$ show libguestfs/virt-v2v
virt-v2v is a production-grade virtual machine conversion tool that converts guests from foreign hypervisors (VMware vSphere/ESXi, Xen, Hyper-V, OVA, disk images) to run on KVM/libvirt. It supports multiple input sources (local disk, libvirt-managed guests, OVA archives, VMware VMX, vCenter HTTPS, VDDK, NFC, Xen over SSH) and output targets (local disk, libvirt, QEMU, oVirt/RHV, OpenStack, KubeVirt, VDSM, Glance, null). The conversion process inspects the guest OS (Linux, Windows) using libguestfs, injects virtio drivers for Windows, adjusts boot configuration, remaps block devices and network interfaces, and generates appropriate metadata (OVF, libvirt XML, KubeVirt YAML). It uses nbdkit as a universal disk access layer, enabling parallel copy via nbdcopy and efficient sparse allocation. The codebase is written primarily in OCaml with C stubs and embedded Python scripts for oVirt API interactions. It features a modular architecture with well-defined input/output module signatures, shared library components (NBD_URI, nbdkit wrapper, OVF generation, YAML emitter), and an extensive test suite covering real and phony guest conversions. The project is part of the libguestfs ecosystem and is actively maintained with recent commits, CI/CD via GitHub Actions, and internationalization support.
The LLM identified 4 files worth highlighting for reuse:
Hand-rolled YAML emitter that outputs valid YAML from OCaml data structures. Uses only standard library (Buffer, String, List). Demonstrates careful handling of indentation, quoting, and multi-line strings. Could be extracted for any OCaml project needing YAML serialization without external dependencies.
Defines a simple, self-contained type for NBD URIs (Unix socket + export name) with a constructor and accessor functions. Encapsulates the pattern of referencing NBD endpoints, used throughout the codebase for disk access. Reusable in any OCaml project using the NBD protocol.
Wraps Python scripts as OCaml strings and executes them with arguments via temporary files. Handles script extraction, argument passing, and cleanup. Demonstrates a clean pattern for embedding and running external scripts in OCaml without runtime dependencies. Reusable for integrating Python scripts into OCaml applications.
Provides a helper function that forks a subprocess and changes its effective UID before executing a command. Useful for writing files with specific ownership (e.g., libvirt's qemu user). Self-contained, uses Unix module only. Reusable in any OCaml tool that needs to drop privileges for a child process.