Creating a VM with cloud-init and disk passthrough

[Dageus]

I tried almost everything but couldn't reach an answer so I'm here.
I wanted to create a Debian VM using terraform that was configured using cloud-init. But I wanted the main disk to be an external NVMe that I have connected via usb to my host so the VM could fully manage it.

I reached this partial solution:

resource "proxmox_virtual_environment_download_file" "debian_cloud_image" {
  node_name    = "pve"
  datastore_id = "local"
  content_type = "import"
  url          = "https://cloud.debian.org/images/cloud/bookworm/latest/debian-12-genericcloud-amd64.qcow2"
}

resource "proxmox_virtual_environment_vm" "openmediavault" {
  node_name       = "pve"
  name            = "openmediavault"
  vm_id           = 201
  started         = false
  on_boot         = false
  stop_on_destroy = true

  tags = ["nas", "terraform_provisioned"]

  agent {
    enabled = true
  }

  startup {
    order      = "2"
    up_delay   = "60"
    down_delay = "60"
  }

  # CPU / Memory
  cpu {
    cores   = 2
    sockets = 1
    type    = "host"
    flags   = ["-aes"] # my host's CPU doesn't support AES
  }

  memory {
    dedicated = 2048
    floating  = 2048
  }

  scsi_hardware = "virtio-scsi-single"

  bios = "ovmf"
  efi_disk {
    datastore_id = "local"
  }

  # Main system disk from Debian cloud image
  disk {
    datastore_id = "local"
    import_from  = proxmox_virtual_environment_download_file.debian_cloud_image.id
    interface    = "virtio0"
    iothread     = true
    discard      = "on"
    size         = 20
  }

  # NOTE:
  # External SSD passthrough
  # will be done via Ansible/Null Resource

  # Network
  network_device {
    model  = "virtio"
    bridge = "vmbr0"
  }


  # Cloud-init / SSH / networking
  initialization {
    datastore_id = "local"
    user_account {
      username = "root"
      keys     = [file("~/.ssh/ansible_ssh.pub")]
      password = "root"
    }

    ip_config {
      ipv4 {
        address = "192.168.1.212/24"
        gateway = "192.168.1.1"
      }
    }
  }

  # Boot order
  boot_order = ["scsi0"]

  lifecycle {
    ignore_changes = [disk]
  }
}

resource "null_resource" "configure_and_start" {
  depends_on = [proxmox_virtual_environment_vm.openmediavault]

  provisioner "local-exec" {
    command = <<-EOT
    ansible-playbook \
      -i ../ansible/inventories/inventory.ini \
      -e "vmid=${proxmox_virtual_environment_vm.openmediavault.vm_id}" \
      -e "disk_id=${var.external_ssd_disk_name}" \
      -e "vm_ssh_ip=192.168.1.212" \
      ../ansible/playbooks/attach_disk_and_start_vm.yml
  EOT
  }

  triggers = {
    vm_id = proxmox_virtual_environment_vm.openmediavault.vm_id
  }
}

and I had this playbook to attach the external SSD:

---
- name: Attach disk and start VM (idempotent)
  hosts: proxmox
  become: yes
  gather_facts: no
  serial: 1

  vars:
    vmid: "{{ vmid | int }}"
    disk_id: "{{ disk_id }}"
    max_sata_slots: 5
    vm_ssh_ip: "{{ vm_ssh_ip | default('192.168.1.212') }}"
    ssh_wait_timeout: 300

  tasks:
    - name: Verify disk exists on host
      ansible.builtin.stat:
        path: "/dev/disk/by-id/{{ disk_id }}"
      register: disk_check
      failed_when: not disk_check.stat.exists
      changed_when: false

    - name: Get current VM configuration
      ansible.builtin.command: qm config {{ vmid }}
      register: vm_config
      changed_when: false
      failed_when: vm_config.rc != 0
      retries: 3
      delay: 2
      until: vm_config.rc == 0

    - name: Get VM status
      ansible.builtin.command: qm status {{ vmid }}
      register: vm_status
      changed_when: false
      failed_when: false

