Docker containers are an innovative addition to the development of software applications. Big names back this technology in the IT field such as Microsoft, Google, IBM, and even Amazon. The average computer user has no idea about what a Docker container is, how it works, and how we can benefit from them. Let’s clarify these questions in this article.
What is a Docker Container?
If you are familiar with virtual machines, then the concept of containers should not be too difficult to understand. The major difference here, however, is that while virtual machines are run on top of the native (or host) operating system and use their own kernel, while containers share the same kernel with the host OS.
Docker is an open-source project that lets applications run inside of containers. Containers are virtual environments that have everything that a piece of software needs to run properly. This includes the code, libraries, runtime, and more.
While Docker has been bringing containers to the forefront, they are nothing new. Containers have been present on Linux, Unix, and Solaris for over a decade.
Advantages of Docker Containers over Virtual Machines
The main disadvantage of virtual machines is their resource requirements. Running an entire operating system and virtualizing the hardware that it needs takes a lot of computing power. On the other hand, a Docker container takes a lot fewer resources to run applications in their own fully contained environment. Sharing the operating system’s resources is much more efficient than running a virtual operating system on top of the host. This is ideal for companies that wish to cut back on a number of computing resources that their servers use, and is especially useful to cut back on the costs of scalable cloud hosting plans.
Another advantage that containers have over virtual machines is performance. Virtual machines take a long time to load compared to Docker containers since they must boot up, just like real hardware has to. Containers have shown performance on par with virtual machines, and in most cases, superior performance.
Containers also make things easier for developers. If a developer can get their application running in a container on a machine, then they can get it running on any system that uses the same operating system. Remember that all of the necessary libraries, code, runtimes, and so on are present within the container, so these components would not have to be installed directly onto the machine.
Disadvantages of Docker Containers
Docker containers seem far more efficient than virtual machines, but they are not without their disadvantages. The first disadvantage is flexibility. Virtual machines allow users to run different operating systems, while containers limit us to Linux operating systems, at least at the time of this writing. There is the solution of running both virtual machines and Docker containers in conjunction, however, and the project is still in development. Perhaps one day, containers will offer flexibility between operating systems. If an application requires a specific operating system to run it, a container just won’t cut it; a virtual machine will have to be employed.
Containers are also used to run single applications. If one wishes to run multiple applications, virtual machines are a better choice. When things get too complex and too many extra functions are added, the purpose of using containers is defeated. As a rule of thumb, use containers for running single applications and virtual machines for multiple applications.
Security is another big issue that containers have. While applications are contained within their own user spaces when using Docker, an application that has superuser privileges would also have the same privileges on the operating system. Obviously, this is a bad thing. While there are solutions to this security problem, they would take additional security checks, such as making sure that applications within containers are not given root access. This is not done by default, though, so it means additional manhours and tech-savvy will be required to have security when using containers.
While we are on the topic of security, malware is another issue that containers don’t handle as well as virtual machines. If a virtual machine is infected by a virus, for instance, the host operating system might not be infected. With containers, however, a virus has a greater chance of spreading since operating system resources, such as the file system, are shared.
Docker containers might not completely phase out virtual machines at the time of this writing, but they are an exciting technology that will continue to develop for the foreseeable future. The primary benefit of Docker containers is efficiency, making them great for firms with a limited number of servers, and those that want to reduce the consumption of computing resources. Security, however, is a factor that leaves much to be desired, keeping virtual machines live for the time being.