Creating a volume in a pool of type zfs requires the format to be specified

[lod]

Using 0.9

Defining a volume that sits on a ZFS pool I get an error during the apply process.

resource "libvirt_volume" "worker_node" {
  name           = "worker_node_${count.index}"
  pool           = "zfs"  # defined manually
  capacity           = 8 * 1024 * 1024 * 1024  # 8G, 4G is too small for talos
  count = 1
}

│ Error: Provider returned invalid result object after apply
│
│ After the apply operation, the provider still indicated an unknown value for
│ libvirt_volume.control_node[0].format. All values must be known after apply, so this is always a bug in
│ the provider and should be reported in the provider's own repository. OpenTofu will still save the
│ other known object values in the state.

$ virsh pool-dumpxml zfs
<pool type='zfs'>
  <name>zfs</name>
  <uuid>0e7ba73b-a220-405e-9bd1-e3659be13ee3</uuid>
  <capacity unit='bytes'>8985071583232</capacity>
  <allocation unit='bytes'>6428156966912</allocation>
  <available unit='bytes'>2556914616320</available>
  <source>
    <name>tank</name>
  </source>
  <target>
    <path>/dev/zvol/tank</path>
  </target>
</pool>

The volume is created, I can see it in vol-list.

Setting the format explicitly to qcow2 works as expected.

This is a step forward from 0.8 where there were errors during the creation process and the only workaround I found was to use a different pool.

libvirt_pool does document that it supports limited pool types, not including zfs. However a manually defined pool should be expected to be usable.