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Container technology is everywhere and constantly evolving, so it behooves IT architects, engineers and administrators to keep track of container standards organizations and projects.
While there are many versions of commercial container products, the bulk of the field grows in open source communities. Organizations that create and manage virtual container standards overlap, while working together to provide IT operations with all the necessary tools and resources to implement and maintain containers.
This simple glossary covers the basics of what you need to know to keep up in the conversation about containers in production.
Containerization: Containerization is a virtualization method that exists on the OS level, rather than at the hardware level where traditional server virtualization occurs. Because containers are isolated environments that share a single OS kernel, they can move across hosts and platforms more easily than virtual machines.
Open Container Initiative: The Linux Foundation designed the OCI to establish common standards for container virtualization technologies. Introduced as Open Containers Project at DockerCon in 2015, the OCI has remained independent of any commercial organization. www.opencontainers.org
Linux Containers Project: This project, which is built and designed as a distributor- and vendor-neutral environment, aims to develop Linux containers. LCP's primary focus is system containers; it uses kernel features such as namespaces, mandatory access control and control groups to secure containers. The LCP's three active projects are LXC, LXD and LXCFS. www.linuxcontainers.org
LXC (Linux Containers): LXC is an OS-level virtualization environment for system management and application containers. LXC strikes a middle ground between a chroot -- a Unix system call that remaps an application's directory and restricts program access to files in a given directory and its children -- and a full VM. The goal is to use a single kernel and create a nearly identical environment to a standard Linux installation. www.linuxcontainers.org/lxc/introduction
LXD (Linux container hypervisor): LXD is a Canonical-founded and Apache 2 licensed open source project that acts as a set of tools for container deployment, management and security. LXD acts much like a pure hypervisor, abstracting the physical and virtual layers of the stack, while providing the speed and density benefits of a container. www.linuxcontainers.org/lxd/introduction
LXCFS: This simple userspace filesystem is designed to work around some of the limitations of Linux kernels, such as floating stack size limits and the overall need to ensure that modules compiled into the build are all compatible. The LXCFS 2.0 update includes a cgroup namespace in the Linux kernel, which eliminates the need for systemd-based containers. The focus, instead, is to make containers act like independent systems through a proc-masking feature. www.linuxcontainers.org/lxcfs/introduction
Docker: This open source program enables developers to package Linux applications and their dependencies as containers. Docker technology standardizes application program delivery, which allows apps to run in any physical or virtual Linux environment. www.docker.io
APPC: Advanced Program-to-Program Communication, or LU 6.2, is an open standard communication protocol and programming interface standard supported on most platforms. APPC enables high-speed communications between programs that reside on different computers, and between workstation, midrange systems and mainframe servers. APPC and OCI have some overlap in the realm of virtual container standards, but OCI focuses on runtime while APPC's main focus is on container image and image distribution. This allows users to build a single container and run it in different container software without rebuilding.
Open Systems Interconnection: The OSI reference model illustrates how applications communicate across a network. Its purpose is to guide vendors and developers toward making digital communication products and software programs interoperable. OSI was originally intended as a detailed specification of actual interfaces, but was reformatted into a common reference model standard. Eventually, the ISO adopted it. www.iso.org
CNCF: The Cloud Native Computing Foundation is a nonprofit organization hosted by The Linux Foundation. CNCF aims to create new common container technologies inspired by internet-scale computing to advance the development of cloud-native technologies and services. www.cncf.io
Nothing stands still in the world of container virtualization. If you would like to see another container project added to this list, email us.
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