Add New Nodes

After you use KubeSphere for a certain period of time, it is likely that you need to scale out your cluster with an increasing number of workloads. From KubeSphere v3.0.0, you can use the brand-new installer KubeKey to add new nodes to a cluster. Fundamentally, the operation is based on Kubelet’s registration mechanism. In other words, the new nodes will automatically join the existing Kubernetes cluster. KubeSphere supports hybrid environments, which means the newly-added host OS can be CentOS or Ubuntu.

This tutorial demonstrates how to add new nodes to a single-node cluster. To scale out a multi-node cluster, the steps are basically the same.

Prerequisites

• You need to have a single-node cluster. For more information, see All-in-One Installation on Linux.

• You have downloaded KubeKey.

Add New Nodes

Step 1: Modify host configurations

1. Create a configuration file (config-sample.yaml) using KubeKey.

   # Assume your original Kubernetes cluster is v1.17.9
   ./kk create config --with-kubesphere v3.0.0 --with-kubernetes v1.17.9
   

   Note

   You can skip this step if you already have the configuration file on your machine. For example, if you want to add nodes to a multi-node cluster which was set up by KubeKey, you might still have the configuration file if you have not deleted it.

2. In the configuration file, put the information of your new nodes under hosts and roleGroups. The example adds two new nodes (i.e. node1 and node2). Here master1 is the existing node.

   spec:
     hosts:
     - {name: master1, address: 192.168.0.3, internalAddress: 192.168.0.3, user: root, password: [email protected]}
     - {name: node1, address: 192.168.0.4, internalAddress: 192.168.0.4, user: root, password: [email protected]}
     - {name: node2, address: 192.168.0.5, internalAddress: 192.168.0.5, user: root, password: [email protected]}
     roleGroups:
       etcd:
       - master1
       master:
       - master1
       worker:
       - node1
       - node2
   ···
   

   Note

   • For more information about the configuration file, see Edit the configuration file.
   • You are not allowed to modify the host name of existing nodes when adding new nodes.
   • Replace the host name in the example with your own.

Step 2: Apply the configuration to add nodes

1. Execute the following command:

   ./kk add nodes -f config-sample.yaml
   

2. You will be able to see the new nodes and their information on the KubeSphere console when the installation finishes. On the Cluster Management page, select Cluster Nodes under Nodes from the left menu, or execute the command kubectl get node to check the changes.

   $ kubectl get node
   NAME          STATUS   ROLES           AGE   VERSION
   master1       Ready    master,worker   20d   v1.17.9
   node1         Ready    worker          31h   v1.17.9
   node2         Ready    worker          31h   v1.17.9