In the world of software development, choosing the right way to deploy applications is crucial. Two of the most prominent technologies in this area are Docker and virtual machines (VMs), each with its own characteristics and advantages. Understanding the differences and similarities between these solutions can help developers and software architects make informed decisions about the best way to manage their applications and resources.
What are Docker and Virtual Machines?
Docker is an open-source platform that allows developers to package applications into standardized units known as containers. These containers include the application code as well as its environment, which encompasses libraries and system tools, ensuring that applications run consistently across different environments.
On the other hand, virtual machines represent a digital copy of a physical machine, allowing multiple independent operating systems to run on the same hardware. Each virtual machine operates with its own operating system, providing a completely isolated environment. Additionally, it is possible to run Docker containers on virtual machines, providing flexibility in deployment.
Virtualization: Comparison between Docker and Virtual Machines
Virtualization is a technique that enables the creation of virtual instances of physical resources, such as servers and networks. For example, it is possible to run multiple virtual servers on a single physical server. This technology maximizes the utilization of physical resources, leading to more efficient management and reduced costs. Therefore, virtualization is fundamental for the development and deployment of applications in today's technological infrastructure.
Virtual Machines
Virtual machines provide full emulation of a physical machine, including CPU, memory, networks, and storage. They allow a guest operating system and various applications to run in a virtual environment. Thanks to this technology, cloud solutions like Amazon Web Services (AWS) have been developed, where a virtual machine is known as an instance.
Docker
Unlike virtual machines, which require hardware emulation, Docker operates in containers that are isolated instances of user space. This means that Docker allows applications to run without the need for a complete operating system, directly utilizing the underlying operating system's kernel.
Similarities between Docker and Virtual Machines
Although Docker and virtual machines have different approaches, they share some notable similarities:
Images
Both Docker containers and virtual machines are created from images. These images establish a blueprint of the virtualized environment, allowing for the creation and sharing of consistent environments without the need to configure them each time. The images specify the system resources required to run applications, where, for example, a traditional VM image backs the operating system, while a Docker image backs the application environment.
Version Control
Both Docker images and virtual machine images can be extremely useful in tracking changes over time. In Docker, this facilitates the management of different versions of applications, allowing developers to revert to previous versions or run different versions in parallel. In virtual machines, version control involves tracking virtual hardware configurations and operating systems as they evolve.
Portability
Both technologies aim to improve the portability of applications by addressing the challenges of diverse hardware and different architectures. Both Docker images and virtual machine images are designed to be easily moved, whether in local installations or cloud environments.
Essential Differences between Docker and Virtual Machines
Despite their similarities, Docker and virtual machines address the problem of application execution in different ways, with different goals.
Objectives
Virtual machines are primarily designed to allow multiple operating systems to run on a single physical machine. This results in a virtual environment that is isolated from the underlying hardware and allows for efficient utilization of hardware resources.
In contrast, Docker aims to provide a lightweight and portable solution for packaging and running applications in an isolated and reproducible manner, simplifying the deployment process across various environments.
Final Product
Docker refers to the container platform created by the company Docker, which has become a benchmark in containerization. While there are alternative platforms like Podman, Docker remains the most recognized option. In this sense, the container is the usable artifact by the end-user.
On the other hand, virtual machines are not tied to a specific brand and can be implemented in various environments, whether in local data centers or cloud solutions.
Architecture
Virtual machines function by running their own kernel and operating system, in addition to applications and their dependencies, managed by a hypervisor that coordinates the underlying hardware. Multiple virtual machines can exist on a single server, each operating independently.
Docker containers, on the other hand, only include their dependencies and rely on the Docker Engine for virtualization, offering greater efficiency by sharing the underlying operating system's kernel.
Resource Sharing
Both technologies can optimize resource utilization, albeit in different ways. Virtual machines allocate a defined amount of resources during their configuration, while Docker containers use resources dynamically based on what they need at the moment, allowing for greater overall efficiency.
Security
In terms of security, virtual machines tend to offer greater isolation by running a full operating system. This means that, if proper security measures are maintained, they are less vulnerable. Conversely, Docker containers share the operating system's kernel, which presents a risk in case vulnerabilities in the kernel are discovered. However, Docker also implements advanced security controls to mitigate these risks.
When to Use Docker and When to Use Virtual Machines
The choice between Docker and virtual machines depends on the specific needs of the application to be implemented.
Use of Virtual Machines
It is advisable to opt for virtual machines if the application has the following characteristics:
- Strict operating system dependencies.
- Significant hardware resource requirements.
- Need to manage multiple controls across operating systems.
- Legacy applications that do not work on modern operating systems.
- Various operating system requirements within the same physical infrastructure.
Use of Docker
On the other hand, Docker is ideal in the following cases:
- Lightweight resource requirements typical of microservices architectures.
- Distributed physical infrastructure, including cloud environments.
- Fast deployment cycles, as Dockerfiles are easier to manage than VM configurations.
- Needs for rapid scalability.
Summary of Differences: Docker vs. Virtual Machines
Aspect Docker Containers Virtual Machines
| How it works | Platform for creating and running Docker containers | Emulation of a physical machine with its own OS
| Virtualization | Uses OS-level details from the code | Uses hardware-based details from the code
| Objective | Increase hardware utilization | Improve application environment management
| Managed by | Docker Engine coordinates OS and containers | Hypervisor coordinates physical hardware and VMs
| Architecture | Shares host OS resources | Runs its own kernel and operating system
| Resource Sharing | On-demand usage | Fixed predetermined amount
Both technologies play a fundamental role in application development, and their choice will depend on the specific needs of the project. For more information on related topics and to continue exploring the world of virtualization and software development, readers are invited to visit the blog.