    - name: Attempt graceful shutdown if VM is running
      ansible.builtin.command: qm shutdown {{ vmid }}
      register: shutdown_result
      when: "'running' in vm_status.stdout or 'status: running' in vm_status.stdout"
      failed_when: false

    - name: wait for vm to stop
      ansible.builtin.command: qm status {{ vmid }}
      register: status_check_grace
      retries: 10
      delay: 4
      until: "'stopped' in status_check_grace.stdout or 'status: stopped' in status_check_grace.stdout"
      when: shutdown_result is defined and shutdown_result.get('rc', 0) == 0
      failed_when: false

    - name: Force stop VM if still running after graceful attempt
      ansible.builtin.command: qm stop {{ vmid }}
      register: force_stop_result
      when:
        - "'running' in status_check_grace.stdout"
        - "'status: running' in status_check_grace.stdout"
        - "'running' in vm_status.stdout and (shutdown_result is not defined or shutdown_result.rc != 0)"
      failed_when: force_stop_result.rc != 0
      changed_when: force_stop_result.rc == 0

    - name: Attach the disk
      ansible.builtin.command: qm set {{ vmid }} -sata0 /dev/disk/by-id/{{ disk_id }}
      register: attach_result
      changed_when: attach_result.rc == 0
      failed_when: attach_result.rc != 0

    - name: Re-read VM config after attach
      ansible.builtin.command: qm config {{ vmid }}
      register: vm_config_after
      changed_when: false
      failed_when: vm_config_after.rc != 0

    - name: Assert disk is present in VM config
      ansible.builtin.assert:
        that:
          - "'/dev/disk/by-id/{{ disk_id }}' in vm_config_after.stdout"
        fail_msg: "Disk attachment failed; /dev/disk/by-id/{{ disk_id }} not found in VM config."

    - name: Start VM (if not running)
      ansible.builtin.command: qm start {{ vmid }}
      register: start_result
      when: >
        not (
          "running" in vm_config_after.stdout
          or "status: running" in vm_config_after.stdout
        )
      failed_when: start_result.rc != 0
      changed_when: start_result.rc == 0

    - name: Wait for VM to become running
      ansible.builtin.command: qm status {{ vmid }}
      register: final_status
      retries: 12
      delay: 5
      until: "'running' in final_status.stdout or 'status: running' in final_status.stdout"

    - name: Final message
      ansible.builtin.debug:
        msg: "VM {{ vmid }} started and /dev/disk/by-id/{{ disk_id }} attached at sata{{ target_sata_slot | default('already-attached') }}"

but when I go to the proxmox WebUI I have an error saying:

TASK ERROR: command '/usr/bin/qemu-img resize -f qcow2 /var/lib/vz/images/201/vm-201-disk-0.qcow2 21474836480' failed: got timeout

this is the output after the scripts run:

and when I go to the console of the VM I get this screen:

Has anybody ever attempted this or has a solution?

Thank you so much

[Dageus]

Additionally, when I try to follow the guide for disk passthrough on the proxmox registry, I get this error:

│ Error: Missing required argument
│ 
│   on openmediavault.tf line 51, in resource "proxmox_virtual_environment_vm" "openmediavault":
│   51:   disk {
│ 
│ The argument "interface" is required, but no definition was found.
╵

[Dageus]

This is the output of qemu-img info on the qcow2 disk:

root@pve:~# qemu-img info /var/lib/vz/images/201/vm-201-disk-1.qcow2 
image: /var/lib/vz/images/201/vm-201-disk-1.qcow2
file format: qcow2
virtual size: 20 GiB (21474836480 bytes)
disk size: 1.01 GiB
cluster_size: 65536
Format specific information:
    compat: 1.1
    compression type: zlib
    lazy refcounts: false
    refcount bits: 16
    corrupt: false
    extended l2: false
Child node '/file':
    filename: /var/lib/vz/images/201/vm-201-disk-1.qcow2
    protocol type: file
    file length: 3 GiB (3221946368 bytes)
    disk size: 1.01 GiB

[Dageus]

The issue was not defining a serial port in the resource.
I'll close the this discussion now.