High Availability Raspberry Pi K8s Cluster

Introduction

For tech enthusiasts, a home-lab setup can be incredibly useful. A great option to consider is deploying a Kubernetes (k8s) cluster on Raspberry Pi, which offers an affordable and efficient solution. Here is what I did to set up a HA K8s cluster for myself.

Prerequisites

A domina name.
Three or more Raspberry Pi devices.
Ubuntu 24.04 OS flashed on each Pi.
Private home network.

Step-by-step Guide

For this guide, I assume you have the domain harrytang.com and three Pi devices with the private IPs of 192.168.68.51, 192.168.68.52 and 192.168.68.53.

Config static IP addresses:

Edit the /etc/netplan/50-cloud-init.yaml file with the following settings:

# /etc/netplan/50-cloud-init.yaml
network:
  ethernets:
    eth0:
      dhcp4: no
      addresses:
        - 192.168.68.51/22 # 22 is the CIDR notation for 255.255.252.0
      routes:
        - to: default
          via: 192.168.68.1
      nameservers:
        addresses:
          - 1.1.1.1
          - 1.0.0.1
          - 2606:4700:4700::1111
          - 2606:4700:4700::1001
      optional: true
  version: 2

Then, apply it and do the same for the other two devices:

sudo netplan try
sudo netplan apply

Install required packages (do this for all Pi devices):

sudo apt-get update && sudo apt-get upgrade -y
sudo apt-get install -y net-tools iputils-ping ufw vim socat

Enable kernel modules and IP forwarding (do this for all Pi devices):

cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
br_netfilter
overlay
EOF
sudo modprobe br_netfilter
sudo modprobe overlay

cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.ipv4.ip_forward=1
net.ipv6.conf.all.forwarding=1
EOF
sudo sysctl --system

Configure the firewall (do this for all Pi devices):

sudo ufw allow ssh
sudo ufw default allow routed # Allow routed traffic
sudo ufw allow from 192.168.0.0/16 # Allow traffic from private network
sudo ufw allow from fe80::/10 # Allow traffic from private network
sudo ufw enable
sudo ufw status verbose

Install Kubernetes components and CRI-O (do this for all Pi devices):

kubernetes_version=v1.31
crio_version="$kubernetes_version"

# Add Kubernetes and CRI-O apt repositories
curl -fsSL "https://pkgs.k8s.io/core:/stable:/$kubernetes_version/deb/Release.key" \
    | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
echo "deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/$kubernetes_version/deb/ /" \
    | sudo tee /etc/apt/sources.list.d/kubernetes.list

curl -fsSL "https://pkgs.k8s.io/addons:/cri-o:/stable:/$crio_version/deb/Release.key" \
    | sudo gpg --dearmor -o /etc/apt/keyrings/cri-o-apt-keyring.gpg
echo "deb [signed-by=/etc/apt/keyrings/cri-o-apt-keyring.gpg] https://pkgs.k8s.io/addons:/cri-o:/stable:/$crio_version/deb/ /" \
    | sudo tee /etc/apt/sources.list.d/cri-o.list

# Install Kubernetes and CRI-O packages
sudo apt-get update
k8s_version=$(apt-cache madison kubeadm | awk '{print $3}' | head -1)
crio_version=$(apt-cache madison cri-o | awk '{print $3}' | head -1)
sudo apt-get install -y kubeadm="$k8s_version" kubelet="$k8s_version" kubectl="$k8s_version" cri-o="$crio_version"
sudo apt-mark hold kubeadm kubelet kubectl cri-o
sudo systemctl enable --now crio

Generate the Encryption Configuration file for encryption at rest:

Add more secure to your K8s cluster by using encryption at rest, follow this guide to generate the /etc/kubernetes/enc/enc.yaml file.
Configure domain for K8s API endpoint:

Go to your domain panel and add a A Record of k8s.harrytang.com point to the first Pi device, e.g 192.168.68.51:
```
k8s.harrytang.com.      300     IN      A       192.168.68.51
```

From the first Pi, initializes a Kubernetes control-plane node:

Create the init-config.yaml file:

apiVersion: kubeadm.k8s.io/v1beta3
kind: ClusterConfiguration
controlPlaneEndpoint: 'k8s.harrytang.com:6443'
etcd:
  local:
    extraArgs:
      listen-metrics-urls: http://0.0.0.0:2381
controllerManager:
  extraArgs:
    bind-address: '0.0.0.0'
scheduler:
  extraArgs:
    bind-address: '0.0.0.0'
networking:
  podSubnet: 10.1.0.0/16,fd01::/64
  serviceSubnet: 10.96.0.0/16,fd98::/108
apiServer:
  extraArgs:
    encryption-provider-config: /etc/kubernetes/enc/enc.yaml
  certSANs:
    - 'k8s.harrytang.com'
  extraVolumes:
    - name: enc
      hostPath: /etc/kubernetes/enc
      mountPath: /etc/kubernetes/enc
      pathType: DirectoryOrCreate
      readOnly: true
---
apiVersion: kubeadm.k8s.io/v1beta3
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 192.168.68.51
  bindPort: 6443
nodeRegistration:
  kubeletExtraArgs:
    node-ip: 192.168.68.51
---
apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
serverTLSBootstrap: true
---
apiVersion: kubeproxy.config.k8s.io/v1alpha1
kind: KubeProxyConfiguration
metricsBindAddress: '0.0.0.0:10249'

