What Is Containerization?
In the world of computing, containerization is a term that has gained huge attention and popularity in recent years. A container is a lightweight alternative to full machine virtualization, which involves encapsulating an application in an isolated operating environment, with all the files and libraries it needs to operate. Every containerized application can share the host system’s user space, while still maintaining its individual system processes, environment variables, and libraries.
Containerization offers a range of benefits, including rapid deployment, portability, and scalability. It allows developers to create predictable environments that are isolated from other applications, reducing the risk of system instability or conflicts between applications. It also enables them to package their software with all of its dependencies, which can then be run on any system running a container engine, regardless of its specific configuration.
Furthermore, containerization supports the microservices architecture, where applications are broken down into small, independent services. This approach allows for faster and more reliable deployment, and more effective management of complex applications.
What Is Virtualization?
Virtualization is a process of creating an abstraction layer over hardware, allowing a single computer to be divided into multiple virtual computers. Each of those virtual computers (known as “guests”) uses part of the hardware resources of the main computer (known as a “host”).
The software used to achieve this is a hypervisor. Hypervisors run on a host operating system and enable multiple guest operating systems to run on top of it, sharing the same physical computing resources managed by the host operating system. In essence, this allows the physical computer to abstract the operating system and applications from the hardware.
This is part of a series of articles about docker container.
In this article:
- Containerization vs. Virtualization: Key Differences
- Use Cases for Virtualization
- Use Cases for Containerization
Containerization vs. Virtualization: Key Differences
1. Resource Overhead
When comparing containerization vs virtualization in terms of resource overhead, containerization is the clear winner. Because containers share the host system’s operating system, and do not need to run a full operating system, they are significantly more lightweight and consume fewer resources. Virtual machines, on the other hand, each require their own OS, which increases the overhead, especially when many VMs are running on the same host system.
2. Startup Time
In general, containers start up more quickly than VMs, because they don’t have to start up an entire operating system. Virtual machines take much longer to boot up. This means containers are more flexible and can be torn down and restarted whenever needed, supporting immutability, which means that a resource never changes after being deployed.
3. Portability
Both containers and virtual machines offer a high degree of portability. However, containers have a slight edge because they package the application and all of its dependencies together into a single unit, which can be run on any system that supports the container platform. Virtual machines, while also portable, are more dependent on the underlying hardware.
4. Security Isolation
In terms of security isolation, virtual machines have the advantage. Because each VM is completely isolated from the host system and other VMs, a security breach in one VM typically does not affect the others (although it is possible to compromise the hypervisor and take control of all VMs on the device). Containers, while isolated from each other, still share the host system’s OS, so a breach in one container could possibly leak to other containers.
5. Scalability and Management
The lightweight nature and rapid startup time offered by containers make them ideal for scaling applications quickly and efficiently. They also lend themselves well to the microservices architecture, which can simplify the management of complex applications. Virtual machines, while also scalable, are more resource-intensive and take longer to start, making them less suitable for microservices and distributed applications.
Related content: Read our guide to what is a container
Use Cases for Virtualization
Here are some of the main use cases of virtualization technology:
Legacy Applications
In the world of software, legacy applications are often seen as a burden. These are applications that were built using older technologies and are typically difficult to maintain or upgrade. However, they are often critical to business operations and cannot simply be discarded. This is where virtualization shines.
Virtualization allows these legacy applications to continue running on their original operating systems, even when the underlying hardware has been upgraded. This means that businesses can continue to use these applications without the need for expensive and time-consuming upgrades. Furthermore, virtualization provides a sandboxed environment, protecting the rest of the system from potential vulnerabilities in these older applications.
Environments Needing Strong Isolation
Virtualization also excels in environments where strong isolation between applications is critical. This is particularly useful in high-security environments, where a breach in one application should not be able to affect others.
For instance, in a data center serving multiple organizations, virtualization can be used to isolate applications belonging to different users from each other. Even if one user’s application is compromised, the attacker would not be able to access applications running on other virtual machines.
IaaS Scenarios
Infrastructure as a Service (IaaS) is a cloud computing model where resources like virtual machines, storage, and networks are provided as a service. Virtualization is a core technology behind IaaS. It allows cloud providers to efficiently utilize their hardware resources by running multiple VMs on the same physical hardware.
Additionally, virtualization provides the flexibility to scale resources according to demand. If a client needs more resources, they can easily be allocated more virtual machines.
Use Cases for Containerization
Here are the main use cases for containerized applications:
Microservices Architectures
One of the main use cases for containerization is in microservices architectures. In a microservices architecture, an application is broken down into small, independent services that communicate with each other. This approach has many benefits, including improved scalability and easier maintenance.
Containers are a perfect fit for microservices. They provide a standardized environment for each service, ensuring that they run consistently across different platforms. Additionally, containers are isolated from each other, which prevents conflicts between services or service instances.
CI/CD
Continuous Integration/Continuous Deployment (CI/CD) is a software development practice where developers integrate their code into a shared repository frequently, usually several times a day. Each integration is then automatically tested and deployed. This approach allows teams to detect and fix problems early, resulting in higher quality software.
Containerization plays a crucial role in CI/CD. Containers provide a consistent environment for testing, ensuring that tests are reliable and repeatable. Furthermore, containers can be easily deployed to production, making the deployment process faster and more efficient.
PaaS Scenarios
Platform as a Service (PaaS) is a cloud computing model where a provider delivers a platform for developers to build, test, and deploy applications. This platform typically includes an operating system, middleware, and runtime environment.
Containerization is an integral part of PaaS. It allows providers to efficiently utilize their resources by running multiple containers on the same host. Additionally, it provides a standardized environment for developers, making it easier for them to build and deploy applications.
Related content: Read our guide to container DevOps
Conclusion
The debate between containerization vs virtualization is not about which technology is better, but about which is more suitable for a particular use case. Virtualization is a great choice for running legacy applications, providing strong isolation, and in IaaS scenarios. On the other hand, containerization is ideal for microservices architectures, CI/CD, and PaaS scenarios.
As we move into the future, it’s clear that both containerization and virtualization will continue to play a role in the IT and software development environment. By understanding their unique use cases and benefits, businesses can make informed decisions about which technology to adopt and how to best leverage them for their needs.
