Adding documentation to mitigate workload outages on AWS

[endzyme]

When running the upgrade process to quickly roll all the master, you can enter a state which causes nodes to become NotReady. This can lead to nodes (potentially all nodes) being removed from ELBs managed by Kubernetes Services type LoadBalancer. In order to avoid this you can add an IAM policy which temporarily blocks Kubernetes from removing nodes from ELBs, thus mitigating the temporary reconciliation state.

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[rifelpet]

/ok-to-test

[chrisz100]

/lgtm
/approve

[KashifSaadat]

Thanks for the contribution @endzyme !

/retest
/lgtm
/approve

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: chrisz100, endzyme, KashifSaadat

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[drewwells]

When running the upgrade process to quickly roll all the master, you can enter a state which causes nodes to become NotReady. This can lead to nodes (potentially all nodes) being removed from ELBs managed by Kubernetes Services type LoadBalancer. In order to avoid this you can add an IAM policy which temporarily blocks Kubernetes from removing nodes from ELBs, thus mitigating the temporary reconciliation state.

@endzyme did this actually happen to you? This corner case sounds more reasonable if a network partition was encountered. while etcd is down, kube-apiserver is down, kcm can not get notready status. once kube-apiserver is back up, kubelets will be checking in to update ready status

[endzyme]

Yes it was quite common on our upgrade pattern at my last company. I can't recall specifics after this amount of time but I might be able to put you in touch with others still at the company.