Developer(s) | Richard Jones |
---|---|
Initial release | April 4, 2009 [1] |
Stable release | 1.40 / February 8, 2019 [2] |
Written in | C; utilities in OCaml Perl, et al. |
Operating system | Linux |
Type | Virtualization |
License | LGPL, GPL |
Website | libguestfs |
libguestfs is a C library and a set of tools for accessing and modifying virtual disk images used in platform virtualization. The tools can be used for viewing and editing virtual machines (VMs) managed by libvirt and files inside VMs, scripting changes to VMs, creating VMs, and much else besides. [3] It was created because of security issues, when virtual disk images are mounted directly on the host system. [4]
libguestfs can access nearly any type of file system including: all known types of Linux filesystem (ext2/3/4, XFS, btrfs, etc.), any Windows filesystem (VFAT and NTFS), any Mac OS X and BSD filesystems, LVM2 volume management, MBR and GPT disk partitions, raw disks, qcow2, VirtualBox VDI, VMWare VMDK, Hyper-V VHD/VHDX, on files, local devices, CD and DVD ISOs, SD cards, or remotely over FTP, HTTP, SSH, iSCSI, NBD, GlusterFS, Ceph, Sheepdog, and much more. libguestfs does not require root permissions.
The functionality is available through a shell called guestfish. There is a rescue shell called virt-rescue for fixing unbootable virtual machines. Multiple tools are available modeled after ordinary Unix commands, such as virt-cat and virt-tar. [5]
libguestfs is also an API that can be linked with C and C++ management programs and has bindings for Perl, Python, Ruby, Java, OCaml, PHP, Haskell, Erlang, Lua, Golang and C#. It can be used from shell scripts or in the command line. Using the FUSE module guest filesystems can be mounted on the host with the guestmount command. [6]
libguestfs is implemented using the Kernel-based Virtual Machine for the Linux kernel. [7]
ext3, or third extended filesystem, is a journaled file system that is commonly used by the Linux kernel. It used to be the default file system for many popular Linux distributions. Stephen Tweedie first revealed that he was working on extending ext2 in Journaling the Linux ext2fs Filesystem in a 1998 paper, and later in a February 1999 kernel mailing list posting. The filesystem was merged with the mainline Linux kernel in November 2001 from 2.4.15 onward. Its main advantage over ext2 is journaling, which improves reliability and eliminates the need to check the file system after an unclean shutdown. Its successor is ext4.
Linux has several filesystem drivers for the File Allocation Table (FAT) filesystem format. These are commonly known by the names used in the mount
command to invoke particular drivers in the kernel: msdos, vfat, and umsdos.
A live CD is a complete bootable computer installation including operating system which runs directly from a CD-ROM or similar storage device into a computer's memory, rather than loading from a hard disk drive. A live CD allows users to run an operating system for any purpose without installing it or making any changes to the computer's configuration. Live CDs can run on a computer without secondary storage, such as a hard disk drive, or with a corrupted hard disk drive or file system, allowing data recovery.
tmpfs is a temporary file storage paradigm implemented in many Unix-like operating systems. It is intended to appear as a mounted file system, but data is stored in volatile memory instead of a persistent storage device. A similar construction is a RAM disk, which appears as a virtual disk drive and hosts a disk file system.
9P is a network protocol developed for the Plan 9 from Bell Labs distributed operating system as the means of connecting the components of a Plan 9 system. Files are key objects in Plan 9. They represent windows, network connections, processes, and almost anything else available in the operating system.
Linux-VServer is a virtual private server implementation that was created by adding operating system-level virtualization capabilities to the Linux kernel. It is developed and distributed as open-source software.
QEMU is a free and open-source emulator. It emulates a computer's processor through dynamic binary translation and provides a set of different hardware and device models for the machine, enabling it to run a variety of guest operating systems. It can interoperate with Kernel-based Virtual Machine (KVM) to run virtual machines at near-native speed. QEMU can also do emulation for user-level processes, allowing applications compiled for one architecture to run on another.
