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Raspberry pi 4B kubernetes cluster

NULLX
I love opensource code. I love cooding. I love learning new things
Updated on ・3 min read

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 ⚡️

Cluster preview

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: https://github.com/nullxx/clusperry-installer.

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

SELECT OS

2. Configure each node with your configuration:

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

3. Download OS images

Download

4. Write images

Write images

5. Open generated images

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: https://github.com/k3s-io/k3s-ansible

Clone the repo

git clone https://github.com/k3s-io/k3s-ansible.git
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Get into the cloned repo

cd k3s-ansible
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Create our inventory from the sample

cp -R inventory/sample inventory/my-cluster
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Edit inventory/my-cluster/hosts.ini

nano inventory/my-cluster/hosts.ini
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[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
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Edit inventory/my-cluster/group_vars/all.yml

In my case edit the ansible_user to ubuntu

---
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: ""
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Be ready for the power!

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

ansible-playbook site.yml -i inventory/my-cluster/hosts.ini
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Install kubectl in your computer

In my case macOS

brew install kubectl
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Get the kubectl config from any of your master nodes

scp ubuntu@192.168.1.100:~/.kube/config ~/.kube/config
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Verify installation.

Check that all nodes are in STATUS 'Ready'

kubectl get nodes
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Deploy test

Create a local DNS entry for the test

sudo echo "192.168.1.100 test.com" >> /etc/hosts
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I'm going to use traefik because is installed by default with k3s.

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
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 Verify pods are up

kubectl get pods
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Go to http://test.com on your browser

curl http://test.com
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Its working!

Cleanup

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

Persistent storage

Part two available here

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