cloudinit Module

Generates Cloud-init ISO disks for Linux and VyOS virtual machines, based on OS-specific templates.

Responsibility

This module:

• Renders three configuration files per VM:

  • user-data
  • meta-data
  • network-config

• Generates a temporary disk using libvirt_cloudinit_disk

• Persists this disk as a Libvirt volume in the specified storage pool (<vm_name>-cloudinit.iso)

What this module does not do

• Validate whether os_type is "linux" or "vyos" — it will fail if the template does not exist
• Filter VMs by type — expects the caller to handle this
• Handle Windows VMs — they must not be passed to this module
• Ensure network fields are complete — this is the responsibility of the templates

Expected Input

The vms variable must be a map where each VM contains:

Field	Type	Required	Notes
os_type	string	Yes	Must be "linux" or "vyos"
hostname	string	Yes	Used in meta-data and user-data
ssh_public	object	Yes	Includes type, key, host_origin
networks	list(object)	Yes	Same structure used in vm.auto.tfvars

⚠️ Critical requirement: Templates must exist in:

• templates/linux/
• templates/vyos/ Otherwise, Terraform will fail with "template not found".

Template Structure

The module expects the following files:

templates/
├── linux/
│   ├── user-data.yaml.tftpl
│   ├── meta-data.yaml.tftpl
│   └── network-config.yaml.tftpl
└── vyos/
    ├── user-data.yaml.tftpl
    ├── meta-data.yaml.tftpl
    └── network-config.yaml.tftpl

Each template receives exactly the data provided in vms[*]. Therefore, it must handle optional fields (e.g., ipv4_address == null → configure DHCP).

Example Usage

locals {
  cloudinit_vms = {
    for name, vm in var.vms : name => vm
    if vm.os_type == "linux" || vm.os_type == "vyos"
  }

  cloudinit_input = {
    for name, vm in local.cloudinit_vms : name => {
      os_type    = vm.os_type
      hostname   = name
      ssh_public = var.ssh_public
      networks   = vm.networks
    }
  }
}

module "cloudinit" {
  source       = "../cloudinit"
  vms          = local.cloudinit_input
  storage_pool = var.storage_pool

  depends_on = [module.volume]
}

Important: the conditional filter (if ...) is mandatory if the original map contains Windows VMs.

Outputs

• cloudinit_volumes: map indexed by VM name, containing:

  • name: ISO volume name (e.g., "SdnsDMZ01-cloudinit.iso")
  • pool: storage pool name

This output is used by the domain_linux module to attach the ISO as a configuration device.

Known Limitations

• Does not support multiple SSH keys per VM (only a single ssh_public object)
• Does not generate ISOs for VMs without a valid os_type
• Fully depends on the correctness and robustness of the provided templates
• Does not perform semantic validation of network configuration before rendering