F OpenNebula/one#7370: Refactor model disk detection in vllm engine

    # ------------------------------------------------------------------------------

    def detect_and_mount_model_disk

        # Auto-detect model disk (first non-OS disk)

        os_disk = detect_os_disk

        # Find additional disks (both block devices and virtiofs)

        # Find additional disks (both block devices and virtiofs) except the OS and context disks

        additional_disks = find_additional_disks(os_disk)

        if additional_disks.empty?

            return nil

        end

        # Probe candidates: mount, check HF signature, keep only the matching disk mounted

        # Mount the first candidate disk and return its path for vLLM

        additional_disks.each do |model_disk|

            mount_path = determine_default_mount_path(model_disk)

            disk_format = detect_disk_format(model_disk)

            already_mounted = mountpoint?(mount_path)

            msg :info, "Probing model disk: #{model_disk} (format: #{disk_format}), mount #{mount_path}"

            msg :info, "Mounting model disk: #{model_disk} (format: #{disk_format}), mount #{mount_path}"

            mounted_path = mount_disk_by_format(model_disk, mount_path, disk_format)

            next unless mounted_path

            if model_disk_signature?(mounted_path)

                msg :info, "Selected model disk: #{model_disk}"

                return mounted_path

            end

            msg :warn, "Disk #{model_disk} missing HF signature, skipping"

            # Unmount test mounts so only the selected model disk stays mounted

            Open3.capture3("umount #{mounted_path} 2>/dev/null") unless already_mounted

            return mounted_path if mounted_path

        end

        msg :error, "No model disk detected. vllm-engine requires a model disk to be attached."

        'vda'  # Default fallback

    end

    # True if path is already a mountpoint (avoid unmounting user mounts)

    def mountpoint?(path)

        _stdout, _stderr, status = Open3.capture3("mountpoint -q #{path}")

        status.success?

    end/opt/one-ee/src/mad/sh/create_hf_image.sh

    # Heuristic to detect HuggingFace model disks by file signature.

    def model_disk_signature?(mount_path)

        #TODO: We could improve this by injecting a marker file in the model disk when the model image is created (in /one-ee/src/mad/sh/create_hf_image.sh)

        config = File.exist?(File.join(mount_path, 'config.json'))

        tokenizer = File.exist?(File.join(mount_path, 'tokenizer.json')) ||

                    File.exist?(File.join(mount_path, 'tokenizer_config.json'))

        # Quick top-level weight file check (no recursive scan on large disks)

        weights = false

        Dir.each_child(mount_path) do |entry|

            if entry == 'pytorch_model.bin' ||

               entry.end_with?('.safetensors') ||

               entry.end_with?('.gguf')

                weights = true

                break

            end

        end

        msg :info, "Model signature check at #{mount_path}: config=#{config}, tokenizer=#{tokenizer}, weights=#{weights}"

        config && tokenizer && weights

    end

    # Return non-OS disks and virtiofs tags, excluding the OS and context disks

    def find_additional_disks(os_disk)

        disks = []

        # Find block devices (qcow2 format)