Deploying Kubernetes Using k3d, kubectl and Docker

Kubernetes makes managing container within cluster easier. For Docker user who has fewer resources, there is an alternative solution to install Kubernetes on their servers, namely k3d.

Install Kubernetes in Existing Docker Engine with k3d

k3d is a tool to install and manage Kubernetes cluster using existing Docker system.

for example:

k3d cluster create my-cluster-name \
    --api-port 127.0.0.1:40001 \
    --port "30000-30100:30000-30100@server:0" \
    --k3s-arg "--tls-san=127.0.0.1@server:0" \
    --volume /home/cluster-data:/mnt/cluster-data

k3d properties

Property	Value	Description
–volume	:	Mount folder to be used for cluster applications data
–api-port		Define static k8s API port
–port		Mount range of host ports into container ports
–k3s-arg		Arguments for k3s under k3d cluster

k3s properties

Property	Value	Description
–tls-san

Kubectl for Managing Kubernetes Cluster

Kubernetes Objects

Kubernetes objects are persistent entities that act as building blocks in the Kubernetes system ref.

Namespace

Secret

StorageClass

In k3d mounting pv manually to local-path is troublesome

PersistentVolume

Service

Service Object exposes the network of one or more Pods in the cluster.

Headless Service
NodePort Service

StatefulSet

StatefulSet is used to manage containers that use stateful state such as databases, object storages, and applications that need to mount persistent storage such as web apps.

Property	Value	Description
spec.template.spec.hostNetwork

PersistentVolumeClaim

Property	Value	Description
provisioner		Component responsible for automatically creating and managing storage resources
	rancher.io/local-path	Use local storage. No network overhead.
	kubernetes.io/no-provisioner	No dynamic provisioning.
	longhorn	Distributed block storage system for Kubernetes. Has network overhead.
volumeBindingMode

Config Map

Port Forwarding

Kubernetes Pods to VPS Host

Desktop to VPS Host using SSH Tunneling

SSH Tunneling is a cost effective part to to connect to the internal network of Kubernetes host server, and

#!/bin/bash

# Set your SSH user and remote host here
SSH_USER="your_ssh_user"
REMOTE_HOST="your_remote_host"

# Define your remote port forwarding configurations
# Format: "remote_port:local_address:local_port"
PORT_FORWARDINGS=(
    "9090:localhost:8080"   # Example: Forward remote port 9090 to local port 8080
    "9091:localhost:8081"   # Example: Forward remote port 9091 to local port 8081
    "9092:localhost:8082"   # Example: Forward remote port 9092 to local port 8082
)

# Generate the SSH command with all port forwardings
SSH_CMD="ssh"
for forwarding in "${PORT_FORWARDINGS[@]}"; do
    SSH_CMD+=" -R $forwarding"
done
SSH_CMD+=" $SSH_USER@$REMOTE_HOST"

# Prompt for SSH password and execute the SSH command
echo "Please enter your SSH password:"
read -s PASSWORD

# Use sshpass to supply the password to SSH
sshpass -p "$PASSWORD" $SSH_CMD

VPS Host to Cloudflare using Cloudflared

Forward Localhost Port to Internal IP Port

#!/bin/bash

# Get the internal IP of the node
INTERNAL_IP=$(kubectl get node -o=jsonpath='{.items[0].status.addresses[?(@.type=="InternalIP")].address}')

# Define an array of ports that you want to redirect
PORTS=(8529 5432 3306)  # Add as many ports as needed

# Loop through each port and update iptables rules
for PORT in "${PORTS[@]}"; do
    # Remove any existing iptables rule for the current port
    iptables -t nat -D OUTPUT -p tcp --dport $PORT -j DNAT --to-destination $INTERNAL_IP:$PORT 2>/dev/null
    
    # Add the new iptables rule for the current port
    iptables -t nat -A OUTPUT -p tcp --dport $PORT -j DNAT --to-destination $INTERNAL_IP:$PORT
done

Muhammad Insan Al-Amin