fix(lxc): allow container disk size 0 for lxc zfs/brfs subvols

[h3krn]

Contributor's Note

The proxmox pct command allows for disk size = 0 to create containers backed by ZFS or BTRFS subvolumes. (Note that this is still not allowed by the GUI.) This would allow the provider to use this feature as well.

https://pve.proxmox.com/pve-docs/pct.1.html

Storage Backed Mount Points

    Directories: passing size=0 triggers a special case where instead of a raw image a directory is created.

• I have added / updated documentation in /docs for any user-facing features or additions.
• I have added / updated acceptance tests in /fwprovider/tests for any new or updated resources / data sources.
• I have ran make example to verify that the change works as expected.

Proof of Work

# tofu show
# proxmox_virtual_environment_container.k3s-controller[0]:
resource "proxmox_virtual_environment_container" "k3s-controller" {
    id             = "134"
    node_name      = "pve-host"
    protection     = false
    start_on_boot  = true
    started        = true
    tags           = [
        "k3s-controller",
    ]
    template       = false
    timeout_clone  = 1800
    timeout_create = 1800
    timeout_delete = 60
    timeout_start  = 300
    timeout_update = 1800
    unprivileged   = false
    vm_id          = 134

    cpu {
        architecture = "amd64"
        cores        = 2
        units        = 1024
    }

    disk {
        datastore_id = "local-btrfs"
        size         = 0
    }

    features {
        fuse    = false
        keyctl  = false
        mount   = []
        nesting = true
    }

    initialization {
        hostname = "k3s-controller-01"

        ip_config {
            ipv4 {
                address = "dhcp"
            }
        }

        user_account {
            keys = [
                "<SNIP>",
            ]
        }
    }

    memory {
        dedicated = 4096
        swap      = 0
    }

    network_interface {
        bridge      = "vmbr0"
        enabled     = true
        firewall    = false
        mac_address = "BC:24:11:93:9B:B9"
        mtu         = 0
        name        = "eth0"
        rate_limit  = 0
        vlan_id     = 0
    }

    operating_system {
        template_file_id = "local-btrfs:vztmpl/debian-12-standard_12.7-1_amd64.tar.zst"
        type             = "debian"
    }
}

pve-host:~# btrfs subvolume list / | grep 134
ID 13885 gen 4345930 top level 256 path var/lib/pve/local-btrfs/images/134/subvol-134-disk-0.subvol

Community Note

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Closes #0000 | Relates #0000

[bpg]

Thanks for the fix @h3krn!

LGTM! 🚀

[bpg]

@all-contributors please add @h3krn for code

[allcontributors]

@bpg

I've put up a pull request to add @h3krn! 🎉