Set Up an HA Cluster Using the Internal HAProxy of KubeKey

KubeKey is an easy-to-use tool for creating Kubernetes clusters. Starting from v1.2.1, KubeKey provides a built-in high availability mode to simplify the creation of highly available Kubernetes clusters. The high availability mode that KubeKey implements is called local load balancing mode. KubeKey deploys a load balancer (HAProxy) on each worker node, and the Kubernetes components on all control planes connect to their local kube-apiserver. The Kubernetes components on each worker node, on the other hand, connect to the kube-apiserver of multiple control planes through a reverse proxy, namely the load balancer deployed by KubeKey. Although this mode is less efficient than a dedicated load balancer because additional health check mechanisms are introduced, it brings a more practical, efficient, and convenient high availability deployment mode when current environment cannot provide an external load balancer or virtual IP (VIP).

This document describes how to use the built-in high availability mode when installing Kube AI Hub on Linux.

Architecture

The following figure shows the example architecture of the built-in high availability mode. For more information about system and network requirements, see Multi-node Installation.

Download KubeKey

Refer to the following steps 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 preceding commands, a configuration file config-sample.yaml is 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.

Enable the built-in high availability mode

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

(Optional) Enable pluggable components

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 is 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, run the following command to start 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
   #####################################################