stop removing cni directories as they aren't installed by kubeadm

[yastij]

Signed-off-by: Yassine TIJANI ytijani@vmware.com

What type of PR is this?

/kind bug
/priority backlog

What this PR does / why we need it: This PR stops removing /etc/cni/net.d as its removal might break tools that install configuration under this directory. Also, this isn't created by kubeadm. Added a message when using reset like we do for iptables/ipvs

Which issue(s) this PR fixes: Fixes kubernetes/kubeadm#1822

Special notes for your reviewer:

/assign @neolit123

Does this PR introduce a user-facing change?:

kubeadm no longer removes /etc/cni/net.d as it does not install it. Users should remove files from it manually or rely on the component that created them

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[ereslibre]

Thank you @yastij!

/approve
/lgtm

[neolit123]

thanks @yastij

kubeadm no longer removes /etc/cni/net.d as it does not install it. Users should remove it manually or rely on the component that created it

i would re-word to:

Users should remove files from it manually or rely on the component that created them

i'm 50/50 whether this needs action required:, not that it's a breaking change but for better visiblity.
it will definitely cause issues for users that are just trying different CNIs, if multiple networks are in there from my tests CoreDNS just fails.

would you mind sending a PR for this page as well:
https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#pod-network

we need to have a Caution note that users should clean the files of a certain CNI plugin manually before installing a different CNI.

[neolit123]

/cc @ereslibre

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ereslibre, yastij

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[ereslibre]

/hold

Missed @neolit123 review, feel free to unhold when feedback is addressed.

[yastij]

@neolit123 @ereslibre - updated
/hold cancel

[yastij]

/retest

[neolit123]

@yastij
as suggested here we probably should apply this minor clarification to the release note:
#83950 (comment)

[neolit123]

/retest

[neolit123]

/lgtm

[yastij]

/hold cancel

[fejta-bot]

/retest
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[yastij]

/retest