In computer data storage, a volume or logical drive is a single accessible storage area with a single file system, typically resident on a single partition of a hard disk. Although a volume might be different from a physical disk drive, it can still be accessed with an operating system's logical interface. However, a volume differs from a partition.
In Linux systems, initrd
is a scheme for loading a temporary root file system into memory, to be used as part of the Linux startup process. initrd
and initramfs
refer to two different methods of achieving this. Both are commonly used to make preparations before the real root file system can be mounted.
In Unix-like operating systems, a loop device, vnd, or lofi is a pseudo-device that makes a computer file accessible as a block device.
virt-manager is a desktop virtual machine monitor primarily developed by Red Hat.
The following is a timeline of virtualization development. In computing, virtualization is the use of a computer to simulate another computer. Through virtualization, a host simulates a guest by exposing virtual hardware devices, which may be done through software or by allowing access to a physical device connected to the machine.
Kernel-based Virtual Machine (KVM) is a free and open-source virtualization module in the Linux kernel that allows the kernel to function as a hypervisor. It was merged into the mainline Linux kernel in version 2.6.20, which was released on February 5, 2007. KVM requires a processor with hardware virtualization extensions, such as Intel VT or AMD-V. KVM has also been ported to other operating systems such as FreeBSD and illumos in the form of loadable kernel modules.
Wubi is a free software Ubuntu installer, that was the official Windows-based software, from 2008 until 2013, to install Ubuntu from within Windows, to a single file within an existing Windows partition.
The Linux booting process involves multiple stages and is in many ways similar to the BSD and other Unix-style boot processes, from which it derives. Although the Linux booting process depend very much on the computer architecture, those architectures share similar stages and software components, including system startup, bootloader execution, loading and startup of a Linux kernel image, and execution of various startup scripts and daemons. Those are grouped into 4 steps: system startup, bootloader stage, kernel stage, and init process. When a Linux system is powered up or reset, its processor will execute a specific firmware/program for system initialization, such as Power-on self-test, invoking the reset vector to start a program at a known address in flash/ROM, then load the bootloader into RAM for later execution. In personal computer (PC), not only limited to Linux-distro PC, this firmware/program is called BIOS, which is stored in the mainboard. In embedded Linux system, this firmware/program is called boot ROM. After being loaded into RAM, bootloader will execute to load the second-stage bootloader. The second-stage bootloader will load the kernel image into memory, decompress and initialize it then pass control to this kernel image. Second-stage bootloader also performs several operation on the system such as system hardware check, mounting the root device, loading the necessary kernel modules,... Finally, the very first user-space process starts, and other high-level system initializations are performed.
oVirt is a free, open-source virtualization management platform. It was founded by Red Hat as a community project on which Red Hat Virtualization is based. It allows centralized management of virtual machines, compute, storage and networking resources, from an easy-to-use web-based front-end with platform independent access. KVM on x86-64, PowerPC64 and s390x architecture are the only hypervisors supported, but there is an ongoing effort to support ARM architecture in a future releases.
libvirt is an open-source API, daemon and management tool for managing platform virtualization. It can be used to manage KVM, Xen, VMware ESXi, QEMU and other virtualization technologies. These APIs are widely used in the orchestration layer of hypervisors in the development of a cloud-based solution.
QVD is an open-source virtual desktop infrastructure (VDI) product built on Linux. Its main purpose is to provide remote desktops to users.
Google Compute Engine (GCE) is the Infrastructure as a Service (IaaS) component of Google Cloud Platform which is built on the global infrastructure that runs Google's search engine, Gmail, YouTube and other services. Google Compute Engine enables users to launch virtual machines (VMs) on demand. VMs can be launched from the standard images or custom images created by users. GCE users must authenticate based on OAuth 2.0 before launching the VMs. Google Compute Engine can be accessed via the Developer Console, RESTful API or command-line interface (CLI).
bhyve is a type-2 hypervisor initially written for FreeBSD. It can also be used on a number of illumos based distributions including SmartOS, OpenIndiana, and OmniOS. A port of bhyve to macOS called xhyve is also available.