While both virtual machines and Docker containers are an emulation of a computer system that uses special software loaded on a computer to deploy apps and programs, the 2 are completely different from each other. Virtual machines date ages back and provide the functionality of a physical computer. In contrast, Docker is a new platform that has been recently developed and uses operating system-level virtualization. Though Virtual machines have been a great companion for those in the IT field, Docker soon after its development, has been humming praise by the developers because of its technology. Before making the comparison, let’s know the basics and the similarities between the two:
What is Docker?
It is a software development tool that uses OS-level virtualization to build, deploy and ship different software tools and brings a more secure, portable, and autonomous supply chain into applications and other micro-services.
With the growing digital world, every business organization is transforming digitally but often gets constrained by diverse portfolios of applications, cloud, and much more.
Docker comes up with an effective solution in the form of containerization that automates the application deployment on various operating systems, like Windows and Linux via a secure supply chain. In simple terms, applications run the same on every machine/ platform irrespective of any dependencies on the local operating system.
History
Docker was founded by Kamel Founadi, Solomon Hykes, and Sebastien Pahl back in 2010 and launched in 2011. Hykes started the project first as an internal project within dotCloud, a platform-as-a-service company. At the start of the year 2013, Docker was debuted to the public in Santa Clara at Pycon and then released as open-source in March. However, in 2017, the Moby project was created by Docker for open research. At first, Docker used LCX technology as its default execution environment but that was later replaced with libcontainer.
Features
- Docker can reduce the size of an application by using the footprint of the operating system that is containers.
- With Docker, it gets easy for the team of developers across multiple units for example development, QA, and Operations to work.
- Since Docker uses containers, non-dependent tasks of a process can be separated and run parallel.
- Docker containers can be deployed anywhere- both on physical and virtual machines.
- Docker ensures that the resources and applications are well segregated.
Application
Docker is rapidly being adopted by the leading companies of the world due to its marvelous technology that includes image portability, convenience, and easy development. They look at it as the best solution for cloud-based services or build micro- applications. Since Cloud providers need faster iterations for their applications, Docker seems an intelligent choice. In the case, where Docker represents the micro- application or broader deployment application, It again proves fruitful especially when some components of the app get developed over the cloud and then undergo on-premise deployment. Some of the companies that use Docker technology include- eBay, Spotify, ING, IBM.
Advantages of Using Docker:
- Docker containers are lightweight and hence scalable.
- Docker suits well to clouds.
- East to set up.
- Reliable and easy to maintain.
- Debugging is easy with Docker.
What is a Virtual Machine(VM)?
A virtual machine is termed as a guest machine that is created within a computer or computing environment termed as the host machine. It provides the functionality of a physical computer and is used to run programs that the user does not want to interfere with the host machine giving the end-user the same feel on the VM as they would have had on the host machine.
The virtual machine is isolated from the main machine and more than one virtual machine can be run on the same host machine, however, each virtual machine needs to have its operating system. 4 important types of files make up a virtual machine:
- NVRAM settings file,
- Log files,
- The virtual disk snapshot file, and
- configuration files.
The virtual machine is capable of performing different tasks independently, like testing the operating system and creating back up.
History
Virtual machines date back to the 1960s and continue to be inactive development. Virtual machines grew out of Compatible Time-sharing systems (CTSS) that allowed multiple users to use a computer concurrently. Though each program had full access to the machine, one program was executed at a time. This afterward evolved as virtual machines, notably via IBM’s research system M44 that used partial virtualization and SIMMON that used full virtualization. The first widely available virtual machine architecture was CP- 67.
Features
- Creates a computer within a computer- Virtual machine is a computer file, much like an image that behaves like an actual computer.
- Although, At the same time multiple operating systems that are well separated from each other are offered by Virtual machines yet for multiple operating systems host virtual machines provide features like no dual booting.
- Virtual machines provide encapsulation and the software presented here can be modified and controlled easily.
- Resource provisioning is fast and simple- reduce dependency on additional software and hardware while requiring a different instruction set as that of the host machine.
- Virtual machines are convenient to recover data, an error is one OS does not affect other OS, Fresh Os can be loaded with great ease.
Application
Virtual machines have a wide range of applications like Virtual machines have a huge importance in the testing field, where experts test data retrieved from different sources without compromising the actual machine. For learners, Virtual machines act as a base where users can install different distributions of Linux or other lesser-known operating systems to experiment with them and understand how they work. For software that requires an outdated OS, virtual machines again prove beneficial. Other than these, some other applications of virtual machines include: To run software that was otherwise designed for other OS without any compatibility issue, compiling different servers for business use, and much more.
Advantages
- Offers architecture different from the host machine.
- Easy maintenance.
- Security benefits.
- Centralization of the network and easy management.
- Is cheap in terms of cost.
Similarities between Docker and the Virtual machines:
| Virtual Machine | Docker |
| Processes in one virtual machine and can’t see processes in other virtual machines. | Processes in one Container and can’t see processes in other Containers.. |
| Each Virtual machine has its root file system. | Each Container has its root file system and that is not kernel. |
| Has its virtual network adaptor. | Can get a virtual network adaptor, can have separate IP and ports. |
| Is a running instance of physical files (.VMX, .VMDK). | Is a running instance of Docker images. |
| The host can be different from guest OS. | The host can be different from container OS. |
Docker vs VMs
Let’s compare each technology based on the following factors:
Architecture
The main difference between the two lies in the architecture, the way each of them is implemented. In the case of the virtual machine, the computer system is loaded with two operating systems (OS) – the host OS and the guest OS, where the guest OS can be any OS, like Linux and Windows.
