How to Set Up a K3S Cluster in 2025

#!/bin/bash

# Function to get user input with a default value
get_input() {
    local prompt=$1
    local default=$2
    local input
    read -p "$prompt [$default]: " input
    echo "${input:-$default}"
}

# Ask the user whether they want to create a template, deploy or destroy VMs
echo "Select an option:"
echo "1) Create Cloud-Init Template"
echo "2) Deploy VMs"
echo "3) Destroy VMs"
read -p "Enter your choice (1, 2, or 3): " ACTION

if [[ "$ACTION" != "1" && "$ACTION" != "2" && "$ACTION" != "3" ]]; then
    echo "❌ Invalid choice. Please run the script again and select 1, 2, or 3."
    exit 1
fi

# === OPTION 1: CREATE CLOUD-INIT TEMPLATE ===
120 collapsed lines
if [[ "$ACTION" == "1" ]]; then
    TEMPLATE_ID=$(get_input "Enter the template VM ID" "300")
    STORAGE=$(get_input "Enter the storage name" "local")
    TEMPLATE_NAME=$(get_input "Enter the template name" "ubuntu-cloud")
    IMG_URL="https://cloud-images.ubuntu.com/noble/current/noble-server-cloudimg-amd64.img"
    IMG_FILE="/root/noble-server-cloudimg-amd64.img"

    echo "📥 Downloading Ubuntu Cloud image for cloud-init setup..."
    cd /root
    wget -O $IMG_FILE $IMG_URL || { echo "❌ Failed to download the image"; exit 1; }

    echo "🖥️ Creating VM $TEMPLATE_ID..."
    qm create $TEMPLATE_ID --memory 2048 --cores 2 --name $TEMPLATE_NAME --net0 virtio,bridge=vmbr0

    echo "💾 Importing disk to storage ($STORAGE)..."
    qm disk import $TEMPLATE_ID $IMG_FILE $STORAGE || { echo "❌ Failed to import disk"; exit 1; }

    echo "🔗 Attaching disk..."
    qm set $TEMPLATE_ID --scsihw virtio-scsi-pci --scsi0 $STORAGE:vm-$TEMPLATE_ID-disk-0

    echo "☁️ Adding Cloud-Init drive..."
    qm set $TEMPLATE_ID --ide2 $STORAGE:cloudinit

    echo "🛠️ Configuring boot settings..."
    qm set $TEMPLATE_ID --boot c --bootdisk scsi0

    echo "🖧 Adding serial console..."
    qm set $TEMPLATE_ID --serial0 socket --vga serial0

    echo "📌 Converting VM to template..."
    qm template $TEMPLATE_ID

    echo "✅ Cloud-Init Template created successfully!"
    exit 0
fi

# === OPTION 2: DEPLOY VMs ===
if [[ "$ACTION" == "2" ]]; then
    TEMPLATE_ID=$(get_input "Enter the template VM ID" "300")
    START_ID=$(get_input "Enter the starting VM ID" "301")
    NUM_VMS=$(get_input "Enter the number of VMs to deploy" "6")
    STORAGE=$(get_input "Enter the storage name" "dataz2")
    IP_PREFIX=$(get_input "Enter the IP prefix (e.g., 10.57.57.)" "10.57.57.")
    IP_START=$(get_input "Enter the starting IP last octet" "30")
    GATEWAY=$(get_input "Enter the gateway IP" "10.57.57.1")
    DNS_SERVERS=$(get_input "Enter the DNS servers (space-separated)" "8.8.8.8 1.1.1.1")
    DOMAIN_SEARCH=$(get_input "Enter the search domain" "merox.dev")
    DISK_SIZE=$(get_input "Enter the disk size (e.g., 100G)" "100G")
    RAM_SIZE=$(get_input "Enter the RAM size in MB" "16384")
    CPU_CORES=$(get_input "Enter the number of CPU cores" "4")
    CPU_SOCKETS=$(get_input "Enter the number of CPU sockets" "4")
    SSH_KEY_PATH=$(get_input "Enter the SSH public key file path" "/root/.ssh/id_rsa.pub")

    if [[ ! -f "$SSH_KEY_PATH" ]]; then
        echo "❌ Error: SSH key file not found at $SSH_KEY_PATH"
        exit 1
    fi

    for i in $(seq 0 $((NUM_VMS - 1))); do
        VM_ID=$((START_ID + i))
        IP="$IP_PREFIX$((IP_START + i))/24"
        VM_NAME=$(get_input "Enter the name for VM $VM_ID" "ubuntu-vm-$((i+1))")