Then, run:

sudo kubeadm config images pull
sudo kubeadm init phase preflight
sudo kubeadm init --config=init-config.yaml --upload-certs

Next, deploy the Calico networking for the cluster:

kubectl create -f https://raw.githubusercontent.com/projectcalico/calico/v3.28.2/manifests/tigera-operator.yaml

Create the calico.yaml:

apiVersion: operator.tigera.io/v1
kind: Installation
metadata:
  name: default
spec:
  # Configures Calico networking.
  calicoNetwork:
    # Note: The ipPools section cannot be modified post-install.
    ipPools:
      - blockSize: 26
        cidr: 10.1.0.0/16
        encapsulation: VXLAN # Use this for Oracle Cloud Ubuntu 22.04
        natOutgoing: Enabled
        nodeSelector: all()
      - blockSize: 122
        cidr: fd01::/64
        encapsulation: None
        natOutgoing: Enabled
        nodeSelector: all()

---
# This section configures the Calico API server.
# For more information, see: https://projectcalico.docs.tigera.io/master/reference/installation/api#operator.tigera.io/v1.APIServer
apiVersion: operator.tigera.io/v1
kind: APIServer
metadata:
  name: default
spec: {}

Then, apply it:

kubectl create -f calico.yaml

Finally, reboot the Pi for Calio to configure the network properly:

sudo reboot

## Check if all good
kubectl get pods -A
NAMESPACE         NAME                                       READY   STATUS    RESTARTS   AGE
calico-system     calico-kube-controllers-598654fc5f-2tj82   1/1     Running   2          4m39s
calico-system     calico-node-zmq2r                          1/1     Running   1          4m39s
calico-system     calico-typha-7d99f69485-8qjr2              1/1     Running   1          4m40s
calico-system     csi-node-driver-xfngl                      2/2     Running   2          4m39s
kube-system       coredns-7c65d6cfc9-756vf                   1/1     Running   1          15m
kube-system       coredns-7c65d6cfc9-p8rc2                   1/1     Running   1          15m
kube-system       etcd-pi1                                   1/1     Running   1          15m
kube-system       kube-apiserver-pi1                         1/1     Running   1          15m
kube-system       kube-controller-manager-pi1                1/1     Running   1          15m
kube-system       kube-proxy-6dnbm                           1/1     Running   1          15m
kube-system       kube-scheduler-pi1                         1/1     Running   1          15m
tigera-operator   tigera-operator-89c775547-xbf9j            1/1     Running   1          5m45s

Join the other two Pi devices as control-plane to form a High-availability cluster:

Create the cp-config.yaml file:

apiVersion: kubeadm.k8s.io/v1beta4
kind: JoinConfiguration
caCertPath: /etc/kubernetes/pki/ca.crt
controlPlane:
  certificateKey: q1w2e3r4t5y6u7i8o9p0 # replace this
  localAPIEndpoint:
    advertiseAddress: 192.168.68.52 #  192.168.68.53 for the 3rd device
    bindPort: 6443
discovery:
  bootstrapToken:
    apiServerEndpoint: k8s.harrytang.com:6443
    caCertHashes:
      - sha256:0p9o8i7u6y5t4r3e2w1q # replace this
    token: werwerw.qweertytyudfgsdf # replace this
  tlsBootstrapToken: werwerw.qweertytyudfgsdf # replace this
nodeRegistration:
  kubeletExtraArgs:
    - name: node-ip
      value: 192.168.68.52 #  192.168.68.53 for the 3rd device

And run the join command:

sudo kubeadm join --config=cp-config.yaml

Update the K8s API endpoint with the remaining two IP addresses.

k8s.harrytang.com.      300     IN      A       192.168.68.51
k8s.harrytang.com.      300     IN      A       192.168.68.52
k8s.harrytang.com.      300     IN      A       192.168.68.53

Verify and configure the control-plane nodes to treat them like worker nodes so they can start accepting pods:

kubectl get nodes
NAME   STATUS     ROLES           AGE     VERSION
pi1    Ready      control-plane   4h21m   v1.31.2
pi2    Ready      control-plane   3h45m   v1.31.2
pi3    Ready      control-plane   3h51m   v1.31.2    
kubectl taint nodes --all node-role.kubernetes.io/control-plane-

Conclusion

Well done on setting up a Kubernetes (K8s) system for your home-lab! Now, you’re ready to install any applications you want on it.

High Availability Raspberry Pi K8s Cluster

Introduction

Prerequisites

Step-by-step Guide

Conclusion

References

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