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Kubernetes : Add Control Plane Node2024/06/07


Add new Control Plane Nodes to existing Kubernetes Cluster.

This example is based on the cluster environment like follows.
It adds [dlp-1.srv.world (] as Control Plane Node to this cluster.

When etcd is started on the Control Plane, the fault tolerance of etcd is 0 for 1-2 units, so in a configuration with 2 Control Planes, if one of them goes down, it will no longer be possible to connect to etcd and the cluster will not be able to be used normally.

+----------------------+   +----------------------+
|  [ ctrl.srv.world ]  |   |   [ dlp.srv.world ]  |
|     Manager Node     |   |     Control Plane    |
+-----------+----------+   +-----------+----------+
        eth0|             eth0|
            |                          |
            |                          |
        eth0|             eth0|
+-----------+----------+   +-----------+----------+
| [ node01.srv.world ] |   | [ node02.srv.world ] |
|     Worker Node#1    |   |     Worker Node#2    |
+----------------------+   +----------------------+


On a new Node, Configure common settings to join in Cluster, refer to here.

[2] Add proxy setting for new Control Plane on Manager Node.
vi /etc/nginx/nginx.conf
# add new Control Plane
stream {
    upstream k8s-api {
    server {
        listen 6443;
        proxy_pass k8s-api;

systemctl reload nginx
[3] Confirm join command on existing Control Plane Node and also transfer certificate files to new Node with any user.
cd /etc/kubernetes/pki

tar czvf kube-certs.tar.gz sa.pub sa.key ca.crt ca.key front-proxy-ca.crt front-proxy-ca.key etcd/ca.crt etcd/ca.key

scp kube-certs.tar.gz ubuntu@
kubeadm token create --print-join-command

kubeadm join --token h8bpe5.ank6u1ui211x4e5z --discovery-token-ca-cert-hash sha256:9cb21e3807780e1acf9ad9b6369ce54b1141ecf007d099675b23b6c3368494c9
[4] Run join command you confirmed on a new Node with [--control-plane] option.
# copy certificates transferred from existing Control Plane

mkdir /etc/kubernetes/pki

tar zxvf /tmp/kube-certs.tar.gz -C /etc/kubernetes/pki
kubeadm join --token h8bpe5.ank6u1ui211x4e5z \
--discovery-token-ca-cert-hash sha256:9cb21e3807780e1acf9ad9b6369ce54b1141ecf007d099675b23b6c3368494c9 \

[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[preflight] Running pre-flight checks before initializing the new control plane instance
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'


This node has joined the cluster and a new control plane instance was created:

* Certificate signing request was sent to apiserver and approval was received.
* The Kubelet was informed of the new secure connection details.
* Control plane label and taint were applied to the new node.
* The Kubernetes control plane instances scaled up.
* A new etcd member was added to the local/stacked etcd cluster.

To start administering your cluster from this node, you need to run the following as a regular user:

        mkdir -p $HOME/.kube
        sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
        sudo chown $(id -u):$(id -g) $HOME/.kube/config

Run 'kubectl get nodes' to see this node join the cluster.
[5] Verify settings on Manager Node. That's OK if the status of new Node turns to [STATUS = Ready].
kubectl get nodes

NAME               STATUS   ROLES           AGE    VERSION
dlp-1.srv.world    Ready    control-plane   67s    v1.30.1
dlp.srv.world      Ready    control-plane   143m   v1.30.1
node01.srv.world   Ready    <none>          138m   v1.30.1
node02.srv.world   Ready    <none>          137m   v1.30.1

kubectl get pods -A -o wide | grep dlp-1

kube-system   calico-node-7sqz9                         1/1     Running   0             112s        dlp-1.srv.world    <none>           <none>
kube-system   etcd-dlp-1.srv.world                      1/1     Running   0             110s        dlp-1.srv.world    <none>           <none>
kube-system   kube-apiserver-dlp-1.srv.world            1/1     Running   0             110s        dlp-1.srv.world    <none>           <none>
kube-system   kube-controller-manager-dlp-1.srv.world   1/1     Running   0             110s        dlp-1.srv.world    <none>           <none>
kube-system   kube-proxy-6bf8b                          1/1     Running   0             112s        dlp-1.srv.world    <none>           <none>
kube-system   kube-scheduler-dlp-1.srv.world            1/1     Running   0             110s        dlp-1.srv.world    <none>           <none>
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