Docker is indeed a powerful technology, but choosing it may not be the right decision for every workload. Because of this reason, we have decided to compare Docker with Virtual Machines to know the best decision to make at every workload. Before we dive into that, let’s take a brief look at each of them.

Docker vs. VMs in a nutshell

Docker vs. VMs in a nutshell

Docker vs. VMs in a nutshell

Let’s first look into what both of them have in common before looking into their differences.Both Docker and Virtual Machines container can be applied inside environment that is separate from the underlying hardware (the only difference is the level of separation). On the Virtual Machines, everything running inside the machine does not depend on the host operating system. However, the way Docker handles storage is compared to how you persist data within the Virtual Machines (this feature is not really important to someone who is considering whether to use Docker or Virtual Machines).Without saying much, let’s now look at the advantages of Docker over Virtual Machines and vice versa.

When to use Docker

Docker is a better choice over Virtual Machines under the following workloads:

Start time

It only takes a few seconds for a Docker to start while it takes minutes to start a Virtual Machine. Thus, workloads need to start very quickly.

Efficiency

Docker containers share many of its properties with the host system, thus the only thing that needed to be installed for it to start operating compare to a Virtual Machine that takes up less space and consumes less RAM and CPU time. The container can help you save some money on using cloud computing to save your data.

Licensing

The core technologies used nowadays require Docker container for it to run. The container runtimes are designed like Kubernetes, which is free and can be sourced around. This saves costs and increases flexibility.

Code reuse

Docker container largely depends on the container image, which consists of the data and instructions that the container need for it to run a particular application. Docker containers can be downloaded, reuse, and easily share using container registries, unlike the Virtual Machine which can also be shared, but those images are typically too large to be shared, and they usually include operating systems.

When is it right to stick to Virtual Machines?

When is it right to stick to Virtual Machines?

When is it right to stick to Virtual Machines

Now that we’ve seen some of the amazing features of Docker, let’s see if there are any reasons why Virtual Machines may be considered.

Ease of deployment and management

Virtual machines are easier to install and manage than Docker containers, simply because Virtual Machines have fewer moving parts. By simply installing your hypervisor, your Virtual Machine is ready for use.In the case of Docker, you have to install Docker itself, then pull container images, and start each image separately.

Security

This article will not be able to discuss in detail the security merits of Virtual Machines as compared to Docker. However, let’s just take a glance at it. Virtual Machines are more isolated from each other and from the host system than Docker containers. Because of this reason, Virtual Machine doesn’t directly share any kernels or other resources with the host system which makes it more secure compared to Docker.

Portability

Most Virtual Machine platforms are designed to work on every major operating system. Thus, you can deploy a Windows Virtual Machine on Linux or vice versa. This portability is useful if you have an infrastructure where you need to deploy one type of operating system on another. Docker doesn’t provide portability across operating systems. Docker containers for Linux only work on Linux hosts, and the same holds true for Windows.

Predictability

The big disruption in the world of Virtual Machines was the entry of KVM as a production-quality solution about a decade ago. Virtual Machine software and strategies that worked circa 2001 are still viable today. Virtual Machines, in this sense, are a very predictable, stable technology. This is not the same in Docker.

Conclusion

Docker is a powerful technology with amazing features which makes it possible to deploy applications on a lower level resource consumption and faster than Virtual Machines. On the other hand, Virtual Machines have continually developed killer features such as a higher degree of portability and full support for image rollbacks.