Docker vs VMs

Updated June 12, 2023

Difference between Docker vs VMs

Here is an introduction to Docker vs Virtual Machines (VMs):

Docker containers have numerous tags and are designed to promote cloud portability by allowing the same applications to run in different virtual environments. Docker is an open platform for developers. It isolates the dependencies of each application by packaging them into a container. Containers are safer and more scalable comparatively.

Virtual machines (VMs) are widely used in cloud computing for resource control and isolation. VMs load a complete operating system along with their own memory management, thereby making applications more secure and efficient without risking high availability. This is accomplished by emulating all the necessary resources for the hypervisor and guest operating system. Multiple instances can be hosted on a single machine in parallel, with each guest OS running as an individual entity from the host system.

Docker vs VMs: Head-to-head Comparison (Infographics)

Here are the top 6 differences between Docker and VMs:

Detailed Differences between Docker and VMs

Docker containers use the Docker engine to run a single application across different operating systems. This is achieved using container images that are ready to be deployed quickly. On the other hand, VMs use a hypervisor—a combination of firmware, software, and hardware, also known as a virtual machine monitor (VMM)—to present a virtual operating platform to guest operating systems. This allows multiple instances from different operating systems to share virtualized hardware resources on a single physical x86-based machine.

Docker containers lack isolation when compared to VMs. Intel’s VT-x and VT-d technologies provide ring-1 isolation for their VMs, which prevents them from clashing or interfering with each other’s workings. Since Docker containers do not have this isolation mechanism, it is more vulnerable to exploits.

Containers are fast, secure, lightweight, and suitable for application deployment—as long as the user sticks with a single platform to provide a shared operating system. They can launch in seconds, whereas VMs may take several minutes to launch. Containers offer superior performance compared to running an application inside a VM.

Most digitally-operational companies are moving away from VMs as their primary choice and opting for containers instead. In VMs, application deployment can be time-consuming and running microservices can be a challenge. Some companies, e.g., Starling Digital Bank, still use VMs over Docker. However, most companies interested in enterprise-grade security for their infrastructure prefer using Dockers.

Docker vs VMs: Comparison Table

Below is a brief comparison between Docker vs VMs:

Basis of Comparison	Dockers	Virtual Machines
Boot-Time	Dockers can boot in seconds	It often takes minutes for VMs to boot
Execution	Makes use of an execution engine	Makes use of a hypervisor
Memory	More memory efficient as no space is needed to virtualize	Less memory efficient as the entire OS needs to be loaded before starting the service
Isolation	No provision for isolation of systems and hence are more prone to problems.	Efficient isolation mechanism reduce the interference possibilities.
Ease of Deployment	Deploying through Dockers is extremely easy, as only one image, containerized, can be used across different operating systems.	Deploying in Virtual Machines is a comparatively lengthy process, where separate instances are responsible for the execution.
Ease of Usage	Dockers have a comparatively complex usage mechanism that consists of both third-party and docker-managed tools.	The tools associated with a VM are comparatively easier to use and work with.

Conclusion

Dockers are quickly gaining popularity, but there are some use cases where virtual machines are still a better choice. For instance, virtual machines are more appropriate for production environments when compared with Docker containers. Thus, Docker is not a replacement for virtual machines, but rather an add-on—at least for now. It’s important to consider a company’s architecture and application needs before deciding what to adopt.

Docker containers use a Docker engine instead of a hypervisor, allowing containers to be small, less isolated, more compatible, and more performance-intensive than virtual machines. Containers can share a single kernel and application libraries, and their overhead is lower than that of virtual machines. Many companies today are using a hybrid approach, choosing between Docker and virtual machines based on the workload and application design.

Recommended Articles

Here are some further comparison articles to increase your knowledge:

1. Oracle vs OpenJDK | Differences
2. Rails vs PHP | Comparison
3. Difference Between AWS vs AZURE
4. Controller vs Comptroller