How to create a local Kubernetes cluster with Multipass and K3s

This tutorial is designed to show how you can create a local Kubernetes cluster with Multipass and K3s.

Prerequisites

A Linux or macOS machine.
kubectl. Refer to the Install and Set Up kubectl page for details about how you can install kubectl.

Create three virtual machines

Install Multipass. Point your browser to the Mulitpass website, and then download the binary for your platform.

Display the list of available images:

 multipass find

 Image                   Aliases           Version          Description
 snapcraft:core          core16            20200318         Snapcraft builder for Core 16
 snapcraft:core18                          20200320         Snapcraft builder for Core 18
 16.04                   xenial            20200318         Ubuntu 16.04 LTS
 18.04                   bionic,lts        20200317         Ubuntu 18.04 LTS

To create a node named master, run the following multipass launch command and pass it the following flags:
- -c with the number of CPUs to allocate (1)
- -m with the amount of memory to allocate (1G). Note that you can use the following suffixes: K, M, and G
- -d with the disk space to allocate (4G). Similarly, note that you can use the following suffixes: K, M, and G
- -n with the name of the node (master)
- The name of the image (18.04)
```
 multipass launch -c 1 -m 1G -d 4G -n k3s-master 18.04
```
```
 Launched: k3s-master
```

Retrieve details about the `master node with:

 multipass info k3s-master

 Name:           k3s-master
 State:          Running
 IPv4:           192.168.64.16
 Release:        Ubuntu 18.04.4 LTS
 Image hash:     fe3030939822 (Ubuntu 18.04 LTS)
 Load:           1.12 1.35 0.61
 Disk usage:     1003.0M out of 3.7G
 Memory usage:   72.4M out of 985.7M

Enter the following Bash script to create two worker nodes named node2 and node3:

 for f in 1 2; do
     multipass launch -c 1 -m 1G -d 4G -n k3s-worker-$f 18.04
 done

 Launched: k3s-worker-1
 Launched: k3s-worker-2

Use the multipass list command to make sure everything went well. The following example output shows that your nodes are in Running state:

 multipass list

 Name                    State             IPv4             Image
 k3s-master              Running           192.168.64.16    Ubuntu 18.04 LTS
 k3s-worker-1            Running           192.168.64.17    Ubuntu 18.04 LTS
 k3s-worker-2            Running           192.168.64.18    Ubuntu 18.04 LTS

Deploy K3s

K3s is a lightweight Kubernetes distribution geared towards resource-constrained environments. Its easy installation process h makes it perfect for rapid prototyping

Use the multipass exec command to deploy K3s to the k3s-master node:

 multipass exec k3s-master -- bash -c "curl -sfL https://get.k3s.io | sh -"

 [INFO]  Finding latest release
 [INFO]  Using v1.17.4+k3s1 as release
 [INFO]  Downloading hash https://github.com/rancher/k3s/releases/download/v1.17.4+k3s1/sha256sum-amd64.txt
 [INFO]  Downloading binary https://github.com/rancher/k3s/releases/download/v1.17.4+k3s1/k3s
 [INFO]  Verifying binary download
 [INFO]  Installing k3s to /usr/local/bin/k3s
 [INFO]  Creating /usr/local/bin/kubectl symlink to k3s
 [INFO]  Creating /usr/local/bin/crictl symlink to k3s
 [INFO]  Creating /usr/local/bin/ctr symlink to k3s
 [INFO]  Creating killall script /usr/local/bin/k3s-killall.sh
 [INFO]  Creating uninstall script /usr/local/bin/k3s-uninstall.sh
 [INFO]  env: Creating environment file /etc/systemd/system/k3s.service.env
 [INFO]  systemd: Creating service file /etc/systemd/system/k3s.service
 [INFO]  systemd: Enabling k3s unit
 Created symlink /etc/systemd/system/multi-user.target.wants/k3s.service → /etc/systemd/system/k3s.service.
 [INFO]  systemd: Starting k3s

Note that, in the above command, everything after -- is passed as an argument to the virtual machine.

