Use Cloud-init yaml with Proxmox

Introduction

• https://pve.proxmox.com/wiki/Cloud-Init_Support
• https://cloud-init.io/
• https://pve.proxmox.com/pve-docs/qm.1.html

In order to use Cloud-init with Proxmox, the following steps are recommended:

1. Get a dedicated Cloud-init image for the Linux distribution.
2. Use this image to build a template VM.
3. Provision servers by cloning the template VM and mounting the Cloud-init configuration, so that it will be applied during startup.

Multiple ways to provide Cloud-init configuration exist in Proxmox, also via GUI. Most cloud providers do support yaml configuration files and this can be done in Proxmox as well - via Custom Cloud-Init Configuration.

Prerequisites

Storage:

1. LVM-thin storage pool: local-lvm
   • For thin provisioning, discard=on is recommended on disks and therefore set by the provisioning scripts. The guest OS must be configured to regularly run fstrim in order to clean up unused blocks - Debian does this by default, see systemctl status fstrim.timer: https://gist.github.com/hostberg/86bfaa81e50cc0666f1745e1897c0a56
2. Directory with cloudinit snippets: local
   • Snippets are not enabled by default and must be added in e.g. "Datacenter" -> "Storage" -> Edit: local.
   • In Proxmox clusters, these snippets must be accessible for all nodes in a shared storage, Link. - unless they are removed after provisioning

Networking:

1. Network interfaces with vlans

Additional information:

• Cloud-init configs for user data and networking must be split, as implemented by the provisioning script: qm set 9001 --cicustom "user=<volume>,network=<volume>,meta=<volume>"

Usage

# user@local:~#
git clone git@github.com:martipoe/proxmox-cloudinit-debian.git
cd proxmox-cloudinit-debian

All configuration changes should be committed to this repository and can then be reused for future rebuilds and migrations.

Create Template VM

Debian provides cloudinit-ready daily image builds at https://cloud.debian.org/images/cloud/bookworm/latest/. They only have a single root partition - creating templates with a partitioning schemes requires custom installations with preseeds, not implemented here.

The VM does not require networking, because we will not boot it.

Each Template VM needs its own subdirectory in ./template/${TEMPLATE_VM_NAME}/ with these files:

• .env

./template/${TEMPLATE_VM_NAME}/.env:

# source for cloudinit ready Debian Image
export TEMPLATE_IMAGE_URL="https://cloud.debian.org/images/cloud/bookworm/latest/"
# Cloudinit Image name
export TEMPLATE_IMAGE_NAME="debian-12-generic-amd64.qcow2"
# ID of the Template VM
export TEMPLATE_VM_ID=9001
# Name of the Template VM
export TEMPLATE_VM_NAME="cloudinit-template-debian-12"
# Storage of the Template VM
export TEMPLATE_STORAGE_NAME="local-lvm"
# Resources
export TEMPLATE_VM_MEM=512

# user@local:~#
rsync -avz --delete * proxmox.lan:proxmox-cloudinit-debian/

# root@proxmox:~#
cd proxmox-cloudinit-debian

# create template vm
bash ./1-template.sh debian-12

Provision a VM from the Template VM

Configs and .env for the provisioned VM in ./provision/docker-01 are exemplary.

Each VM needs its own subdirectory in ./provision/${PROVISION_VM_NAME}/ with these files:

• .env
• user-data
• network-config

./provision/${PROVISION_VM_NAME}/.env:

# ID from template/name/.env
export TEMPLATE_VM_ID=9001
# Storage directory used for cloudinit snippets
export PROVISION_CLOUDINIT_STORAGE_NAME="local"
export PROVISION_CLOUDINIT_STORAGE_PATH="/mnt/pve/local"
# ID of the VM
export PROVISION_VM_ID=9002
# Name of the VM
export PROVISION_VM_NAME="docker-01"
# Storage of the VM
export PROVISION_VM_STORAGE_NAME="local-lvm"
# Root disk size
export PROVISION_VM_ROOT_DISK_SIZE="10G"
# PROVISION_VM_DATA_DISK_MIGRATE_FROM_ID will attempt to import the data partition from the VM ID that has been created using this script
export PROVISION_VM_DATA_DISK_MIGRATE_FROM_ID=""
# Ignored if PROVISION_VM_DATA_DISK_MIGRATE_FROM_ID is set, otherwise a data disk of the specified size will be created
export PROVISION_VM_DATA_STORAGE_NAME="hdd-thin"
export PROVISION_VM_DATA_STORAGE_LV="${PROVISION_VM_DATA_STORAGE_NAME}"
export PROVISION_VM_DATA_STORAGE_VG="${PROVISION_VM_DATA_STORAGE_NAME}"
export PROVISION_VM_DATA_DISK_SIZE="2G"
# Resources
export PROVISION_VM_MEM_SIZE=2048
export PROVISION_VM_CORES=2
# Networking
export PROVISION_VM_NETWORKING="--net0 virtio,bridge=vmbr0,firewall=1,tag=4"

# user@local:~#
rsync -avz --delete * proxmox.lan:proxmox-cloudinit-debian/

# root@proxmox:~#
cd proxmox-cloudinit-debian

# provision from template vm
bash ./2-provision.sh docker-01

Inspired by

• https://github.com/chris2k20/proxmox-cloud-init