Kubernetesで名前解決できなくなって困った事がったのでメモ

cni0がすでにあるというエラーでした。

# kubectl get pod --all-namespaces 
NAMESPACE     NAME                                       READY   STATUS              RESTARTS   AGE
kube-system   coredns-6d4b75cb6d-9hjwp                   0/1     ContainerCreating   0          25s
kube-system   coredns-6d4b75cb6d-lz4dl                   0/1     ContainerCreating   0          25s
kube-system   etcd-linstor-master02                      1/1     Running             1          39s
kube-system   kube-apiserver-linstor-master02            1/1     Running             1          38s
kube-system   kube-controller-manager-linstor-master02   1/1     Running             1          38s
kube-system   kube-proxy-4ffvr                           1/1     Running             0          11s
kube-system   kube-proxy-r62b5                           1/1     Running             0          10s
kube-system   kube-proxy-rj92f                           0/1     Pending             0          6s
kube-system   kube-proxy-rsthb                           1/1     Running             0          25s
kube-system   kube-scheduler-linstor-master02            1/1     Running             1          39s

# kubectl describe pod coredns-6d4b75cb6d-lz4dl -n kube-system
Events:
  Type     Reason                  Age   From               Message
  ----     ------                  ----  ----               -------
  Normal   Scheduled               59s   default-scheduler  Successfully assigned kube-system/coredns-6d4b75cb6d-lz4dl to linstor-master02
  Warning  FailedCreatePodSandBox  58s   kubelet            Failed to create pod sandbox: rpc error: code = Unknown desc = failed to setup network for sandbox "5b729fceffd1ec702b1040dd856f6d6375c5eaa3bad4d0012a1a88dda710314d": plugin type="flannel" failed (add): failed to delegate add: failed to set bridge addr: "cni0" already has an IP address different from 10.224.0.1/24
  Warning  FailedCreatePodSandBox  45s   kubelet            Failed to create pod sandbox: rpc error: code = Unknown desc = failed to setup network for sandbox "10304b386803230d68d2cf54df60df31efac23070567d1962088a68ce89fdcab": plugin type="flannel" failed (add): failed to delegate add: failed to set bridge addr: "cni0" already has an IP address different from 10.224.0.1/24
  Warning  FailedCreatePodSandBox  35s   kubelet            Failed to create pod sandbox: rpc error: code = Unknown desc = failed to setup network for sandbox "7907fdfa62306f9e79d4b11f70bf59b4db2fc8fc4455c1d1c079c187e1a8ace2": plugin type="flannel" failed (add): failed to delegate add: failed to set bridge addr: "cni0" already has an IP address different from 10.224.0.1/24
  Warning  FailedCreatePodSandBox  23s   kubelet            Failed to create pod sandbox: rpc error: code = Unknown desc = failed to setup network for sandbox "f75551eb1886794291b837561974d8758e57e00669748d9f8960e1285fca76e8": plugin type="flannel" failed (add): failed to delegate add: failed to set bridge addr: "cni0" already has an IP address different from 10.224.0.1/24
  Warning  FailedCreatePodSandBox  8s    kubelet            Failed to create pod sandbox: rpc error: code = Unknown desc = failed to setup network for sandbox "cf343dbc894e0913f8901776a48d81c0ddf91ea3dfa2832582c08f0789c27f48": plugin type="flannel" failed (add): failed to delegate add: failed to set bridge addr: "cni0" already has an IP address different from 10.224.0.1/24

全ノードで、resetしてから、cni0とflannel.1を削除した後、initし直したらcorednsも上がり治りました。

kubeadm reset
ip link delete cni0 && ip link delete flannel.1
kubeadm init