However, with Docker containers, only one operating system is required, and that is of the host. Docker uses the same OS for itself lessening the burden on the machine to boot multiple operating systems. This is possible because Docker uses the concept of containerization.
Containers are lightweight, stand-alone executable code packages that have all the necessary configuration files with them and run directly on the host machine without any need for an additional operating system.
These containers have application-specific libraries and binaries and provide several advantages, such as:
- Reduced IT management resources.
- Reduced size of snapshots.
- Reduced and simple updates.
- Requires less code to be transferred.
In contrast, Virtual machines do not use containers and lack all these advantages. The main use of docker’s architecture is that users can run several applications on the same OS while virtual machines are mainly used for applications that require multiple/ different OS for proper functioning.
Security
VMs have a huge edge over the Docker container system as far as security is concerned. Applications needing more security should run on virtual machines as they stand alone with their kernel and security features making them very strong, isolated to threats.
Containers on the other hand have a shared host kernel that makes them susceptible to attacks. If an attacker gains access to one container in the cluster, the whole system will be compromised because of the docker architecture that allows resources to be shared across, without any namespaces.
The virtual machine never directly allows access to resources but there is a hypervisor that controls the usage of different resources and is thus less susceptible to vulnerabilities, it is because of this reason that VMs are ideal for accessing virus infected data and retrieving information from the same.
Portability
Being isolated from the host OS, VMs cannot be ported across multiple platforms without incurring compatibility issues. Containers on the other hand use host OS and use containers that are self-contained and run applications in any environment.
An application running on docker can easily be ported across multiple platforms. Also, Docker containers being lightweight can be easily deployed in servers and can be started or stopped in very little time as compared to virtual machines.
Resource Requirements
Docker containers are less resource-intensive compared to virtual machines. Containers have comparatively less overhead as they all share the same single kernel as that of the host machine. They also share application libraries. Sharing kernels and libraries means a lesser burden on the memory and thus, are easier to be fetched.
Also, resources like CPU, memory, and input/output devices may not be allocated permanently to containers as is the case in a virtual machine. Containers in Docker could be scaled up a lot easier and are economical on all fronts.
Containers can be updated, deleted, or added in a single step and multiple containers can also run simultaneously on the given host as there is no need to install multiple operating systems in them.
Docker vs Virtual Machines: The Highlights
The main highlights of the differences between Docker and Virtual Machines are:
- A container takes far less time to boot than a virtual machine.
- Only server hardware is virtualized in the case of VMs where each virtual machine has its operating system and applications. In its comparison, Docker uses both the host hardware and software resources only.
- Docker makes use of the execution engine while virtual machines use a hypervisor.
- Less memory space is required in the case of the Docker as the single OS has to be loaded in memory. In contrast, virtual machines consume more memory and are slow to process.
- There is the least interference in the case of virtual machines because of the efficient isolation mechanism which is not true in the case of Docker and is more susceptible to attacks than virtual machines.
- Applications are easy to deploy and build using Docker. Single images can be containerized and then can be used across all platforms. In contrast, VM deployment is comparatively lengthy as separate instances are responsible for execution.
- Docker containers are complex to use, consisting of both third-party and Docker-managed tools while tools are easy to use and simpler to work in virtual machines.
Who is the Better Among the Duo?
Both technologies have their distinct advantages and play an important role in helping drive a lot of businesses to success. One should choose between the 2 depending upon the requirements of his project.
While virtual machines are ideal for those tasks that may otherwise prove risky to host computers or host software, making it ideal to perform risky tasks only on the virtual machine as the software inside the virtual machine cannot temper with host ones.
Beta release testing, running malicious software and accessing the same, emulations of different computer networks, and debugging network errors are some of the functions ideally performed by the virtual machines.
The main advantage of Docker containers is to simplify configurations where a complex mega task can be broken down into simpler easier codes/tasks which can be then saved into different containers. While each container is small, isolated, compatible, high performance-intensive, and quickly responsive, it can run individually and interact with others using container channels.
Thus, a complex task can be performed with much more ease and efficiency in Docker containers. Also, features like Code Pipeline Management, Developer Productivity, App Isolation, and Server Consolidation are some of the great advantages of using Docker.
Conclusion
It will not be right to say that one is better of the other since they have been developed for different uses. They both have their advantages and are intended for different functionalities. Though Docker is gaining momentum these days, there are certain tasks where they stand nowhere close to the benefits of virtual machines. Also, there are cases where a job gets easier using Docker and it becomes a prime choice among developers.
Hence the conclusion can be drawn that the Docker and virtual machines are not in conflict with each other, rather complementary to each other. Different workloads and usage is maintained by making the use of a hybrid of the two approaches by many organizations.The static part that doesn’t change often is maintained by the virtual machine part and the dynamic one that needs to be constantly updated by the Docker.