Raspberry pi 4B kubernetes cluster

I love decentralized computing. It’s beautiful. Just add a node to your cluster if you need more power! Just that. Restart the pods with no downtime, horizontal pod autoscaler...

To create a cluster, we can do it with services provided by google, amazon… or just manually installing it in each node.

I prefer to create my own mini cluster. My cluster is made of 6 raspberry pi 4B (4GB RAM each) and has it's own name: clusperry ⚡️

I created a simple gui tool to generate the linux images to flash into the mini-SD cards with the initial cloudconfig. You can check it here:

Nodes setup

Download the release from https://github.com/nullxx/clusperry-installer/releases/ (its currently only compiled for macOS)

1. Select the nodes operating system

2. Configure each node with your configuration:

• IP
• WIFI (or ethernet)
• hostname
• SSH keys

3. Download OS images

4. Write images

5. Open generated images

Install kubernetes with k3s

For this I will use ansible. It makes it easier to do all the install work. I will use the following repo:

Clone the repo

bash
git clone https://github.com/k3s-io/k3s-ansible.git

Get into the cloned repo

bash
cd k3s-ansible

Create our inventory from the sample

bash
cp -R inventory/sample inventory/my-cluster

Edit inventory/my-cluster/hosts.ini

bash
nano inventory/my-cluster/hosts.ini

ini
[master]
192.168.1.100
[node]
192.168.1.101
192.168.1.102
192.168.1.103
192.168.1.104
192.168.1.105
[k3s_cluster:children]
master
node

Edit inventory/my-cluster/group_vars/all.yml

In my case edit the ansible_user to ubuntu

yaml
---
k3s_version: v1.17.5+k3s1
ansible_user: ubuntu
systemd_dir: /etc/systemd/system
master_ip: "{{ hostvars[groups['master'][0]]['ansible_host'] | default(groups['master'][0]) }}"
extra_server_args: ""
extra_agent_args: ""

Be ready for the power!

Execute the ansible-playbook to install k8s in the nodes.

bash
ansible-playbook site.yml -i inventory/my-cluster/hosts.ini

Install kubectl in your computer

In my case macOS

bash
brew install kubectl

Get the kubectl config from any of your master nodes

bash
scp [email protected]:~/.kube/config ~/.kube/config

Verify installation.

Check that all nodes are in STATUS 'Ready'

bash
kubectl get nodes

Deploy test

Create a local DNS entry for the test

bash
sudo echo "192.168.1.100 test.com" >> /etc/hosts

I'm going to use traefik because is installed by default with k3s.

yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 2 # tells deployment to run 2 pods matching the template
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
  labels:
    name: nginx-service
spec:
  ports:
    - port: 80
      name: http
  selector:
    name: nginx-deployment
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: nginx-ingress
  annotations:
    kubernetes.io/ingress.class: traefik
spec:
  rules:
  - host: "test.com"
    http:
      paths:
      - path: /
        backend:
          serviceName: nginx-service
          servicePort: 80

Verify pods are up

kubectl get pods

Go to http://test.com on your browser

curl http://test.com

Its working!

Cleanup

Remember to remove the test.com line in /etc/hosts