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Upgrading to CoreDNS does not remove kube-dns deployments #6318
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From what I can gather, you can remove the deployments. The With that said, I am unsure if it's within the scope of this project to delete that deployment after switching to CoreDNS. My guess is not, but curious what other people think. |
I can confirm that DNS still seems to be working as expected after scaling down I am also unsure if it's within the scope of this project to delete the deployments, so I'll leave this open for now and see what others think. |
I see two options to make this easier:
I think 1 is better, rather than having lots of printing for various conditions in the code. |
I agree with @joshphp - the upgrade process for coredns is largely undocumented. This is fine for just deploying a cluster, but people running production systems would appreciate more information on how coredns is upgraded. It sounds like this is as simple as adding something to the docs that says:
|
I read everywhere that we should scale |
@jeyglk yes, you can configure the |
The coredns/deployment repo also has a good document on scaling: https://github.com/coredns/deployment/blob/master/kubernetes/Scaling_CoreDNS.md |
@jeyglk After editing our kops cluster to use CoreDNS, I observed that it already created an autoscaler deployment called "coredns-autoscaler", in addition to the pre-existing kube-dns-autoscaler. It seems that there's no need to modify the existing autoscaler rather than just removing it. |
What about the kube-system service/kube-dns ClusterIP 100.64.0.10 <none> 53/UDP,53/TCP,9153/TCP 353d
kube-system configmap/kube-dns-autoscaler 1 353d
kube-system secret/kube-dns-autoscaler-token-8tlgs kubernetes.io/service-account-token 3 353d
kube-system secret/kube-dns-token-rcs8z kubernetes.io/service-account-token 3 353d
kube-system serviceaccount/kube-dns 1 353d
kube-system serviceaccount/kube-dns-autoscaler 1 353d |
See the note at the bottom of this section (Saying the service should be left). I found that to be true when doing this upgrade - removing the service caused DNS to fail. |
@dmcnaught Thank you for pointing it out. I am leaving the service in place then. I also see the doc still says:
I've deleted the kube-dns deployments altogether with: kubectl delete deploy/kube-dns -n kube-system
kubectl delete deploy/kube-dns-autoscaler -n kube-system I did not update kube-dns-autoscaler since there is already $ kubectl get deploy -n kube-system
NAME READY UP-TO-DATE AVAILABLE AGE
calico-kube-controllers 1/1 1 1 464d
coredns 2/2 2 2 152m
coredns-autoscaler 1/1 1 1 152m
... Is this OK? So far, I haven't noticed any issues with the cluster. |
Yeah back when these docs were updated CoreDNS did not have a standalone auto scaler deployed. We should likely update those to reflect the current reality of just deleting the kube-dns deployments. |
1. What
kops
version are you running? The commandkops version
, will displaythis information.
2. What Kubernetes version are you running?
kubectl version
will print theversion if a cluster is running or provide the Kubernetes version specified as
a
kops
flag.3. What cloud provider are you using?
4. What commands did you run? What is the simplest way to reproduce this issue?
Add CoreDNS provider:
Update cluster:
Rolling update:
5. What happened after the commands executed?
Everything ran successfully. However, I still see
kube-dns
deployments:6. What did you expect to happen?
I expected
kube-dns
to be replaced by CoreDNS.7. Please provide your cluster manifest. Execute
kops get --name my.example.com -o yaml
to display your cluster manifest.You may want to remove your cluster name and other sensitive information.
8. Please run the commands with most verbose logging by adding the
-v 10
flag.Paste the logs into this report, or in a gist and provide the gist link here.
9. Anything else do we need to know?
Am I correct in thinking the
kube-dns
deployments should have been deleted?Is it safe to manually delete the deployments?
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