Create Proxmox Ubuntu Cloud Init Template

Create Proxmox Ubuntu Cloud Init Template with Cloud-Init configuration for automated VM provisioning

Overview

Cloud-Init is a powerful cloud instance initialization framework that automates the configuration of instances during boot. In Proxmox VE, Cloud-Init enables templated VM deployment with automatic user provisioning, SSH key configuration, network setup, and custom initialization scripts. This approach is industry-standard for Infrastructure as Code (IaC) workflows and significantly reduces manual VM configuration time.

Key Benefits of Cloud-Init in Proxmox

Automated Provisioning: Configure VMs at boot time without manual intervention
Reproducibility: Create consistent instances across multiple deployments
Scalability: Easily provision multiple VMs with identical configurations
Security: Manage SSH keys and user credentials programmatically
Network Configuration: Automatically configure network interfaces and DNS settings
Custom Initialization: Run arbitrary scripts or commands during first boot

Creating the Cloud-Init Template

Step 1: Download Ubuntu Cloud Image

bash

1wget https://cloud-images.ubuntu.com/noble/current/noble-server-cloudimg-amd64.img
2qm create 8000 --memory 2048 --core 2 --name ubuntu-cloud --net0 virtio,bridge=vmbr0
3qm disk import 8000 noble-server-cloudimg-amd64.img local-lvm
4qm set 8000 --scsihw virtio-scsi-pci --scsi0 local-lvm:vm-8000-disk-0
5qm set 8000 --ide2 local-lvm:cloudinit
6qm set 8000 --boot c --bootdisk scsi0
7qm set 8000 --serial0 socket --vga serial0
8qm template 8000
9qm clone 8000 135 --name ubuntu-cloud --full

Technical Details of Each Step

Download Stage

The official Ubuntu cloud images from Canonical are optimized for cloud deployments. They contain:

Minimal filesystem (reduced bloat compared to standard ISOs)
Pre-installed Cloud-Init agent
Network device drivers optimized for hypervisors (virtio)
No package manager cached data to minimize image size

Available Ubuntu Versions: focal (20.04 LTS), jammy (22.04 LTS), noble (24.04 LTS), oracular (24.10)

VM Creation (qm create)

--memory 2048   : Base memory allocation in MB (can be adjusted per deployment)
--core 2        : CPU cores (scales with workload requirements)
--name          : Logical identifier for the template
--net0          : Network configuration (virtio driver for performance, vmbr0 = bridge)

Disk Import (qm disk import)

This step converts the downloaded cloud image to Proxmox's storage format:

Imports into local-lvm storage backend
Creates a dedicated volume for the VM
Initializes the disk with proper permissions and metadata

Storage Configuration (qm set --scsihw)

--scsihw virtio-scsi-pci : SCSI controller (modern alternative to IDE)
--scsi0 local-lvm:...    : Primary disk assignment using virtio-scsi

Performance Note: virtio-scsi provides better performance and scalability compared to IDE, supporting hot-plug operations and higher IOPS.

Cloud-Init ISO Setup (--ide2)

--ide2 local-lvm:cloudinit : IDE channel 2 for Cloud-Init data disk

This creates a read-only CD-ROM containing Cloud-Init metadata, user-data, and vendor-data. The Cloud-Init agent inside the VM reads this during boot.

Boot Configuration

--boot c              : Boot order (c = disk, n = network, a = floppy, d = cdrom)
--bootdisk scsi0      : Designate primary boot disk
--serial0 socket      : Serial console for troubleshooting (essential for headless VMs)
--vga serial0         : Direct console output to serial port

Template Conversion

qm template 8000 : Converts VM to template (disables further direct modifications)

Templates in Proxmox are read-only VMs that serve as base images for cloning. This prevents accidental modifications to the base configuration.

Cloning from Template

Full Clone vs. Linked Clone

The provided command uses --full to create a full clone (independent copy of all disk data):

bash

1qm clone 8000 135 --name ubuntu-cloud --full

Full Clone:

Independent disk copy (complete storage isolation)
Higher storage overhead (~2GB+ per clone)
Better for production VMs that require stability
No dependency on parent template

Linked Clone (without --full):

bash

1qm clone 8000 135 --name ubuntu-cloud

Shared backing data with copy-on-write (CoW)
~90% storage savings
Faster clone creation
Suitable for development/testing
Lower performance compared to full clones

Cloud-Init Configuration Options

After cloning, you can customize Cloud-Init behavior using these parameters:

User Configuration

bash

1qm set 135 --ciuser ubuntu --cipassword password123

ciuser: Specifies which user account should receive SSH keys and password configuration. Default depends on image (ubuntu for Ubuntu images, debian for Debian, etc.)

Network Configuration

bash

1qm set 135 --ipconfig0 ip=192.168.1.100/24,gw=192.168.1.1
2qm set 135 --ipconfig1 ip=192.168.2.100/24

ipconfig: Static IP configuration in netplan/cloud-init format:

ip=<address>/<cidr> : IPv4 address and netmask
gw=<gateway> : Default gateway
ip6=<address>/<cidr> : IPv6 configuration
ip6gw=<gateway> : IPv6 gateway

Custom Cloud-Init Script

bash

1qm set 135 --cicustom "user=local:snippets/custom-cloud-init.yaml"

This allows injecting custom initialization logic (package installation, service configuration, etc.)

Hostname and Domain Configuration

bash

1qm set 135 --hostname prod-app-01 --searchdomain example.com

Verification Commands

After creating the template, verify its configuration:

bash

1# List template details
2qm config 8000
3
4# Show template status
5qm status 8000
6
7# List all clones from this template
8qm list | grep -E "^[0-9]+" | awk '{print $1, $2}' | grep -v "8000"
9
10# Verify Cloud-Init disk attachment
11qm config 8000 | grep ide2