Docker container Vs Virtual Machine(VM) Key differences
Both vm and docker help replicate development environment, and manage dependencies and configurations better.
Challenges in Application development and Deployment
When you work as part of a development team, each application requires installation of multiple third-party software and packages. In order to collaborate and work together, every developer on the team should configure their local development environment.
However, setting up the development environment is a tedious process. The installation steps can be potentially different depending on the operating system and system configuration. Even during deployment, you have to configure the same environment on the server.
To address the above challenges, it really helps if the applications run in isolated environments that you can replicate easily — independent of the system configuration. Both Virtual Machines (VMs) and Docker containers help you achieve this.
How Does a Virtual Machine Work?
A Virtual Machine or VM is the emulation of a physical computer inside a host machine.
How Does a Docker Container Work?
A docker container is a portable unit of software — that has the application — along with the associated dependency and configuration.
Unlike a VM, Docker containers do not boot up their own guest OS. Rather, they run on top of the host operating system. This is facilitated by a container engine.
Docker vs VM — A Comprehensive Comparison
- Virtualization
- Compatibility
- Size
- Performance
- Security
- Replicability
️1️⃣ Virtualization
From our understanding thus far, both virtual machines and Docker containers provide isolated environments to run applications. The key difference between the two is in how they facilitate this isolation.
Recall that a VM boots up its own guest OS. Therefore, it virtualizes both the operating system kernel and the application layer.
A Docker container virtualizes only the application layer, and runs on top of the host operating system.
2️⃣. Compatibility
A virtual machine uses its own operating system and is independent of the host operating system that it’s running on. Therefore, a VM is compatible with all operating systems.
A Docker container, on the other hand, is compatible with any Linux distribution. You may run into some problems running Docker on a Windows machine or an older Mac.
3️⃣. Size
A Docker image is lightweight and is typically in the order of kilobytes. A VM instance can be as large as a few gigabytes or even terabytes.
4️⃣. Performance
In terms of performance, Docker containers provide near-native performance. Because they are lightweight, you can start them in a few milliseconds.
Starting a VM is equivalent to setting up a standalone machine inside your computer. It can take as long as a few minutes to start a VM instance.
5️⃣. Security
Docker containers run on top of the host operating system. Therefore, if the host OS is susceptible to security vulnerabilities, so are the Docker containers.
Virtual machines, on the other hand, boot up their own operating system, and are more secure.
Recall: each virtual machine is a fully blown machine running inside another. If you have stringent security constraints to be met for sensitive applications, you should consider using a virtual machine instead.
6️⃣. Replicability
The next factor we’ll consider is the ease with which you can replicate the isolated environments provided by VMs and containers. We can infer the ease of replicability from our earlier discussions on size and performance.
When there are multiple applications, each of which should run on a VM instance, using VMs can be inefficient and resource intensive. Docker containers, by virtue of being lightweight and performant, are preferred when you need to run multiple applications.
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