        echo "🔹 Creating VM: $VM_ID (Name: $VM_NAME, IP: $IP)"

        if qm status $VM_ID &>/dev/null; then
            echo "⚠️ VM $VM_ID already exists, removing..."
            qm stop $VM_ID &>/dev/null
            qm destroy $VM_ID
        fi

        if ! qm clone $TEMPLATE_ID $VM_ID --full --name $VM_NAME --storage $STORAGE; then
            echo "❌ Failed to clone VM $VM_ID, skipping..."
            continue
        fi

        qm set $VM_ID --memory $RAM_SIZE \
                      --cores $CPU_CORES \
                      --sockets $CPU_SOCKETS \
                      --cpu host \
                      --serial0 socket \
                      --vga serial0 \
                      --ipconfig0 ip=$IP,gw=$GATEWAY \
                      --nameserver "$DNS_SERVERS" \
                      --searchdomain "$DOMAIN_SEARCH" \
                      --sshkey "$SSH_KEY_PATH"

        qm set $VM_ID --delete ide2 || true
        qm set $VM_ID --ide2 $STORAGE:cloudinit,media=cdrom
        qm cloudinit update $VM_ID

        echo "🔄 Resizing disk to $DISK_SIZE..."
        qm resize $VM_ID scsi0 +$DISK_SIZE

        qm start $VM_ID
        echo "✅ VM $VM_ID ($VM_NAME) created and started!"
    done
    exit 0
fi

# === OPTION 3: DESTROY VMs ===
if [[ "$ACTION" == "3" ]]; then
    START_ID=$(get_input "Enter the starting VM ID to delete" "301")
    NUM_VMS=$(get_input "Enter the number of VMs to delete" "6")

    echo "⚠️ Destroying VMs from $START_ID to $((START_ID + NUM_VMS - 1))..."
    for i in $(seq 0 $((NUM_VMS - 1))); do
        VM_ID=$((START_ID + i))

        if qm status $VM_ID &>/dev/null; then
            echo "🛑 Stopping and destroying VM $VM_ID..."
            qm stop $VM_ID &>/dev/null
            qm destroy $VM_ID
        else
            echo "ℹ️ VM $VM_ID does not exist. Skipping..."
        fi
    done
    echo "✅ Specified VMs have been destroyed."
    exit 0
fi

1
[master]
2
10.57.57.30
3
10.57.57.31
4
10.57.57.32
5

6
[node]
7
10.57.57.33
8
10.57.57.34
9
10.57.57.35
10

11
[k3s_cluster:children]
12
master
13
node

1
---
2
apiVersion: v1
3
kind: Secret
4
metadata:
5
  name: traefik-dashboard-auth
6
  namespace: traefik
7
type: Opaque
8
data:
9
  users: abc123==

1
apiVersion: traefik.io/v1alpha1
2
kind: IngressRoute
3
metadata:
4
  name: rancher
5
  namespace: cattle-system
6
spec:
7
  entryPoints:
8
    - websecure
9
  routes:
10
    - match: Host(`rancher.k3s.your.domain`)
11
      kind: Rule
12
      services:
13
        - name: rancher
14
          port: 443
15
      middlewares:
16
        - name: default-headers
17
  tls:
18
    secretName: k3s-your-domain-tls

1
apiVersion: traefik.io/v1alpha1
2
kind: Middleware
3
metadata:
4
  name: longhorn-headers
5
  namespace: longhorn-system
6
spec:
7
  headers:
8
    customRequestHeaders:
9
      X-Forwarded-Proto: "https"

1
apiVersion: networking.k8s.io/v1
2
kind: Ingress
3
metadata:
4
  name: longhorn-ingress
5
  namespace: longhorn-system
6
  annotations:
7
    traefik.ingress.kubernetes.io/router.entrypoints: websecure
8
    traefik.ingress.kubernetes.io/router.tls: "true"
9
    traefik.ingress.kubernetes.io/router.middlewares: longhorn-system-longhorn-headers@kubernetescrd
10
spec:
11
  rules:
12
  - host: storage.k3s.your.domain
13
    http:
14
      paths:
15
      - path: /
16
        pathType: Prefix
17
        backend:
18
          service:
19
            name: longhorn-frontend
20
            port:
21
              number: 80
22
  tls:
23
  - hosts:
24
    - storage.k3s.your.domain
25
    secretName: k3s-your-domain-tls