lxc

LXC, short for Linux Containers, is a userspace interface for the Linux kernel’s containment features. It provides OS-level virtualization, allowing multiple isolated Linux systems or containers to run on a single host kernel. Containers share the host’s kernel but behave like separate, lightweight environments, making them faster to start and more resource-efficient than traditional virtual machines.

The isolation in LXC is achieved primarily through Linux namespaces, which segregate process IDs, mount points, user IDs, networks, IPC, and host names, and through control groups (cgroups) that limit and account for resource usage such as CPU, memory, and I/O. Security enhancements may include AppArmor or SELinux profiles and seccomp filtering. Unprivileged containers are possible using user namespaces, reducing the risk of host compromise.

LXC provides a suite of command-line tools and libraries, including lxc-create, lxc-start, lxc-stop, lxc-destroy, lxc-attach, lxc-ls, and lxc-info. Containers are created from templates that install a chosen Linux distribution or environment, and their configurations are defined in text files. Additional components such as LXCFS offer a virtualized view of host files for containers.

In the ecosystem, LXD is a higher-level daemon and API that manages LXC containers, providing image storage, clustering, and simplified administration. LXC serves as a lower-level container toolkit, while LXD aims to deliver a more user-friendly experience for managing system containers at scale.

History and usage notes: LXC is one of the early Linux container technologies that helped popularize OS-level virtualization. It is commonly used for development, testing, and lightweight deployment scenarios where sharing the host kernel and rapid startup are advantageous.