Can't Uninstall Flannel

[RMadsenG]

Expected Behavior

kubectl delete -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml
Should cleanly uninstall flannel

Current Behavior

After rebooting a Node pods are stuck in container creating with this error

Warning  FailedCreatePodSandBox  1s    kubelet  (combined from similar events): Failed to create pod sandbox: rpc error: code = Unknown desc = failed to create pod network sandbox k8s_coredns-7c65d6cfc9-prlbd_kube-system_335070f1-cc11-4569-bf97-e2ba7d480ee2_0(a1e1f9e2930f82a9d88d50b6245a88310d610bd04229384a24b354d172c2030e): error adding pod kube-system_coredns-7c65d6cfc9-prlbd to CNI network "cbr0": plugin type="flannel" failed (add): loadFlannelSubnetEnv failed: open /run/flannel/subnet.env: no such file or directory

Possible Solution

Is there Documentation on how to properly remove flannel from a cluster?

Steps to Reproduce (for bugs)

1. kubectl apply -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml
2. Create A Deployment. Pod comes up fine
3. kubectl delete -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml
4. Reboot Node
5. kubectl describe pod
   1. ContainerCreating with error above

Context

I am trying to uninstall flannel and install a CNI that supports NetworkPolicies (kube-router)
Do to the wording of the error, it looks like flannel was not completely uninstalled with the kubectl command.
plugin type="flannel" failed (add): loadFlannelSubnetEnv failed: open /run/flannel/subnet.env: no such file or directory

Your Environment

kubeadm version: &version.Info{Major:"1", Minor:"31", GitVersion:"v1.31.1", GitCommit:"948afe5ca072329a73c8e79ed5938717a5cb3d21", GitTreeState:"clean", BuildDate:"2024-09-11T21:26:49Z", GoVersion:"go1.22.6", Compiler:"gc", Platform:"linux/amd64"}

Launched with kubeadm init --pod-network-cidr=10.244.0.0/16

[rbrtbnfgl]

you should delete also the CNI config /etc/cni/net.d/10-flannel.conflist