Introduction
Containerisation is the packaging of software code with just the operating system (OS) libraries and dependencies required to run the code to create a single lightweight executable—called a container—that runs consistently on any infrastructure. More portable and resource-efficient than virtual machines (VMs), containers have become the de facto compute units of modern cloud-native applications.
The Concept of Containerisation
With traditional methods, developers write code in a specific computing environment, which, when transferred to a new location, often results in bugs and errors. Containerisation eliminates this problem by bundling the application code with the related configuration files, libraries, and dependencies required for it to run. This single software package or “container” is abstracted away from the host operating system. Hence, it stands alone and becomes portable—able to run across any platform or cloud, free of issues. This is because the container shares the machine’s operating system kernel and does not require the overhead of associating an operating system within each application. In the case of Linux and non-Hyper-V containers, the Host OS shares its kernel with running Docker containers. For Hyper-V each container has its own Hyper-V kernel.
The concept of containerisation and process isolation is decades old. However, the emergence in 2013 of the open-source Docker—an industry standard for containers with simple developer tools and a universal packaging approach—accelerated the adoption of this technology.
This approach allows developers to create and deploy applications faster and more securely. It also enables applications to be “written once and run anywhere” across on-premises data center, hybrid cloud, and multi-cloud environments. This portability speeds development, prevents cloud vendor lock-in, and offers other notable benefits like fault isolation, ease of management, simplified security, and more.
Benefits of Containerisation
Portability: Software developers use containerisation to deploy applications in multiple environments without rewriting the program code. They build an application once and deploy it on multiple operating systems.
Scalability: Containers are lightweight software components that run efficiently. For example, a virtual machine can launch a containerised application faster because it doesn’t need to boot an operating system. Therefore, software developers can easily add multiple containers for different applications on a single machine.
Fault Tolerance: Software development teams use containers to build fault-tolerant applications. They use multiple containers to run microservices on the cloud. Because containerised microservices operate in isolated user spaces, a single faulty container doesn’t affect the other containers. This increases the resilience and availability of the application.
Agility: Containerised applications run in isolated computing environments. Software developers can troubleshoot and change the application code without interfering with the operating system, hardware, or other application services. They can shorten software release cycles and work on updates quickly with the container model.
Efficiency: Containers are more resource-efficient than virtual machines, as they share the host system’s kernel, and don’t require a full operating system per application.
Consistency: Containers ensure consistency across multiple development, testing, and production environments. This means that you can avoid the common problem of an application working on one environment but not on another.
Use Cases of Containerisation
Cloud Migration: Cloud migration, or the lift-and-shift approach, is a software strategy that involves encapsulating legacy applications in containers and deploying them in a cloud computing environment. Organisations can modernise their applications without rewriting the entire software code.
Adoption of Microservice Architecture: Organisations seeking to build cloud applications with microservices require containerisation technology. The microservice architecture is a software development approach that uses multiple, interdependent software components to deliver a functional application.
Continuous Integration and Continuous Deployment (CI/CD): Containers are integral to CI/CD pipelines. Developers can package their applications with all their dependencies into a container, which can then be continuously integrated and deployed, ensuring that the application works seamlessly in different environments.
Isolation of Applications: Containers ensure that each application and its runtime environment are isolated from each other. This means that you can have multiple applications, each with its own set of dependencies, running on a single machine without any conflicts.
Scalability: Containers can be easily and quickly started or stopped, making it easy to scale applications up and down based on demand. This is particularly useful in a microservices architecture, where different services may need to be scaled at different rates.
Development and Testing: Containers provide a consistent environment for development, testing, and production. This means that developers can be confident that if their code works in their local container, it will work in any other environment.
Conclusion
Containerisation is revolutionising the way we develop, deploy, and manage applications. Its benefits of portability, scalability, fault tolerance, and agility make it an essential tool in the modern software development landscape. As more organisations continue to adopt this technology, we can expect to see even more innovative uses and advancements in the field of containerisation.