LXC

Last updated
Linux Containers
Developer(s)
  • Kernel: Virtuozzo, IBM, Google, Eric Biederman and others
  • Userspace: Daniel Lezcano, Serge Hallyn, Stéphane Graber and others
Initial releaseAugust 6, 2008;15 years ago (2008-08-06) [1]
Stable release
5.0.3 [2]   OOjs UI icon edit-ltr-progressive.svg / 25 July 2023;8 months ago (25 July 2023)
Repository
Written in C, Shell
Operating system Linux
Platform x86, IA-64, PowerPC, SPARC, Itanium, ARM
Type OS-level virtualization
License GNU LGPL v.2.1 (some components under GNU GPL v2 and BSD)
Website linuxcontainers.org

Linux Containers (LXC) is an operating-system-level virtualization method for running multiple isolated Linux systems (containers) on a control host using a single Linux kernel.

Contents

The Linux kernel provides the cgroups functionality that allows limitation and prioritization of resources (CPU, memory, block I/O, network, etc.) without the need for starting any virtual machines, and also the namespace isolation functionality that allows complete isolation of an application's view of the operating environment, including process trees, networking, user IDs and mounted file systems. [3]

LXC combines the kernel's cgroups and support for isolated namespaces to provide an isolated environment for applications. [4] Early versions of Docker used LXC as the container execution driver, [4] though LXC was made optional in v0.9 and support was dropped in Docker v1.10. [5] [6]

Overview

LXC was initially developed by IBM, as part of a collaboration between several parties looking to add namespaces to the kernel. [7] It provides operating system-level virtualization through a virtual environment that has its own process and network space, instead of creating a full-fledged virtual machine. LXC relies on the Linux kernel cgroups functionality [8] that was released in version 2.6.24. It also relies on other kinds of namespace isolation functionality, which were developed and integrated into the mainline Linux kernel.

Security

Originally, LXC containers were not as secure as other OS-level virtualization methods such as OpenVZ: in Linux kernels before 3.8, the root user of the guest system could run arbitrary code on the host system with root privileges, just as they can in chroot jails. [9] Starting with the LXC 1.0 release, it is possible to run containers as regular users on the host using "unprivileged containers". [10] Unprivileged containers are more limited in that they cannot access hardware directly. However, even privileged containers should provide adequate isolation in the LXC 1.0 security model, if properly configured. [10]

Alternatives

LXC is similar to other OS-level virtualization technologies on Linux such as OpenVZ and Linux-VServer, as well as those on other operating systems such as FreeBSD jails, AIX Workload Partitions and Solaris Containers. In contrast to OpenVZ, LXC works in the vanilla Linux kernel requiring no additional patches to be applied to the kernel sources. Version 1 of LXC, which was released on 20 February 2014 as a long-term supported version, was supported for five years. [11] LXC 4.0 will be supported until June 1, 2025 and LXC 5.0 until June 1, 2027. [12]

LXD

LXD is an alternative Linux container manager, written in Go. It is built on top of LXC and aims to provide a better user experience. [13] It is a container hypervisor providing an API to manage LXC containers. [14] The LXD project was started in 2015 and was sponsored from the start by Canonical Ltd., the company behind Ubuntu Linux. On 4 July 2023, the LinuxContainers project announced that Canonical had decided to take over the LXD project but a fork called Incus was made. [15] [16] On August 25, 2023, LXD version 5.17 was officially released under the control of Canonical, providing support for OpenZFS 2.2 delegation capabilities. [17]

See also

Related Research Articles

chroot is an operation on Unix and Unix-like operating systems that changes the apparent root directory for the current running process and its children. A program that is run in such a modified environment cannot name files outside the designated directory tree. The term "chroot" may refer to the chroot(2) system call or the chroot(8) wrapper program. The modified environment is called a chroot jail.

<span class="mw-page-title-main">Cooperative Linux</span> Software to run both Windows and Linux

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OS-level virtualization is an operating system (OS) virtualization paradigm in which the kernel allows the existence of multiple isolated user space instances, called containers, zones, virtual private servers (OpenVZ), partitions, virtual environments (VEs), virtual kernels, or jails. Such instances may look like real computers from the point of view of programs running in them. A computer program running on an ordinary operating system can see all resources of that computer. However, programs running inside of a container can only see the container's contents and devices assigned to the container.

<span class="mw-page-title-main">OpenVZ</span> Operating-system level virtualization technology

OpenVZ is an operating-system-level virtualization technology for Linux. It allows a physical server to run multiple isolated operating system instances, called containers, virtual private servers (VPSs), or virtual environments (VEs). OpenVZ is similar to Solaris Containers and LXC.

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<span class="mw-page-title-main">TurnKey Linux Virtual Appliance Library</span> Open-Source virtual appliance library

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libvirt Management tool

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lmctfy is an implementation of an operating system–level virtualization, which is based on the Linux kernel's cgroups functionality.

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References

  1. ↑ "Downloads". Linux containers. Archived from the original on 2014-11-10. Retrieved 2014-11-10.
  2. ↑ "Release 5.0.3". 25 July 2023. Retrieved 26 July 2023.
  3. ↑ Rami Rosen (May 2013). "Resource management: Linux kernel namespaces and cgroups" (PDF). CS. UCSB. Retrieved February 11, 2015.
  4. 1 2 Kenlon, Seth (2020-01-30). "Exploring simple Linux containers with lxc". Red Hat . IBM. Retrieved 2023-07-05.
  5. ↑ "Docker 0.9: introducing execution drivers and libcontainer". Blog. Docker. 2014-03-10. Retrieved 2018-05-09.
  6. ↑ "1.10.0". Engine release notes. Docker. 2016-02-04. Retrieved 2020-10-06.
  7. ↑ Webb, Jordan (2022-09-13). "LXC and LXD: a different container story". LWN.net . Retrieved 2023-07-05.
  8. ↑ Koutoupis, Petros (2018-08-27). "Everything You Need to Know about Linux Containers, Part II: Working with Linux Containers (LXC)". Linux Journal . Retrieved 2023-07-05.
  9. ↑ Marco, d'Itri (2011). "Evading from linux containers". BOFH. IT. Archived from the original on 9 January 2014. Retrieved 12 February 2014.
  10. 1 2 Graber, Stéphane (1 January 2014). "LXC 1.0: Security features [6/10]" . Retrieved 12 February 2014. However, at least in Ubuntu, our default containers ship with what we think is a pretty good configuration of both the cgroup access and an extensive apparmor profile which prevents all attacks that we are aware of. [...] LXC is no longer running as root so even if an attacker manages to escape the container, he'd find himself having the privileges of a regular user on the host
  11. ↑ Graber, Stéphane (2013-12-20). "LXC 1.0: Your first Ubuntu container". St. Graber. Retrieved 2014-02-23.
  12. ↑ "LXC". Linux containers. Retrieved 2023-02-07.
  13. ↑ "Introdution". LXD. Linux Containers. Retrieved 2020-04-14.
  14. ↑ Parrott, Thomas. "Introduction to LXD projects". Ubuntu. Canonical. Retrieved 2023-07-05.
  15. ↑ "LXD Has been moved to Canonical". Linux Containers. 2023-07-04. Archived from the original on 2023-07-04. Retrieved 2023-07-05.
  16. ↑ Rudra, Sourav (2023-07-05). "The LXD Project Finds a New Home at Canonical". It’s Foss. Retrieved 2023-07-05.
  17. ↑ Parrott, Thomas (25 August 2023). "LXD 5.17 has been released". Ubuntu. Canonical.
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