Written in C, Python, Shell, Lua | Operating system | |
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Developer(s) Kernel: Virtuozzo, IBM, Google, Eric Biederman and others
Userspace: Daniel Lezcano, Serge Hallyn, Stéphane Graber and others Initial release August 6, 2008; 8 years ago (2008-08-06) Stable release 2.0.6 / 23 November 2016; 3 months ago (2016-11-23) Platform x86, IA-64, PowerPC, SPARC, Itanium, ARM | ||
LXC (Linux Containers) 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 namespace isolation functionality that allows complete isolation of an applications' view of the operating environment, including process trees, networking, user IDs and mounted file systems.
LXC combines the kernel's cgroups and support for isolated namespaces to provide an isolated environment for applications. Docker can also use LXC as one of its execution drivers, enabling image management and providing deployment services.
Overview
LXC 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 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, much like chroot jails. Starting with the LXC 1.0 release, it is possible to run containers as regular users on the host using "unprivileged containers". Unprivileged containers are more limited in that they cannot access hardware directly. Nevertheless, even privileged containers should provide adequate isolation in the LXC 1.0 security model, if properly configured.
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, is a long-term supported version and intended to be supported for five years.