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Install a Multi-node Kubernetes and KubeSphere Cluster

In a production environment, a single-node cluster cannot satisfy most of the needs as the cluster has limited resources with insufficient compute capabilities. Thus, single-node clusters are not recommended for large-scale data processing. Besides, a cluster of this kind is not available with high availability as it only has one node. On the other hand, a multi-node architecture is the most common and preferred choice in terms of application deployment and distribution.

This section gives you an overview of a single-master multi-node installation, including the concept, KubeKey and steps. For information about HA installation, refer to High Availability Configurations, Installing on Public Cloud and Installing in On-premises Environment.

Video Demonstration

Concept

A multi-node cluster is composed of at least one master node and one worker node. You can use any node as the taskbox to carry out the installation task. You can add additional nodes based on your needs (for example, for high availability) both before and after the installation.

Master. A master node generally hosts the control plane that controls and manages the whole system.
Worker. Worker nodes run the actual applications deployed on them.

Step 1: Prepare Linux Hosts

Please see the requirements for hardware and operating system shown below. To get started with multi-node installation in this tutorial, you need to prepare at least three hosts according to the following requirements. It is possible to install the KubeSphere Container Platform on two nodes if they have sufficient resources.

System requirements

Systems	Minimum Requirements (Each node)
Ubuntu 16.04, 18.04	CPU: 2 Cores, Memory: 4 G, Disk Space: 40 G
Debian Buster, Stretch	CPU: 2 Cores, Memory: 4 G, Disk Space: 40 G
CentOS 7.x	CPU: 2 Cores, Memory: 4 G, Disk Space: 40 G
Red Hat Enterprise Linux 7	CPU: 2 Cores, Memory: 4 G, Disk Space: 40 G
SUSE Linux Enterprise Server 15 /openSUSE Leap 15.2	CPU: 2 Cores, Memory: 4 G, Disk Space: 40 G

Note

The path /var/lib/docker is mainly used to store the container data, and will gradually increase in size during use and operation. In the case of a production environment, it is recommended that /var/lib/docker should mount a drive separately.

Node requirements

All nodes must be accessible through SSH.
Time synchronization for all nodes.
sudo/curl/openssl should be used in all nodes.

Container runtimes

Your cluster must have an available container runtime. If you use KubeKey to set up a cluster, KubeKey will install the latest version of Docker by default. Alternatively, you can install Docker or other container runtimes by yourself before you create a cluster.

Supported Container Runtime	Version
Docker	19.3.8+
containerd (experimental, not fully tested)	Latest
CRI-O (experimental, not fully tested)	Latest
iSula (experimental, not fully tested)	Latest

Note

A container runtime must be installed in advance if you want to deploy KubeSphere in an offline environment.

Dependency requirements

KubeKey can install Kubernetes and KubeSphere together. The dependency that needs to be installed may be different based on the Kubernetes version to be installed. You can refer to the list below to see if you need to install relevant dependencies on your node in advance.

Dependency	Kubernetes Version ≥ 1.18	Kubernetes Version < 1.18
`socat`	Required	Optional but recommended
`conntrack`	Required	Optional but recommended
`ebtables`	Optional but recommended	Optional but recommended
`ipset`	Optional but recommended	Optional but recommended

Network and DNS requirements

Make sure the DNS address in /etc/resolv.conf is available. Otherwise, it may cause some issues of DNS in clusters.
If your network configuration uses firewall rules or security groups, you must ensure infrastructure components can communicate with each other through specific ports. It’s recommended that you turn off the firewall or follow the guide Port Requirements.
Supported CNI plugins: Calico and Flannel. Others (such as Cilium and Kube-OVN) may also work but note that they have not been fully tested.

Tip

It’s recommended that your OS be clean (without any other software installed). Otherwise, there may be conflicts.
A registry mirror (booster) is recommended to be prepared if you have trouble downloading images from dockerhub.io. See Configure a Booster for Installation and Configure registry mirrors for the Docker daemon.

This example includes three hosts as below with the master node serving as the taskbox.

Host IP	Host Name	Role
192.168.0.2	master	master, etcd
192.168.0.3	node1	worker
192.168.0.4	node2	worker

Step 2: Download KubeKey

Follow the step below to download KubeKey.

Download KubeKey from its GitHub Release Page or use the following command directly.

curl -sfL https://get-kk.kubesphere.io | VERSION=v1.1.1 sh -

Run the following command first to make sure you download KubeKey from the correct zone.

export KKZONE=cn

Run the following command to download KubeKey:

curl -sfL https://get-kk.kubesphere.io | VERSION=v1.1.1 sh -

Note

After you download KubeKey, if you transfer it to a new machine also with poor network connections to Googleapis, you must run export KKZONE=cn again before you proceed with the steps below.

Note

The commands above download the latest release (v1.1.1) of KubeKey. You can change the version number in the command to download a specific version.

Make kk executable:

chmod +x kk

Step 3: Create a Kubernetes Multi-node Cluster

For multi-node installation, you need to create a cluster by specifying a configuration file.

1. Create an example configuration file

Command:

./kk create config [--with-kubernetes version] [--with-kubesphere version] [(-f | --file) path]

Note

Recommended Kubernetes versions for KubeSphere v3.1.1: v1.17.9, v1.18.8, v1.19.8, and v1.20.4. If you do not specify a Kubernetes version, KubeKey will install Kubernetes v1.19.8 by default. For more information about supported Kubernetes versions, see Support Matrix.
If you do not add the flag --with-kubesphere in the command in this step, KubeSphere will not be deployed unless you install it using the addons field in the configuration file or add this flag again when you use ./kk create cluster later.
If you add the flag --with-kubesphere without specifying a KubeSphere version, the latest version of KubeSphere will be installed.

