Set up an HA Cluster Using a Load Balancer

You can set up Kubernetes cluster (a control plane node) with Kube AI Hub installed based on the tutorial of Multi-node Installation. Clusters with a control plane node may be sufficient for development and testing in most cases. For a production environment, however, you need to consider the high availability of the cluster. If key components (for example, kube-apiserver, kube-scheduler, and kube-controller-manager) are all running on the same control plane node, Kubernetes and Kube AI Hub will be unavailable once the control plane node goes down. Therefore, you need to set up a high-availability cluster by provisioning load balancers with multiple control plane nodes. You can use any cloud load balancer, or any hardware load balancer (for example, F5). In addition, Keepalived and HAproxy, or Nginx is also an alternative for creating high-availability clusters.

This tutorial demonstrates the general configurations of a high-availability cluster as you install Kube AI Hub on Linux.

Architecture

Make sure you have prepared six Linux machines before you begin, with three of them serving as control plane nodes and the other three as worker nodes. The following diagram shows the recommended layout. For more information about system and network requirements, see Multi-node Installation.

Configure a Load Balancer

You must create a load balancer in your environment to listen (also known as listeners on some cloud platforms) on key ports. Here is a table of recommended ports that need to be listened on.

Download KubeKey

Kubekey is the next-gen installer which provides an easy, fast and flexible way to install Kubernetes and Kube AI Hub. Follow the steps below to download KubeKey.

curl -sfL https://get-kk.kubesphere.io | VERSION=v3.0.13  sh -

export KKZONE=cn

curl -sfL https://get-kk.kubesphere.io | VERSION=v3.0.13  sh -

Make kk executable:

chmod +x kk

Create an example configuration file with default configurations. Here Kubernetes v1.22.12 is used as an example.

./kk create config --with-kubesphere v3.4.1 --with-kubernetes v1.22.12

Deploy Kube AI Hub and Kubernetes

After you run the commands above, a configuration file config-sample.yaml will be created. Edit the file to add machine information, configure the load balancer and more.

config-sample.yaml example

spec:
  hosts:
  - {name: master1, address: 192.168.0.2, internalAddress: 192.168.0.2, user: ubuntu, password: Testing123}
  - {name: master2, address: 192.168.0.3, internalAddress: 192.168.0.3, user: ubuntu, password: Testing123}
  - {name: master3, address: 192.168.0.4, internalAddress: 192.168.0.4, user: ubuntu, password: Testing123}
  - {name: node1, address: 192.168.0.5, internalAddress: 192.168.0.5, user: ubuntu, password: Testing123}
  - {name: node2, address: 192.168.0.6, internalAddress: 192.168.0.6, user: ubuntu, password: Testing123}
  - {name: node3, address: 192.168.0.7, internalAddress: 192.168.0.7, user: ubuntu, password: Testing123}
  roleGroups:
    etcd:
    - master1
    - master2
    - master3
    control-plane:
    - master1
    - master2
    - master3
    worker:
    - node1
    - node2
    - node3

For more information about different fields in this configuration file, see Kubernetes Cluster Configurations and Multi-node Installation.

Configure the load balancer

spec:
  controlPlaneEndpoint:
    ##Internal loadbalancer for apiservers
    #internalLoadbalancer: haproxy
    
    domain: lb.kubesphere.local
    address: "192.168.0.xx"
    port: 6443

Persistent storage plugin configurations

For a production environment, you need to prepare persistent storage and configure the storage plugin (for example, CSI) in config-sample.yaml to define which storage service you want to use. For more information, see Persistent Storage Configurations.

Enable pluggable components (Optional)

Kube AI Hub has decoupled some core feature components since v2.1.0. These components are designed to be pluggable which means you can enable them either before or after installation. By default, Kube AI Hub will be installed with the minimal package if you do not enable them.

You can enable any of them according to your demands. It is highly recommended that you install these pluggable components to discover the full-stack features and capabilities provided by Kube AI Hub. Make sure your machines have sufficient CPU and memory before enabling them. See Enable Pluggable Components for details.

Start installation

After you complete the configuration, you can execute the following command to start the installation:

./kk create cluster -f config-sample.yaml

Verify installation

1. Run the following command to inspect the logs of installation.

   kubectl logs -n kubesphere-system $(kubectl get pod -n kubesphere-system -l 'app in (ks-install, ks-installer)' -o jsonpath='{.items[0].metadata.name}') -f
   

2. When you see the following message, it means your HA cluster is successfully created.

   #####################################################
   ###              Welcome to Kube AI Hub!           ###
   #####################################################
   
   Console: http://192.168.0.3:30880
   Account: admin
   Password: P@88w0rd
   
   NOTES：
     1. After you log into the console, please check the
        monitoring status of service components in
        the "Cluster Management". If any service is not
        ready, please wait patiently until all components
        are up and running.
     2. Please change the default password after login.
   
   #####################################################
   https://kubesphere.io             2020-xx-xx xx:xx:xx
   #####################################################