With development teams needing a fast and reliable way of building, testing, maintaining, and scaling applications, container-based software development, or containerisation, has exploded in recent years. So much so that it’s predicted that over 75% of organisations worldwide will be running containerised applications going into 2023 – up from less than 30% in 2020.
But what are containers and how can they help your organisation develop digital solutions faster and more efficiently? Let’s take a look below.
What Are Containers?
Containers are packaged applications that contain all the necessary components, including code, dependencies, libraries, and configuration files, to run in any environment. By isolating applications from the environment in which they’re run, containers allow applications to be deployed easily while requiring fewer resources, such as CPU usage, memory, and storage.
Because containers allow applications to be developed as a series of small, independent components, as opposed to a single program (i.e., monolithic software), developers can build, deploy, maintain, update, and scale applications more quickly and efficiently.
Containers vs Virtual Machines (VMs)
Whenever discussing containers, the subject of virtual machines (VMs) is bound to come up. However, although they share some similarities, namely, that both technologies utilise virtualisation, containers work differently from VMs.
A VM is an application that’s installed on physical hardware, such as a server, and emulates a computer. While its host machine will have its own operating system (OS), VMs also contain their own guest OS, as well as the code, binaries, libraries, and other files they need to run their applications. Additionally, VMs sit on an application layer called a hypervisor, which virtualises the resources from its host machine and allocates them to VMs.
Containers, in contrast, don’t house an OS: instead, they sit on top of a container engine that virtualises the host machine’s OS, allowing them to run anywhere. As a result, containers are much smaller than VMs – only requiring megabytes of storage instead of gigabytes. Subsequently, containers are less resource intensive, start faster than VMs, and can be transferred between environments with far greater ease.
The Pros and Cons of Containers
Let’s explore the advantages and disadvantages of containerisation.
- Portability: Containers provide a lightweight and isolated infrastructure to move applications between different environments, i.e., development, test, production, clouds, physical servers, , while retaining full functionality. The increased portability offered by containerisation accelerates development, testing, and production cycles.
- Efficiency: As they include all the components and dependencies required by the application, containers allow developers to work within more stable runtime environments. Subsequently, they get to spend less time troubleshooting environmental differences and can focus on core functionality and new features.
- Easier to Maintain: Containers break code down into distinct, manageable pieces which can be updated and maintained without impacting other parts of the application.
- Effective Resource Usage: Unlike VMs, containers don’t have their own OS and use fewer system resources as a result. As containers take up less storage space, you can run far more containers than VMs on a server.
- Scalability: Containers make it simple to scale distributed applications. This is because you can deploy additional identical containers to create more instances of the application you want to scale – rather than entire instances of the full application.
- Lower Costs: Because containers use resources more efficiently, can be run in cost-effective cloud environments, and are easier to maintain, they can help organisations reduce their IT spend.
- Not Suitable for All Software: Applications that can be designed to run as a series of microservices benefit most from containerisation. In contrast, some software, that doesn’t need to be scaled or deployed quickly, can be developed to have a monolithic architecture – and containerisation would just increase its complexity.
- Persistent Storage: Persistent data storage is complicated in containers as, by design, the data within them disappears when the application instance is shut down, so software that relies on persistent data will need an external storage mechanism. Subsequently, this is handled by a container orchestrator.
- Increased Monitoring Requirements: Containers are typically used to develop multi-layered infrastructure, so this requires you having to monitor more components than if you were running your applications on VMs, for instance.
What are Container Platforms?
As applications can be comprised of hundreds, or even thousands, of containers, manually configuring each one is unfeasible. So, to rapidly accelerate the deployment and management of containerised apps, companies also need to utilise container platforms.
Container platforms are software that allows development and operation teams to build and maintain containerised applications, automating the deployment, management, scaling, and networking of containers. The two most widely used and highly regarded container platforms are Docker and Kubernetes.
Docker is a container engine, or runtime environment, that lets you package applications into containers, run them, and deploy them to multiple, different environments. Docker turns applications into container images before pushing them onto a registry, where they can be stored for later deployment.
However, Docker is insufficient for managing the hundreds to thousands of separate containers that an application could require in production. As a result, container runtime environments like Docker need an additional platform to manage the containers – which is where Kubernetes comes in.
Kubernetes is a container orchestrator: software designed to manage containerised applications across a distributed network, whilst hiding the complexity of the task. Kubernetes works with container runtime environments, like Docker, to allow teams to manage every aspect of their containerised architecture, including:
- Scheduling and running containers on clusters of physical servers or VMs
- Orchestrating containers across multiple hosts
- Providing a runtime platform for cloud-native applications
- Optimising usage of system and network resources
- Automating and controlling app deployments and updates
- Scaling applications
When Should You Use Containers?
A microservices architecture breaks down applications into independent, individually deployed services. The most significant benefit offered by microservices is simplicity, as their design approach allows complex applications to be developed quickly and reliably. A microservices architecture is also easier to maintain as each isolated service can be scaled or updated without disrupting other services.
Containers provide the ideal deployment unit and self-contained execution environment for microservice-based applications. They allow you to run different parts of an app as independent services that communicate through lightweight protocols and give you greater granular control over individual components.
Developers can use containers to refactor legacy applications into a microservices architecture before migrating them to the cloud. While this takes longer than simply migrating the application as it is, i.e., a “lift-and-shift” migration, the app will receive the full benefits of containerisation and the cloud environment. Similarly, a microservices architecture is ideal for developing new cloud-native applications, as can provide the flexibility, manageability, and resilience expected from software running in a cloud environment.
DevOps and CI/CD
Containers complement agile DevOps methodologies so well because they are lightweight, can be consistently deployed in multiple environments, and can be isolated. This makes containers easy to automatically build, test, deploy, run, troubleshoot, update and fix in the shorter development lifecycles required for CI/CD.
With the rapid rate of digital transformation worldwide, and organisations predicted to invest a staggering $6.8 trillion on digital innovation in 2023, its little surprise containers are fast becoming a mainstream technology.
Containerisation helps organisations accelerate their migration into the cloud, allows them to scale applications efficiently, and, perhaps most importantly, overcome the persistent challenge of deploying quick and reliable releases and updates. Subsequently, containerisation not only gives companies a way of developing more performant software faster but also provides a way of efficiently managing applications as they grow in both size and complexity.
As growing numbers of companies benefit from enhanced operational efficiency and reduced costs of container-based development, containers will inevitably become the default method of implementing digital transformation strategies.