The K3s installer created a Kubernetes token on the k3s-master node and saved it into the /var/lib/rancher/k3s/server/node-token file. Execute the following command to store the content of this file into an environment variable called TOKEN:
```
 TOKEN=$(multipass exec k3s-master sudo cat /var/lib/rancher/k3s/server/node-token)
```

You can inspect your Kubernetes token as follows:

 K10a822199e28e2c11a0eb19fe70f483a1a204cf3ee243cc2d12b75fe54c0de66ac::server:3e440ae3b6f4720c6e9c0438c76adc18

 K10db5d436cafc40df4e69e9eaec0df4a35ad982e600e3acecda5264d73859c2618::server:beed2c91b9c38560fc6f82d3649dc94a

Save the IP of your master node into an environment variable named IP

 IP=$(multipass info k3s-master | grep IPv4 | awk '{print $2}')

The following multipass exec command uses the TOKEN and IP environment variables to add the worker nodes to your cluster:

 for f in 1 2; do
     multipass exec k3s-worker-$f -- bash -c "curl -sfL https://get.k3s.io | K3S_URL=\"https://$IP:6443\" K3S_TOKEN=\"$TOKEN\" sh -"
 done

 [INFO]  Finding latest release
 [INFO]  Using v1.17.4+k3s1 as release
 [INFO]  Downloading hash https://github.com/rancher/k3s/releases/download/v1.17.4+k3s1/sha256sum-amd64.txt
 [INFO]  Downloading binary https://github.com/rancher/k3s/releases/download/v1.17.4+k3s1/k3s
 [INFO]  Verifying binary download
 [INFO]  Installing k3s to /usr/local/bin/k3s
 [INFO]  Creating /usr/local/bin/kubectl symlink to k3s
 [INFO]  Creating /usr/local/bin/crictl symlink to k3s
 [INFO]  Creating /usr/local/bin/ctr symlink to k3s
 [INFO]  Creating killall script /usr/local/bin/k3s-killall.sh
 [INFO]  Creating uninstall script /usr/local/bin/k3s-agent-uninstall.sh
 [INFO]  env: Creating environment file /etc/systemd/system/k3s-agent.service.env
 [INFO]  systemd: Creating service file /etc/systemd/system/k3s-agent.service
 [INFO]  systemd: Enabling k3s-agent unit
 Created symlink /etc/systemd/system/multi-user.target.wants/k3s-agent.service → /etc/systemd/system/k3s-agent.service.
 [INFO]  systemd: Starting k3s-agent
 [INFO]  Finding latest release
 [INFO]  Using v1.17.4+k3s1 as release
 [INFO]  Downloading hash https://github.com/rancher/k3s/releases/download/v1.17.4+k3s1/sha256sum-amd64.txt
 [INFO]  Downloading binary https://github.com/rancher/k3s/releases/download/v1.17.4+k3s1/k3s
 [INFO]  Verifying binary download
 [INFO]  Installing k3s to /usr/local/bin/k3s
 [INFO]  Creating /usr/local/bin/kubectl symlink to k3s
 [INFO]  Creating /usr/local/bin/crictl symlink to k3s
 [INFO]  Creating /usr/local/bin/ctr symlink to k3s
 [INFO]  Creating killall script /usr/local/bin/k3s-killall.sh
 [INFO]  Creating uninstall script /usr/local/bin/k3s-agent-uninstall.sh
 [INFO]  env: Creating environment file /etc/systemd/system/k3s-agent.service.env
 [INFO]  systemd: Creating service file /etc/systemd/system/k3s-agent.service
 [INFO]  systemd: Enabling k3s-agent unit
 Created symlink /etc/systemd/system/multi-user.target.wants/k3s-agent.service → /etc/systemd/system/k3s-agent.service.
 [INFO]  systemd: Starting k3s-agent

Verify your cluster

Use the following multipass exec command to open a shell session into the k3s-master and then list the nodes in your cluster:
```
 multipass exec k3s-master -- bash
```
```
 ubuntu@k3s-master:~$
```

Now you can list the nodes in your cluster as follows:

 sudo kubectl get nodes

 NAME           STATUS   ROLES    AGE     VERSION
 k3s-master     Ready    master   11m     v1.17.4+k3s1
 k3s-worker-1   Ready    <none>   4m47s   v1.17.4+k3s1
 k3s-worker-2   Ready    <none>   4m27s   v1.17.4+k3s1

Clean up your cluster

Open a new terminal window (on the host), and then use the multipass stop command to stop your nodes:
```
 multipass stop k3s-master k3s-worker-1 k3s-worker-2
```

Delete your instances with:

 multipass delete k3s-master k3s-worker-1 k3s-worker-2

Permanently delete your instances by entering:
```
 multipass purge
```
Use the multipass list command to verify that the instances were deleted:
```
 multipass list
```
```
 No instances found.
```

Congratulations on completing this tutorial, where you learned how to deploy Kubernetes cluster with Multipath and K3s.

Thanks for reading!