Skip to content

vm-cloud-init-template.md

Latest commit

 

History

History
192 lines (136 loc) · 5.46 KB

vm-cloud-init-template.md

File metadata and controls

192 lines (136 loc) · 5.46 KB
Raw

Create Cloud-Init VM Template

Proxmox can use cloud images meant for OpenStack.

When the VM is started for the first time, the cloud-init inside the VM can initialize and configure the VM with the predefined network settings, SSH keys, and more.

Create a Cloud-Init Debian 12 Bookworm VM Template

Download cloud image

Proxmox uses a KVM (Kernel-based Virtual Machine) so there is no need to download images meant for physical hardware.

For example, when downloading Debian cloud images, genericcloud is enough for Proxmox. generic has drivers for bare metal installations that are not required.

qcow2 (Quick Copy-On-Write) images are intended to be used as the root filesystem of a virtual machine.

iso images are used as installation media and require manual setup process.

Download debian-12-genericcloud-amd64.qcow2 image for Debian 12.

There are no iso images available, so download the qcow2 image from https://cdimage.debian.org/images/cloud/bookworm/latest/

cd /var/lib/vz/template/iso
wget https://cdimage.debian.org/images/cloud/bookworm/latest/debian-12-genericcloud-amd64.qcow2

Install packages on the cloud image

Update the downloaded cloud image to include qemu-guest-agent to make it easier for the hypervisor to communicate with the VM.

Caution

It is generally recommended to install packages after a VM boots and completes the cloud-init initialization step.

Installing packages directly to the qcow2 image causes /etc/machine-id to be generated.

This creates issues like the DHCP server assigning the same IP address to every clone created from the template since they all have the same machine-id.

Deleting the contents of /etc/machine-id after installing the package has fixed the issue here.

apt install -y libguestfs-tools
virt-customize -a debian-12-genericcloud-amd64.qcow2 --install qemu-guest-agent
virt-customize -a debian-12-genericcloud-amd64.qcow2 --truncate /etc/machine-id

Terminal output

root@optiplex:/var/lib/vz/template/iso# virt-customize -a debian-12-genericcloud-amd64.qcow2 --install qemu-guest-agent
[   0.0] Examining the guest ...
[   7.4] Setting a random seed
virt-customize: warning: random seed could not be set for this type of 
guest
[   7.4] Setting the machine ID in /etc/machine-id
[   7.4] Installing packages: qemu-guest-agent
[  17.5] Finishing off
root@optiplex:/var/lib/vz/template/iso# 
root@optiplex:/var/lib/vz/template/iso# virt-customize -a debian-12-genericcloud-amd64.qcow2 --truncate /etc/machine-id
[   0.0] Examining the guest ...
[   3.4] Setting a random seed
virt-customize: warning: random seed could not be set for this type of 
guest
[   3.5] Truncating: /etc/machine-id
[   3.5] Finishing off
root@optiplex:/var/lib/vz/template/iso#

Create the VM

Create a new VM debian-12-cloud with VirtIO SCSI controller.

qm create 1000 \
    --memory 2048 --core 2 \
    --name debian-12-cloud \
    --net0 virtio,bridge=vmbr0

Set VM parameters

Import the downloaded image to local-lvm storage, attaching it as a SCSI drive. Similar to plugging in a hard drive to the motherboard SCSI port 0.

Enable SSD emulation in case the underlying disk is an SSD or NVMe. Enables TRIM support with discard.

Setting the SCSI Controller to 'VirtIO SCSI single' and enabling I/O Threads provide the best disk performance. [2]

qm set 1000 \
    --scsihw virtio-scsi-single \
    --scsi0 local-lvm:0,import-from=/var/lib/vz/template/iso/debian-12-genericcloud-amd64.qcow2,ssd=1,discard=on,iothread=1

Add Cloud-Init CD-ROM drive to to pass Cloud-Init data to the VM. Similar to attaching a CD-ROM drive with cloudinit disk inserted.

qm set 1000 --ide2 local-lvm:cloudinit

Restrict BIOS to boot from Cloud-Init image in the SCSCI port 0 only. Speeds up booting because VM BIOS skips testing for bootable CD-ROM.

qm set 1000 --boot order=scsi0

Allows the VMs to get all the CPU's instruction set and capabilities instead of using a virtualized setup. Reduces portability (live migration between nodes) but generally provides better performance.

qm set 1000 --cpu host

Configure serial console to use as a display. Equivalent to plugging in a VGA monitor to the VM.

qm set 1000 \
    --serial0 socket \
    --vga serial0

Enable QEMU Guest Agent

qm set 1000 --agent enabled=1

Set cloud-init parameters

Set Cloud-Init username and password

qm set 1000 --ciuser debian
qm set 1000 --cipassword $(openssl passwd -6 "bookworm")

Set Cloud-Init SSH keys

qm set 1000 --sshkeys /root/.ssh/id_rsa.pub

Set DHCP for the VM's network interface

qm set 1000 --ipconfig0 ip=dhcp

Create template

Convert to created VM into a template

qm template 1000

Create a new VM from template

qm clone <vm_template_id> <vm_id> --name <vm_name> --full
qm clone 1000 200 --name debian --full
qm start 200

If the image did not have qemu-guest-agent installed using virt-customize, install qemu-guest-agent after the VM boots up and cloud-init has completed initialization. Make sure to enable QEMU Guest Agent in the Options menu as well.

sudo apt install qemu-guest-agent

References

[1] https://pve.proxmox.com/wiki/Cloud-Init_Support

[2] https://kb.blockbridge.com/technote/proxmox-aio-vs-iouring/