Alex Ellis

Here’s something you can do before work, with your morning coffee, or whilst waiting for dinner to cook of an evening. And there’s never been a better time to install Kubernetes to a Raspberry Pi, with the price-drop on the 2GB model — perfect for containers.

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You can buy a single RPi and still have a lot of fun, here I bought 4x 2GB nodes

I’ll show you how to install Kubernetes to your Raspberry Pi in 15 minutes including monitoring and how to deploy containers.

Updates: Dec 2020 — added cmdline.txt instructions for cgroups and ssh-copy-id.

The bill of materials

I’ll keep this quite simple.

  • Raspberry Pi 4, with 2GB or 4GB RAM — the 2GB is the best value, 4GB is best if you don’t plan on doing clustering.
  • SD card — 32GB recommended, larger is up to you, but Kubernetes writes to disk a lot and could kill a card, so I tend to prefer buying more smaller cards.
  • Power supply — you need the official supply, I know it’s expensive, but that’s for a reason. Don’t be cheap because you’ll buy twice.

If you’d like some links, you can find them in my home-lab post: Kubernetes Homelab with Raspberry Pi and k3sup.

Flash the initial OS

There are so many ways to install an Operating System, but I recommend Raspbian and the Lite edition which ships without a UI.

Once you download the image, you can use Etcher.io from our friends at Balena to flash it without even unzipping it. How cool is that?

Before you boot up that RPi, make sure you create a file named ssh in the boot partition. If on a Mac you’ll see that gets mounted for you as soon as you eject and re-insert the SD card.

Connect for the first boot

Now connect to the Raspberry Pi over your local network, it will show up as raspberry.local, but if you can’t connect for some reason, then install nmap and run nmap -sP 192.168.0.0/24 to run a network scan.

  • Change the password with passwd pi.
  • Run raspi-config and change the memory split to 16mb, so that we have all the RAM for Kubernetes, believe me, it needs it.

There’s one more change that’s essential for k3s. Add the following to /boot/cmdline.txt, but make sure that you don’t add new lines.

cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory

Copy or create an SSH key

k3sup uses password-less login by default, so that means you can run it from a script or automation without human intervention.

Copy your SSH key to the Raspberry Pi with:

ssh-copy-id pi@raspberrypi.local

If you have no SSH key on your local computer yet, then run ssh-keygen

Get your CLI tools

You do not need to log into your Raspberry Pi again. All tools will be installed on your client (i.e. your laptop) and the RPi will be accessed remotely as a server.

  • arkade — a hassle-free way to get Kubernetes apps and CLIs
  • kubectl — the Kubernetes CLI
  • k3sup — the Kubernetes (k3s) installer that uses SSH to bootstrap Kubernetes

arkade is a portable Kubernetes marketplace which makes it easy to install around 40 apps to your cluster, without worrying about all the gory details and configuration options. arkade also “does the right thing” for instance:

  • An app like OpenFaaS uses a helm chart
  • A tool like the Kubernetes dashboard only uses plain YAML manifests
  • Linkerd for example prefers to use a CLI

arkade abstracts that all away from the user with around 40 apps on offer. On top of that, if an app like Istio is known not to work on your device, it will block you from doing the wrong thing.

We can also use it to download k3sup and kubectl:

curl -sSL https://dl.get-arkade.dev | sudo sh

arkade get kubectl

arkade get k3sup

Did you know that you can also specify a version to arkade get? For example: arkade get kubectl --version 1.19.5

k3sup install can be used to install k3s as a server, to begin a new single-node cluster (that’s what we’ll do today). If you have multiple nodes, then the k3sup join command lets you add in additional agents or workers to expand the capacity.

Install Kubernetes with k3sup and k3s

k3s is a lightweight edition of Kubernetes made by Rancher Labs, it’s suitable for production, but also perfect for small devices like our Raspberry Pi. Its memory requirements are around 500MB for a server vs. around 2GB for kubeadm (upstream Kubernetes)

export IP="192.168.0.1" # find from ifconfig on RPi

k3sup install --ip $IP --user pi

In a few moments you’ll receive a kubeconfig file into your local directory, with an instruction on how to use it.

Find the node, and check if it’s ready yet

export KUBECONFIG=`pwd`/kubeconfig

kubectl get node -o wide

You can add -w to most kubectl commands to “watch” or “stream” the output status, so you can save on typing.

