> ## Documentation Index
> Fetch the complete documentation index at: https://docs.apinizer.com/llms.txt
> Use this file to discover all available pages before exploring further.

# IP Change in Kubernetes Cluster - Virtual IP Usage

> You can change IP in Kubernetes cluster, use virtual IP to provide uninterrupted service, and configure it to work with high availability.

In this document, we will ensure that our existing Kubernetes cluster works with high availability without interruption by redirecting it to a virtual IP without breaking it.

**Existing Machines:**

* Kubernetes Master1
* Kubernetes Master2
* Kubernetes Master3
* Kubernetes Worker1
* Kubernetes Worker2

## 1) Existing System and Virtual IP Access

In the existing system, a Kubernetes cluster was created on **Master1** with the **kubeadm init** command, and then other machines (Master2, Master3, Worker1 and Worker2) were included in this cluster with the **worker** role.

By defining a **Virtual IP** on the Load Balancer, we need to make existing machines accessible from this **Virtual IP** on port **6443**.

<Warning>
  If you are not using a load balancer and cannot create a virtual IP on the network, you can check the [Kubernetes High Availability Cluster Installation](/en/setup/kubernetes/kubernetes-high-availability-cluster) page to perform this operation with **Keepalived** and **HAProxy** tools that you can use for this.

  **Keepalived** is used to create virtual IP, and **HAProxy** is used for load balancing operations.
</Warning>

## 2) IP Change

When there are multiple master nodes in the cluster, we need to reconfigure the cluster to leave these masters as a single master.

This operation usually starts by completely removing other masters from the cluster.

The following command is run for other masters (**master2 and master3**) **except master1**.

```bash theme={null}
sudo kubeadm reset
```

Other masters (master2 and master3) are deleted from the cluster from Master1 server.

```bash theme={null}
kubectl delete nodes master2
kubectl delete nodes master3
```

Master1 and worker servers should remain in the existing system.

### 2.1) What to do on Master1 server:

Kubelet and containerd **(if docker is used, also the docker application)** are stopped.

```bash theme={null}
sudo systemctl stop kubelet
sudo systemctl stop containerd
```

Backups of some files are taken and deleted.

```bash theme={null}
sudo mv -f /etc/kubernetes /etc/kubernetes.backup
sudo mv -f /var/lib/kubelet /var/lib/kubelet.backup
sudo mkdir -p /etc/kubernetes/pki
sudo cp -r /etc/kubernetes_backup/pki /etc/kubernetes
sudo rm -rf /etc/kubernetes/pki/{apiserver.*,etcd/peer.*}
sudo rm -f ~/.kube/config
```

Containerd **(if docker is used, also the docker application)** is started.

```bash theme={null}
sudo systemctl start containerd
```

The Kubeadm init command is run again by editing the endpoint address and **Virtual IP** is used.

```bash theme={null}
sudo kubeadm init --pod-network-cidr "10.244.0.0/16" --control-plane-endpoint <VIRTUAL_IP> --upload-certs --ignore-preflight-errors=DirAvailable--var-lib-etcd
```

**Note:** Kubeadm **join** commands are noted.

### 2.2) What to do for Worker1 and Worker2:

Kubelet and containerd (if docker is used, also the docker application) are stopped.

```bash theme={null}
sudo systemctl stop kubelet
sudo systemctl stop containerd
```

Backups of some files are taken.

```bash theme={null}
sudo mv -f /etc/kubernetes /etc/kubernetes.backup
sudo mv -f /var/lib/kubelet /var/lib/kubelet.backup
```

Containerd (if docker is used, also the docker application) and kubelet are started.

```bash theme={null}
sudo systemctl start kubelet
sudo systemctl start containerd
```

Kubeadm **worker join** command is run on **worker1** and **worker2** machines.

### 2.3) What to do for Master2 and Master3:

In this step, it will be sufficient to run only the **master join** command on master2 and master3.

### 2.4) Cluster Status Check:

You can see your new cluster information with the following commands.

```bash theme={null}
kubectl cluster-info
kubectl get node -o wide
```