The short version: containerisation is a method of deploying software that compiles an application together with all its supporting files and libraries into a single package.
With containerisation, a single software package (or container) can be created that's compatible with a wide variety of environments.Why do we need containers?
Containers provide a kind of logical packaging that separates programs from their physical hosting environment. Because of this separation, container-based apps can be reliably deployed in the same way, whether they're destined for a private data centre, the public cloud or even the developer's laptop.
Agile development: by eliminating dependency- and environment-related worries, containers boost development velocity.
Operating efficiency: because of their small footprint, containers only use the system resources that are really being used. Programs may function more smoothly as a result.
Run anywhere: there's seldom a limitation on where you can deploy a container. Containers allow you to execute applications in almost any environment.
Containerisation vs virtual machines
Exactly how do containers stack up against virtual machines (VMs)? Let's start by defining what a VM is.
A VM is an abstract representation of a fully operational computer system. Although the hypervisor often virtualises the underlying hardware of the virtual machine, the VM itself is typically unaware that it's operating on a simulated platform.
Considering that a virtual machine has its own operating system, programs, drivers and ancillary software, it's substantially bigger than a container. Operating system licensing, lifecycle management and configuration drift management are just a few of the numerous operational duties that must be performed on virtual machines to guarantee they are in complete compliance with the agreed-upon set of corporate governance principles.
Containers provide the appealing benefit of portability across container hosts without requiring the user to worry about changing any dependencies.
When using a conventional virtual machine, it's your responsibility to ensure that your application's requirements, components and other parts are properly set up. However, with a container, the program itself is packaged together with any necessary dependencies.
This means developers and IT ops can relocate apps and schedule containers to run on any container host with significantly less effort since all prerequisites and dependencies are transferred along with the container.
Virtual machines provide a far greater challenge for lifecycle management because they're often kept running for the whole of an application's lifecycle, including any updates. As a consequence, the virtual machine may include outdated software, improperly installed applications or other unwanted extras. Virtual machine security upgrades are another responsibility that falls on organisations' shoulders.
Containers facilitate idempotency adoption in businesses. Once the current application version has been deployed, the containers executing it will not be updated. Instead, organisations can deploy brand-new containers pre-loaded with the latest version of each containerised program. Every time a container is deployed, a brand-new application environment is created.
More benefits of containerisation
From what we've learned, we can conclude that applications can be containerised to include just the components they need – and then deployed to any environment with a container engine.
Considering this, the key advantages of containerisation become clear. They include:
1. Separation of responsibility
With containerisation, developers can concentrate on the business logic and dependencies of an application, while IT operations can handle the deployment and administration without worrying about the nitty-gritty of the program and its setup.
2. Workload mobility
Containers can be deployed on many platforms, making development and deployment much simpler. For instance, a containerised application could run on:
- Virtual machines or real servers
- A developer's local workstation
- On-premise data centres
- And, of course, the public cloud
3. Speed
Containers typically boot far more quickly than virtual machines or bare-metal servers. Virtual machines may take several minutes to boot up, but containers can be up and running in a matter of seconds.
4. Efficiency
Containers are much more efficient than virtual machines due to their minimal overheads – after all, they include only what is necessary to operate a program.
The typical size of a container is measured in megabytes, whereas that of a virtual machine is measured in gigabytes. Because of this, teams may make better use of server resources by using containers.
5. Easy implementation
Due to their small size and low weight, containers can be quickly moved to any location. Any system capable of running the underlying container engine will also be capable of running the containerised application.
6. Security
Because containers isolate programs, harmful malware cannot spread from one container to another or to the host operating system. Security permissions may also be set up to prevent unauthorised components from entering containers or restrict interactions with resources that aren't essential.
Conclusion
We've spent a lot of time comparing VMs with containers. But this isn't to say that firms have to choose between the two. Organisations may choose to use containers alongside virtual machines to harness the benefits of both models. Using VMware's
vSphere with Tanzu, for instance, allows you to run containerised Kubernetes workloads side-by-side with standard VM-based applications.

Ascend Cloud Solutions is a
cloud computing consultancy and migration firm based in Cork, Ireland. We help accelerate your ambition with tailored, solution-driven advice delivered by trusted VMware experts. Want to talk cloud strategy?
Contact our cloud computing specialists today.