By default k3s comes with the metrics-server, which is used for Pod autoscaling and getting memory/CPU for pods and nodes:

kubectl top node

kubectl top pod --all-namespaces

Now let’s install one or two apps, run arkade install to see what’s available, but not that not all projects in the CNCF landscape work on ARM devices.

arkade install --helpAvailable Commands: argocd                  Install argocd

cert-manager Install cert-manager

chart Install the specified helm chart

consul-connect Install Consul Service Mesh

cron-connector Install cron-connector for OpenFaaS

crossplane Install Crossplane

docker-registry Install a Docker registry

docker-registry-ingress Install registry ingress with TLS

gitea Install gitea

gitlab Install GitLab

grafana Install grafana

info Find info about a Kubernetes app

ingress-nginx Install ingress-nginx

ingress-nginx Install ingress-nginx

inlets-operator Install inlets-operator

istio Install istio

jenkins Install jenkins

kafka-connector Install kafka-connector for OpenFaaS

kong-ingress Install kong-ingress for OpenFaaS

kube-image-prefetch Install kube-image-prefetch

kube-state-metrics Install kube-state-metrics

kubernetes-dashboard Install kubernetes-dashboard

linkerd Install linkerd

loki Install Loki for monitoring and tracing

metrics-server Install metrics-server

minio Install minio

mongodb Install mongodb

nats-connector Install OpenFaaS connector for NATS

nfs-client-provisioner Install nfs client provisioner

nginx-inc Install nginx-inc for OpenFaaS

openfaas Install openfaas

openfaas-ingress Install openfaas ingress with TLS

openfaas-loki Install Loki-OpenFaaS and Configure Loki logs provider for OpenFaaS

osm Install osm

portainer Install portainer to visualise and manage containers

postgresql Install postgresql

redis Install redis

registry-creds Install registry-creds

sealed-secrets Install sealed-secrets

tekton Install Tekton pipelines and dashboard

traefik2 Install traefik2

Let’s try the Kubernetes dashboard?

arkade install kubernetes-dashboard

The installation script prints out how to use the app, and arkade info can show us the same information later too.

#To forward the dashboard to your local machinekubectl proxy#To get your Token for logging inkubectl -n kubernetes-dashboard describe secret $(kubectl -n kubernetes-dashboard get secret | grep admin-user-token | awk '{print $1}')# Once Proxying you can navigate to the belowhttp://localhost:8001/api/v1/namespaces/kubernetes-dashboard/services/https:kubernetes-dashboard:/proxy/#/login

Paste in your token

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Now enjoy the dashboard:

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Let’s install another popular application, openfaas. OpenFaaS gives us a simple way to deploy functions and microservices to Kubernetes with built-in auto-scaling.

arkade get faas-cli

arkade install openfaas

Log in using the post-installation information.

The IP of my RPi is 192.168.0.201, so I can access OpenFaaS using a NodePort of 31112.

PASSWORD=$(kubectl get secret -n openfaas basic-auth -o jsonpath="{.data.basic-auth-password}" | base64 --decode; echo)export OPENFAAS_URL=http://192.168.0.201:31112echo -n $PASSWORD | faas-cli login --username admin --password-stdinfaas-cli store list --platform armhf

faas-cli store deploy figlet --platform armhf

faas-cli list

Now open the OpenFaaS UI and check your figlet function using http://192.168.0.201:31112 or the equivalent.

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You can also build your own functions with Python, Go, JavaScript and many other languages.

If you have a Docker Hub login, then you can try the following, but you’ll need to run it on a separate Raspberry Pi, with docker installed (curl -sSL https://get.docker.com | sudo sh)

export USERNAME=alexellis2

docker login -u $USERNAME
faas-cli template store pull golang-http

faas-cli new --lang golang-http --prefix=$USERNAME my-api
faas-cli up -f my-api.yml# Now invoke your functionfaas-cli invoke my-api -f my-api.yml

You can also edit the function’s code and then run faas-cli up again:

Contents of: my-api/handler.go

package functionimport (

"net/http"

"github.com/openfaas-incubator/go-function-sdk"

)
func Handle(req handler.Request) (handler.Response, error) {

return handler.Response{
Body: []byte(`Run k3s on your RPi!`),

StatusCode: http.StatusOK,

}, nil

}

Find out more about OpenFaaS at openfaas.com

You can also see your functions on the Kubernetes Dashboard:

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Get a public IP for your cluster

You can get a public IP for your cluster via a tunnel using the popular Open Source project inlets.

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Self-host websites and APIs

Wrapping up and next steps

If you want to take things further, you can start adding additional nodes into the cluster, to extend its capacity and to give redundancy.

You can connect with the OpenFaaS community — to talk about Kubernetes, ARM, Raspberry Pi clusters and serverless. Join our Slack workspace today.

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