I have two node Kubernetes setup in Virtualbox. Master is up and running fine. But the worker node is staying in "NotReady" state.
[root@master ~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
master Ready master 1d v1.10.2
node NotReady <none> 1h v1.10.2"journalctl -u kubelet" command on worker node is reporting networking related errors:
kuberuntime_manager.go:757] checking backoff for container "install-cni" in pod "kube-flannel-ds-zjlvn_kube-system(873fa36d-4b83-11e8-9997-080027afb5ab)"
remote_runtime.go:278] ContainerStatus "459643e54de7f82df8ada0f60e8f3d51d42c5ce348747a66e20ad5720155e63f" from runtime service failed: rpc error: code = U
kuberuntime_container.go:636] failed to remove pod init container "install-cni": failed to get container status "459643e54de7f82df8ada0f60e8f3d51d42c5ce34
kuberuntime_manager.go:757] checking backoff for container "install-cni" in pod "kube-flannel-ds-zjlvn_kube-system(873fa36d-4b83-11e8-9997-080027afb5ab)"
kuberuntime_manager.go:767] Back-off 10s restarting failed container=install-cni pod=kube-flannel-ds-zjlvn_kube-system(873fa36d-4b83-11e8-9997-080027afb5a
pod_workers.go:186] Error syncing pod 873fa36d-4b83-11e8-9997-080027afb5ab ("kube-flannel-ds-zjlvn_kube-system(873fa36d-4b83-11e8-9997-080027afb5ab)"), sk
cni.go:171] Unable to update cni config: No networks found in /etc/cni/net.d
kubelet.go:2125] Container runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni con
cni.go:171] Unable to update cni config: No networks found in /etc/cni/net.d
kubelet.go:2125] Container runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni con
cni.go:171] Unable to update cni config: No networks found in /etc/cni/net.d
kubelet.go:2125] Container runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni conI am running Kubernetes version 1.10 and docker version 1.13.1. Could you please help me identify the root cause and resolution for this issue?
Well the thing is, when you want to form a kubernetes cluster, it requires that you deploy a CNI plugin which would provide networking between your pods. The error that you have shown here is due to a CNI plugin not being installed or not being configured properly.
The kube-dns pod would be in pending state until the CNI plugin is deployed on your cluster. Once kube-dns moves to a running state, (after deploying the cni provider) you can run your application workloads.
If you have not deployed a CNI plugin, there are several ones you can choose from.
Calico: Provides Pod networking via standard BGP. (Follow the documentation for further info) kubectl apply -f https://docs.projectcalico.org/v3.1/getting-started/kubernetes/installation/hosted/kubeadm/1.7/calico.yaml
Weave: Creates an overlay network. export kubever=$(kubectl version | base64 | tr -d '\n') kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$kubever"
Flannel: Creates an overlay network treating each host as a subnet. kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/v0.9.1/Documentation/kube-flannel.yml
Container traffic needs to be made aware to the iptables and you can do that by sysctl net.bridge.bridge-nf-call-iptables=1 This is required by Flannel and Weave to function.
Please do refer to the documentation of each CNI plugin which would be suitable for your cluster.