Implement complete support for disks

[davispuh]

Currently it's not possible to configure libvirt disks like adding multiple cdrom's or NVMe's.
This PR implements complete support for disks so all disk configurations that are supported by libvirt can be achieved.

[Copilot]

Pull request overview

This PR extends fog-libvirt’s Server disk handling to support a wider range of libvirt disk configurations (multiple disks, CD-ROMs, NVMe/network-backed sources, and richer disk XML), by introducing a structured Disk model hierarchy, updating domain listing to parse disks, and adding test coverage.

Changes:

• Added a full set of Server::Disk (and nested) models to parse/build libvirt disk XML with many optional sub-elements.
• Updated domain listing to parse disks from domain XML and expose them on server attributes.
• Refactored server XML generation to emit disks from explicit :disks plus derived volume/ISO disks, and added comprehensive disk minitests.

Reviewed changes

Copilot reviewed 25 out of 25 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
minitests/server/disks_test.rb	Adds end-to-end coverage for disk JSON/XML roundtrips, mirrors, block disks, and Ceph disk XML.
lib/fog/libvirt/requests/compute/list_domains.rb	Parses <devices><disk> elements into disk attribute hashes for server listings.
lib/fog/libvirt/models/compute/util/util.rb	Adds XML attribute/value helpers and assignment casting helpers used by new models.
lib/fog/libvirt/models/compute/server/seclabel.rb	Implements a Seclabel model for disk/source security labels.
lib/fog/libvirt/models/compute/server/encryption.rb	Implements an Encryption model for disk/source encryption XML.
lib/fog/libvirt/models/compute/server/driver/virtio.rb	Adds Virtio driver feature attributes (iommu/ats/packed/page_per_vq).
lib/fog/libvirt/models/compute/server/driver/statistics.rb	Adds Driver statistics model with intervals and latency histograms.
lib/fog/libvirt/models/compute/server/driver/latency_histogram.rb	Adds latency histogram model for driver statistics XML.
lib/fog/libvirt/models/compute/server/driver/iothread.rb	Adds IOThread model for driver iothreads XML.
lib/fog/libvirt/models/compute/server/disk/target.rb	Adds Disk::Target model for target device/bus/tray/etc.
lib/fog/libvirt/models/compute/server/disk/source/reservations.rb	Adds Source reservations model for reservation XML.
lib/fog/libvirt/models/compute/server/disk/source/data_store.rb	Adds Source DataStore support (network datastore XML).
lib/fog/libvirt/models/compute/server/disk/source.rb	Adds Disk::Source model with many libvirt source options and nested elements.
lib/fog/libvirt/models/compute/server/disk/mirror.rb	Adds Disk::Mirror parsing model for mirror XML.
lib/fog/libvirt/models/compute/server/disk/metadata_cache.rb	Adds MetadataCache model used by format/driver.
lib/fog/libvirt/models/compute/server/disk/format.rb	Adds Disk::Format model (type + metadata cache).
lib/fog/libvirt/models/compute/server/disk/driver.rb	Adds Disk::Driver model with virtio fields, statistics, iothreads, metadata cache.
lib/fog/libvirt/models/compute/server/disk/backing_store.rb	Adds BackingStore model with nested backing stores, format, and source.
lib/fog/libvirt/models/compute/server/disk.rb	Adds the top-level Disk model with parse/build logic and nested components.
lib/fog/libvirt/models/compute/server.rb	Switches domain XML disk emission to new disk models and adds derived volume/ISO disk handling.
lib/fog/libvirt/models/compute/common/pci_address.rb	Adds PCI address subtype for Address.
lib/fog/libvirt/models/compute/common/drive_address.rb	Adds Drive address subtype for Address.
lib/fog/libvirt/models/compute/common/clonable_model.rb	Adds deep-clone/deep-dup support for attribute-backed models.
lib/fog/libvirt/models/compute/common/attribute_model.rb	Introduces a Fog::Model subclass tailored to attribute-only models (no service identity assumptions).
lib/fog/libvirt/models/compute/common/address.rb	Adds Address base class with subtype dispatch and XML parsing/building.

Suppressed comments (3)

lib/fog/libvirt/models/compute/server.rb:511

• volume_disks calls disks.any?, which raises when disks is nil. Since callers can create servers without :disks, this should be nil-safe (e.g., by using disks.to_a).

        def volume_disks
          used_names = disk_device_names
          @volumes.to_a.filter_map do |volume|
            next if disks.any? { |disk| disk_source_path(disk) == volume.path }

lib/fog/libvirt/models/compute/server.rb:565

• iso_disk checks disks.any?, which raises when disks is nil. Use disks.to_a.any? to handle servers created without :disks.

          return nil if disks.any? { |disk| disk_source_path(disk) == source }

lib/fog/libvirt/models/compute/server.rb:580

• disk_device_names assumes disks is always an Array, but it can be nil. This will raise when building volume/ISO disks for servers created without :disks.

        def disk_device_names
          disks.filter_map do |disk|
            target = model_cast(disk, Disk).target
            target&.dev
          end

---

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[davispuh]

Use this functionality like:

server = compute.servers.create(
  disks: [
    {
      type:   :file,
      device: :cdrom,
      source: { file: iso_path },
      target: { dev: :sda, bus: :scsi }
    },
    {
      type:   :nvme,
      device: :disk,
      source: {
        type: :pci,
        managed: true,
        namespace: 1,
        address: { bus: '0x30', slot: '0x00' }
      },
      target: { dev: :nvme0n1, bus: :virtio }
    }
  ]
)