Introduction to Linux Containerization
Containerization, at its core, is a technology that empowers the isolation of processes, allowing applications and services to run independently from one another. It involves executing your applications within isolated environments known as containers, each originating from a distinct image containing all the necessary files to support the processes.
Essentially, Linux containers leverage OS-level virtualization, enabling the execution of multiple isolated Linux systems (containers) on a control host utilizing a single Linux kernel.
How Linux Kernel Isolates Containers?
The Linux kernel achieves container isolation through the functionalities of cgroups and namespace isolation. Control Groups (cgroups) is a Linux kernel feature that isolates processes by allocating predefined resources such as CPU, memory, disk I/O, and network.
Namespaces organize various objects, facilitating the complete isolation of an application’s view of the operating environment, including process trees, networking, user IDs, and mounted file systems.
Why containers?
Containers significantly expedite the application deployment process due to their platform independence. Imagine running an application on a live production server and needing to deploy changes periodically. Containerization simplifies this process by reducing the time required for rewriting, debugging, and fixing bugs on your app.
Containers offer the flexibility to execute the same application on your local machine for testing. Once validated, deployment on the production environment becomes a seamless process, regardless of the underlying infrastructure.
Different from Traditional Virtualization
While Linux virtualization involves running multiple operating systems concurrently, containerization isolates applications by sharing the same operating system kernel. Unlike traditional virtual machines, containers are lightweight and more portable.
The concept of Linux containers drew inspiration from FreeBSD jail, a technology that partitions a FreeBSD system into multiple subsystems. Containers evolved through the integration of technologies like cgroups, namespace, systemd, etc.
Containerization Techniques
Several containerization techniques exist, including LXC, systemd-nspawn, and Docker. Docker, in particular, has gained immense popularity in the industry, combining the strengths of LXC with enhanced tools for developers, enhancing container usability.
In essence, Linux containerization revolutionizes application development, deployment, and management. Container images provide portability and version control, ensuring that applications work consistently across different environments. The lightweight, portable, and platform-independent nature of Linux containers makes them a powerful tool in modern software development.
You are running an application on a live production server and you need to deploy changes on your application periodically. The containerization technique helps the deployment process painlessly by reducing the total time required for rewriting, and break/bug-fixing on your App.