Tag: K3s

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Upgrade of a K3s Lightweight Kubernetes Cluster

K3s is a lightweight, highly available open source Kubernetes cluster platform designed for easy and resource-efficient installation. K3s is provided in a package of less than 60 MB. The package is optimized for ARM platforms and can therefore also be run on hardware such as a Raspberry Pi, or as a guest VM on ESXi-on-ARM.

Prerequisites and collection of information

K3s is a cluster solution. That is why the order in which the nodes are updated is important. The update starts on the master node. So first we need to find out which node has this role. The easiest way to do this is with a kubectl command:

kubectl get node
NAME STATUS ROLES AGE VERSION
k3node1.lab.local Ready master 2y43d v1.19.3+k3s3
k3node2.lab.local Ready none 2y42d v1.19.3+k3s3
k3node3.lab.local Ready none 2y42d v1.19.3+k3s3

From the output above we see my three K3s nodes with FQDN, status, role, age and version. So here k3node1 has the master role.

As an alternative, you can also execute the command in verbose mode:

kubectl get node -o wide
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Using ESXi on Arm as a tiny Kubernetes cluster

ESXi on Intel x86 architecture has been a commodity for many years now. In recent years and during VMworld for example we’ve seen early alpha versions of ESXi running on Arm architecture like smart NICs or even Raspberry Pi. Meanwhile VMware developers published a Fling named ESXi Arm Edition to deploy ESXi on Arm architecture. Of course this is a lab project and not supported by VMware for production workloads. But anyway, it’s a great opportunity to play around with ESXi on a cheap and tiny computer like Raspberry Pi. I will not explain how to deploy ESXi on Arm. Check the detailed documentation on the Fling project page (PDF). I will focus on day-2 operation.

I would like to thank William Lam for providing a lot of background information, hacks and tricks around PhotonOS and ESXionArm.

Now I’ve got an ESXi host on my Raspi. What can I do with it?

Just a few remarks before we start:

You can’t run any workload on the ESXi on Arm platform. As the project name says, it’s an Arm architecture, So you can’t run operating systems based on Intel architecture. All guest VMs need to be made for Arm architecture. That will rule out Windows guest systems and also most Linux distributions. But luckily there are a couple of Linux distributions made specific for Arm architecture like Ubuntu Server for Arm, or Photon OS. For my demonstration I chose the latest Photon OS (version 4 beta). As host hardware I’m using the “big” Raspberry Pi 4 with 8 GB RAM. You can imagine that 8 GB of RAM isn’t very much for host OS and guest VMs. We have to use resources sparingly.

Our aim is to deploy a 3 node Kubernets cluster on an ESXi on Arm host on Raspberry Pi with just 8 GB RAM and 4 cores. Sounds crazy, but it’s possible. Thanks to K3s lightweight Kubernetes on Arm.

Hardware used

  • Raspberry Pi 4, Broadcom BCM2711, Quad core Cortex-A72 (ARM v8) 64-bit SoC @ 1.5GHz
  • Heat sink for Raspberry Pi4 (your Raspi will become hot without)
  • SD-card (only for UEFI BIOS)
  • USB stick for ESXi installation
  • USB 3 hub with external power supply (Raspi doesn’t provide reliable power on USB port for an NVMe SSD)
  • USB 3 NVMe M.2 case
  • Samsung NVMe EvoPlus 250 GB M.2

Using ESXi on Arm in standalone mode

Although I have joined my ESXi on Raspi to my vCenter 7, I will not use any vCenter features. All works are done like on a standalone ESXi (with all the shortcomings and limitations).

First we need 3 VMs for the 3 K3s nodes. It’s a good idea to build a VM with everything we need except K3s and then clone it. Well, if you think cloning a VM on a standalone ESXi on Arm host is just a mouse click in the UI, then welcome to the real world. 😉 I will come to that point later. Let’s build our first Photon OS VM.

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