Removing of "kube-dns" svc in cleanup_dns.yml is a Bug

[wobu]

We stumpled upon a k8s cluster upgrade issue using kubespray 2.15.1. But i am sure this problem is a general conceptual issue affecting all kubespray releases.

We tried to upgrade from k8s version 1.18.15 to 1.19.9

As my understanding, kubeadm and kubernetes expects for a smoother transition from kube-dns to coredns that the coredns installation still uses the kube-dns service, See: https://kubernetes.io/docs/tasks/administer-cluster/dns-custom-nameservers/#introduction

Note: The CoreDNS Service is named kube-dns in the metadata.name field.
This is so that there is greater interoperability with workloads that relied on the legacy kube-dns Service name to resolve addresses internal to the cluster. Using a Service named kube-dns abstracts away the implementation detail of which DNS provider is running behind that common name.

Linked issues:

• unable to create/update the DNS service: Service \"kube-dns\" is invalid: #7745
• FATAL post-upgrade error: unable to create/update the DNS service: services "kube-dns" not found #7083

The mentioned workarounds in the linked issues therefore needs to be done after each cluster-upgrade, therefore i suggest remove the deletion of the kube-dns svc in cleanup_dns.yml would be the best solution.

Environment:

• HP, Proxmox, BareMetal

• Ubuntu 20.04 LTS

Kubespray version:: v2.15.1 (we used following dokcer image quay.io/kubespray/kubespray:v2.15.1)

Network plugin used: Calico

Command used to invoke ansible: ansible-playbook -i inventory/sample/hosts.yaml upgrade-cluster.yml

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all issues and PRs.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue or PR as fresh with /remove-lifecycle stale
• Mark this issue or PR as rotten with /lifecycle rotten
• Close this issue or PR with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue or PR as fresh with /remove-lifecycle rotten
• Close this issue or PR with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle rotten

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Reopen this issue with /reopen
• Mark this issue as fresh with /remove-lifecycle rotten
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/close not-planned

[k8s-ci-robot]

@k8s-triage-robot: Closing this issue, marking it as "Not Planned".

In response to this:

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Reopen this issue with /reopen
• Mark this issue as fresh with /remove-lifecycle rotten
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/close not-planned

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.