I am trying to configure a 2 node Kubernetes cluster. First I am trying to configure the master node of the cluster on a CentOS VM. I have initialized the cluster using 'kubeadm init --apiserver-advertise-address=172.16.100.6 --pod-network-cidr=10.244.0.0/16' and deployed the flannel network to the cluster. But when I do 'kubectl get nodes', I get the following output ----
[root@kubernetus ~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
kubernetus NotReady master 57m v1.12.0
Following is the output of 'kubectl get pods --all-namespaces -o wide ' ----
[root@kubernetus ~]# kubectl get pods --all-namespaces -o wide
NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE
kube-system coredns-576cbf47c7-9x59x 0/1 Pending 0 58m <none> <none> <none>
kube-system coredns-576cbf47c7-l52wc 0/1 Pending 0 58m <none> <none> <none>
kube-system etcd-kubernetus 1/1 Running 2 57m 172.16.100.6 kubernetus <none>
kube-system kube-apiserver-kubernetus 1/1 Running 2 57m 172.16.100.6 kubernetus <none>
kube-system kube-controller-manager-kubernetus 1/1 Running 1 57m 172.16.100.6 kubernetus <none>
kube-system kube-proxy-hr557 1/1 Running 1 58m 172.16.100.6 kubernetus <none>
kube-system kube-scheduler-kubernetus 1/1 Running 1 57m 172.16.100.6 kubernetus <none>
coredns is in a pending state for a very long time. I have removed docker and kubectl, kubeadm, kubelet a no of times & tried to recreate the cluster, but every time it shows the same output. Can anybody help me with this issue?
About CoreDNS Like Kubernetes, the CoreDNS project is hosted by the CNCF. You can use CoreDNS instead of kube-dns in your cluster by replacing kube-dns in an existing deployment, or by using tools like kubeadm that will deploy and upgrade the cluster for you.
If a Pod is stuck in Pending it means that it can not be scheduled onto a node. Generally this is because there are insufficient resources of one type or another that prevent scheduling.
In Kubernetes version 1.11 and later, CoreDNS is recommended and is installed by default with kubeadm. For more information on how to configure CoreDNS for a Kubernetes cluster, see the Customizing DNS Service.
Try to install Pod network add-on (Base on this guide).
Run this line:
kubectl apply -f https://docs.projectcalico.org/v3.14/manifests/calico.yaml
Unable to update cni config: No networks found in /etc/cni/net.d ..... Oct 02 19:21:32 kubernetus kubelet[19007]: E1002 19:21:32.886170 19007 kubelet.go:2167] Container runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni config uninitialized
According to this error, you forgot to initialize a Kubernetes Pod network add-on. Looking at your settings, I suppose it should be Flannel.
Here is the instruction from the official Kubernetes documentation:
For flannel to work correctly, you must pass
--pod-network-cidr=10.244.0.0/16
to kubeadm init.Set
/proc/sys/net/bridge/bridge-nf-call-iptables
to 1 by runningsysctl net.bridge.bridge-nf-call-iptables=1
to pass bridged IPv4 traffic to iptables’ chains. This is a requirement for some CNI plugins to work, for more information please see here.kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/v0.10.0/Documentation/kube-flannel.yml
Note that flannel works on amd64, arm, arm64 and ppc64le, but until flannel v0.11.0 is released you need to use the following manifest that supports all the architectures:
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/c5d10c8/Documentation/kube-flannel.yml
For more information, you can visit this link.
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