Setting up Cloud Init Ubuntu Image on Proxmox

Sat, 15 Oct 2022 00:00:00 +0000

This post shows a compact, repeatable flow for creating a Cloud-Init based Ubuntu template in Proxmox so you can spin up configured VMs quickly.

TL;DR:

Download an Ubuntu cloud image, import it into Proxmox, add a Cloud-Init drive, set boot order, convert to a template, then clone.

Prerequisites

A Proxmox VE host with LVM (or other writable storage like local-lvm)
SSH or shell access to your Proxmox host
A public SSH key (for injecting into cloud-init)

Quick checklist

Download cloud image
Create a small VM (temporary)
Import disk, attach to VM
Add cloud-init drive and configure user/ssh
Convert VM to template
Clone when needed

Step-by-step

1) Download the Ubuntu cloud image

Choose the release you prefer and download the cloud image. Example (Focal):

wget https://cloud-images.ubuntu.com/focal/current/focal-server-cloudimg-amd64.img

2) Create a temporary VM to attach the image to

Adjust memory and CPU to taste — this VM will become the template.

qm create 8000 --memory 2048 --core 2 --name ubuntu-cloud --net0 virtio,bridge=vmbr0

3) Import the cloud image into storage

Import the downloaded image into a Proxmox storage pool (example uses local-lvm):

qm importdisk 8000 focal-server-cloudimg-amd64.img local-lvm

4) Attach the imported disk to the VM (SCSI recommended)

qm set 8000 --scsihw virtio-scsi-pci --scsi0 local-lvm:vm-8000-disk-0

5) Add the Cloud-Init drive

qm set 8000 --ide2 local-lvm:cloudinit

6) Make the VM boot from the disk

qm set 8000 --boot c --bootdisk scsi0

7) Add a serial console (optional, helpful for headless debugging)

qm set 8000 --serial0 socket --vga serial0

Don’t Start Yet

Warning — do not start the VM yet. Configure cloud-init and hardware first. Starting too early can record IDs/state you may not want in your template.

8) Configure Cloud-Init fields (hostname, user, SSH key)

You can set these with the GUI or via qm set. Example CLI:

qm set 8000 --ciuser ubuntu --sshkey "$(cat ~/.ssh/id_rsa.pub)"
qm set 8000 --citype nocloud

If you want to provide a full user-data/meta-data payload for NoCloud, you can supply files or use Proxmox GUI fields.

9) Convert the VM to a template

qm template 8000

10) Clone the template whenever you need a new VM

qm clone 8000 135 --name yoshi

Tips

Resize disks after cloning if you need per-VM different sizes; keep the template small.
Put idempotent provisioning (Ansible, cloud-init modules) in the guest rather than baking many steps into the template.

Troubleshooting

If you accidentally booted a template (or need a fresh machine-id inside a guest):

sudo rm -f /etc/machine-id
sudo rm -f /var/lib/dbus/machine-id

Shutdown the VM and do not boot it; a new id will be generated on next boot. If it’s not generated automatically, run:

sudo systemd-machine-id-setup

If cloud-init doesn’t apply after cloning, verify the cloud-init datasource type and that Proxmox’s cloud-init fields are populated correctly for the new host.

Virtualization | Derek Armstrong — Staff Engineer & Solutions Architect

Setting up Cloud Init Ubuntu Image on Proxmox

Prerequisites

Quick checklist

Step-by-step

1) Download the Ubuntu cloud image

2) Create a temporary VM to attach the image to

3) Import the cloud image into storage

4) Attach the imported disk to the VM (SCSI recommended)

5) Add the Cloud-Init drive

6) Make the VM boot from the disk

7) Add a serial console (optional, helpful for headless debugging)

8) Configure Cloud-Init fields (hostname, user, SSH key)

9) Convert the VM to a template

10) Clone the template whenever you need a new VM

Tips

Troubleshooting