Fix: dns-controller: 3999 port address already in use

[vgunapati]

Fixes #4877

The main problem is using the default rolling upgrade strategy. If the dns-controller is created on the same node during the upgrade we are seeing this issue as this is hostNetwork pod

panic: listen tcp4 0.0.0.0:3998: bind: address already in use

example:

dns-controller-5f88fdd576-d8d6m     0/1     CrashLoopBackOff   11         35m   172.16.45.40        ip-172-16-45-40.us-west-2.compute.internal    <none>           <none>
dns-controller-68f76b5848-kdfhm     1/1     Running            0          51m   172.16.45.40        ip-172-16-45-40.us-west-2.compute.internal    <none>           <none>

This PR will use Recreate strategy to avoid this issue

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[k8s-ci-robot]

Hi @vgunapati. 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.

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[vgunapati]

/assign @rdrgmnzs

[hakman]

/cc @johngmyers @olemarkus

[hakman]

/ok-to-test

[olemarkus]

This probably makes sense. It will mean that dns-controller doesn't run between termination and recreation, but I think that is fine.

/lgtm

[johngmyers]

Yeah, normally I'd think pod anti-affinity, but dns-controller doesn't have strong availability requirements.
/lgtm

[vgunapati]

Yeah, normally I'd think pod anti-affinity, but dns-controller doesn't have strong availability requirements.
/lgtm

As we only have one dns-controller pod and did not see any leader election in dns-controller logs nor impact to cluster during Recreate of dns-controller pod I have used Recreate strategy
We can do something like following, for example

spec:
  affinity:
    podAntiAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
      - labelSelector:
          matchExpressions:
          - key: k8s-app
            operator: In
            values:
            - dns-controller
        topologyKey: kubernetes.io/hostname

Please let me know if you want me to change to use podAntiAffinity

[johngmyers]

No, this is good as-is.

[olemarkus]

This one could be a candidate for backport. I guess dns-controller will go into crashloop on every kops upgrade otherwise.

/kind bug

[rifelpet]

I agree this should probably be backported

/approve

[rifelpet]

Travis CI issues... @vgunapati are you able to retry these jobs? https://travis-ci.org/github/kubernetes/kops/builds/700018759 if not can you ammend your commit message and force push back to your branch? we just need to trigger another travis build somehow.

[vgunapati]

@rifelpet I have amended my commit without changes to code. Looks like new travis build just triggered
https://travis-ci.org/github/kubernetes/kops/builds/701094721

[rifelpet]

hopefully that does the trick, thanks!
/lgtm
/approve

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rifelpet, vgunapati

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