In the world of software engineering, the phrase “It works on my machine” is common among developers. However, sometimes, the computing environment created to run an application is not the same as the one in which it was tested or developed, leading to unexpected delays in the release cycle.

To prevent this, containers are taking the digital engineering world by storm, allowing developers to easily package their applications and dependencies into portable, isolated environments that work seamlessly across different systems.

What are containers?

At their core, containers are lightweight, portable environments that allow developers to package up an application and its dependencies into a single, self-contained and deployable unit. This means that the application can be easily moved between different computing environments, from a developer’s laptop to a production server, without any compatibility issues.

Why Containers Matter for Digital Engineering

Containers offer a range of benefits for digital engineering that have made them an essential tool for modern software development. Let’s take a closer look at some of the key advantages:

  • Minimal Overhead: Containers are designed to be as lightweight as possible, meaning they require minimal resources to run. This makes them ideal for running multiple applications on the same server without causing performance issues.
  • Portability: Containers can be easily moved between different computing environments, from a developer’s laptop to a production server, without any compatibility issues. This makes it much easier to deploy applications across different cloud providers or on-premise environments.
  • Consistent Operations: Containers ensure that applications run consistently across different environments, which is critical for avoiding unexpected behavior or errors.
  • Greater Efficiencies: Containers can be created and destroyed in seconds, allowing developers to rapidly test and deploy new features. This means that development cycles can be shortened, enabling teams to be more productive.
  • Complementing DevOps Processes: Containers work seamlessly with DevOps tools, allowing developers to automate the deployment process and integrate testing and monitoring into their workflow.
  • Compatible with Cloud Agnostic Architectures: Containers are compatible with cloud agnostic architectures, meaning that they can be easily deployed across different cloud providers without requiring any changes to the application.
  • Fault Isolation: Containers are designed to be isolated from each other, meaning that if one container fails, it won’t impact the others. This makes it easier to diagnose and fix problems.
  • Security: Containers provide an additional layer of security, by isolating the application and its dependencies from the host system. This means that if the application is compromised, it won’t affect the host system.

From Virtual Machines to Containers: A Brief History of containerisation

To understand how containers work, it’s important to explore the major milestones in the history of virtualization and containerisation. The concept of containerisation dates back to 1979, with the introduction of a mechanism in Unix V7 that separated file access for each process and marked the beginning of process isolation.

A more modern implementation came in 2000 when FreeBSD created “jails,” which partitioned a FreeBSD computer system into several independent, smaller systems with the ability to assign an IP address for each system and configuration. Then in 2004, the first public beta of Solaris Containers was released, which combined system resource controls and boundary separation provided by zones.

In 2005, Open VZ was launched, which provided operating system-level virtualization for Linux, using a patched Linux kernel for virtualization, isolation, resource management, and checkpointing. Google introduced Process Containers in 2006 for limiting, accounting, and isolating resource usage of a collection of processes. It was renamed Control Groups (or cgroups) a year later and eventually merged into the Linux kernel 2.6.24, a major turning point in the evolutionary journey of containerisation.

In 2008, LXC (or Linux Containers) was created as a complete implementation of a Linux container manager, using cgroups and Linux namespaces under the hood. CloudFoundry entered the container space with Warden, which was LXC-based and could isolate environments on any operating system, running as a daemon and providing an API for container management.

The Let Me Contain That for You (LMCTFY) project is also noteworthy. LMCTFY was Google’s open-source solution for containerisation, active deployment of which stopped in 2015 after Google started contributing core LMCTFY concepts to libcontainer, which is now part of the Open Container Foundation. Docker began operations in 2013, and its growth in adoption goes hand-in-hand with the growth of containerisation tools.

While the exact architecture may differ between implementations, containers generally share the same operating system kernel and isolate application processes from the rest of the system. Each container runs as a sandboxed environment, enabling isolation and parallelisation.

To ensure interoperability of container technologies, three major standards have been introduced: the OCI Image, Distribution, and Runtime specifications. The Open Container Initiative (OCI), sponsored by industry giants like Docker, AWS, Google, IBM, and Microsoft, is a project by the Linux Foundation to develop industry standards for a container format and container runtime software for all platforms. The OCI standards were based on Docker’s containerisation technology, and Docker donated about 5 percent of its codebase to get the project off the ground. All of these companies are working towards an open, industry-standardisation of container technologies.

Containers have come a long way since their inception, and they continue to play a significant role in the world of digital engineering. With their lightweight, scalable, and secure nature, containers have become an essential tool for developers looking to create, deploy, and manage applications in a more efficient and effective way. As new innovations and tools continue to emerge, we can expect containers to continue to evolve and improve, driving even greater innovation in the digital engineering space.

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