Here are some examples for your reference:

You can create an example configuration file with default configurations. You can also specify the file with a different filename, or in a different folder.
```
./kk create config [-f ~/myfolder/abc.yaml]
```
You can specify a KubeSphere version that you want to install (for example, --with-kubesphere v3.1.1).
```
./kk create config --with-kubesphere [version]
```

2. Edit the configuration file of a Kubernetes multi-node cluster

A default file config-sample.yaml will be created if you do not change the name. Edit the file and here is an example of the configuration file of a multi-node cluster with one master node.

Note

To customize Kubernetes related parameters, refer to Kubernetes Cluster Configurations.

spec:
  hosts:
  - {name: master, address: 192.168.0.2, internalAddress: 192.168.0.2, user: ubuntu, password: Testing123}
  - {name: node1, address: 192.168.0.3, internalAddress: 192.168.0.3, user: ubuntu, password: Testing123}
  - {name: node2, address: 192.168.0.4, internalAddress: 192.168.0.4, user: ubuntu, password: Testing123}
  roleGroups:
    etcd:
    - master
    master:
    - master
    worker:
    - node1
    - node2
  controlPlaneEndpoint:
    domain: lb.kubesphere.local
    address: ""
    port: "6443"

Hosts

List all your machines under hosts and add their detailed information as above.

name: The hostname of the instance.

address: The IP address you use for the connection between the taskbox and other instances through SSH. This can be either the public IP address or the private IP address depending on your environment. For example, some cloud platforms provide every instance with a public IP address which you use to access instances through SSH. In this case, you can provide the public IP address for this field.

internalAddress: The private IP address of the instance.

At the same time, you must provide the login information used to connect to each instance. Here are some examples:

For password login:
```
hosts:
  - {name: master, address: 192.168.0.2, internalAddress: 192.168.0.2, port: 8022, user: ubuntu, password: Testing123}
```
Note

In this tutorial, port 22 is the default port of SSH so you do not need to add it in the YAML file. Otherwise, you need to add the port number after the IP address as above.

For the default root user:

hosts:
  - {name: master, address: 192.168.0.2, internalAddress: 192.168.0.2, password: Testing123}

For passwordless login with SSH keys:

hosts:
  - {name: master, address: 192.168.0.2, internalAddress: 192.168.0.2, privateKeyPath: "~/.ssh/id_rsa"}

For installation on ARM devices:

hosts:
  - {name: master, address: 192.168.0.2, internalAddress: 192.168.0.2, user: ubuntu, password: Testing123, arch: arm64}

Tip

Before you install KubeSphere, you can use the information provided under hosts (for example, IP addresses and passwords) to test the network connection between the taskbox and other instances using SSH.
Make sure port 6443 is not being used by other services before the installation. Otherwise, it may cause conflicts as the default port of the API server is 6443.

roleGroups

etcd: etcd node names
master: Master node names
worker: Worker node names

controlPlaneEndpoint (for HA installation only)

The controlPlaneEndpoint is where you provide your external load balancer information for an HA cluster. You need to prepare and configure the external load balancer if and only if you need to install multiple master nodes. Please note that the address and port should be indented by two spaces in config-sample.yaml, and address should be your load balancer’s IP address. See HA Configurations for details.

addons

You can customize persistent storage plugins (for example, NFS Client, Ceph RBD, and GlusterFS) by specifying storage under the field addons in config-sample.yaml. For more information, see Persistent Storage Configurations.

KubeKey will install OpenEBS to provision LocalPV for development and testing environment by default, which is convenient for new users. In this example of multi-node installation, the default storage class (local volume) is used. For production, you can use Ceph/GlusterFS/CSI or commercial products as persistent storage solutions.

Tip

You can enable the multi-cluster feature by editing the configuration file. For more information, see Multi-cluster Management.
You can also select the components you want to install. For more information, see Enable Pluggable Components. For an example of a complete config-sample.yaml file, see this file.

When you finish editing, save the file.

3. Create a cluster using the configuration file

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

Note

You need to change config-sample.yaml above to your own file if you use a different name.

The whole installation process may take 10-20 minutes, depending on your machine and network.

4. Verify the installation

When the installation finishes, you can see the content as follows:

#####################################################
###              Welcome to KubeSphere!           ###
#####################################################

Console: http://192.168.0.2:30880
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             20xx-xx-xx xx:xx:xx
#####################################################

Now, you will be able to access the web console of KubeSphere at <NodeIP>:30880 with the default account and password (admin/P@88w0rd).

Note

To access the console, you may need to configure port forwarding rules depending on your environment. Please also make sure port 30880 is opened in your security group.

Enable kubectl Autocompletion

KubeKey doesn’t enable kubectl autocompletion. See the content below and turn it on:

Note

Make sure bash-autocompletion is installed and works.

# Install bash-completion
apt-get install bash-completion

# Source the completion script in your ~/.bashrc file
echo 'source <(kubectl completion bash)' >>~/.bashrc

# Add the completion script to the /etc/bash_completion.d directory
kubectl completion bash >/etc/bash_completion.d/kubectl

Detailed information can be found here.

Code Demonstration

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