/upup/pkg/fi/cloudup/bootstrapchannelbuilder.go

Line 286 in c4ea043

version := "1.3.0-kops.2"

[gjtempleton]

Is it worth adding a note that this can be removed as soon as CoreDNS is upgraded to >=v1.4.0 as per coredns/coredns#2529 ?

[phspagiari]

@mikesplain done!

[phspagiari]

@gjtempleton makes sense, I just added two notes.

[mikesplain]

Just FYI, in the future you can leave -kops.0 on the end which just gives us an easy bump for kops specific changes to manifests

[phspagiari]

Oh, nice to know. I will add -kops.0 in the next one. 👍

[mikesplain]

Thanks @phspagiari!

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mikesplain, phspagiari

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[gjtempleton]

LGTM, and a good catch!