Docker Interview Questions For Freshers & Experienced

Docker Interview Questions

This is a brief introduction to Docker. To know more, read online interview questions of Docker and update yourself with the basic concepts. Also, you will come to know about the pros and cons of Docker that will help you in deciding to choose Docker or not for your application. In this article, you come to know about the basics of Docker, its pros and cons.

Docker vs Jenkins. Which is better?

Advantages of Docker:

• Simplicity and Flexibility: The key benefit of Docker is its simplicity and flexibility. It simplifies the matters and allows the users to take their configurations. It is enough flexible to let users use their configurations in the code and moreover, to deploy it too. Along with that, there is no problem with the environment, as Docker can be used in various types of environments.
• Lightweight Virtualization: Docker helps to reduce the overhead, as in it no guest Operating system is required to boot. Therefore, this makes the Docker faster than the Virtual Machine. Many containers have their processes, network, users and systems but they share the kernel of host operating system. When we run the Docker container, then the host operating system assumes that it is the start of another process. This is how the speed of the container is increased. 
• Integration: When it comes to Integration, Docker is not behind. Instead, it works very well with a few efforts by using its tools such as Travis, Wercker, etc. These tools store the newer version as a Docker image, and whenever source code is updated, you just need to tag it with a version number. After that, push it to Docker Hub and then deploy it to the production.
• Environment Maintenance: As manually maintaining an environment is error-prone and can be a nightmare. With docker, the creation of an environment is automated, hence, very few actions are required by the developer. We just have to run the image on the servers to create instances of an environment. This increases the reliability which in turn decrease the risks. 
• Security: Security is the key feature for every application as every user wants it. So, Docker also provides security by isolating the applications from each other. It ensures that the applications running on containers are fully segregated and grants us complete control over traffic flow. 
• Docker file: To set up an environment, we use the “infrastructure-as-code" approach. The environment is described in the Dockerfile in our documentation. We can track the changes applied to the environment by putting the Dockerfile under version control. This way, we always have reliable documentation of our infrastructure. Moreover, we have to change the documentation to change the environment, thus always have up-to-date documentation.

Disadvantages of Docker:

• Data Storage in a container: Docker shows a big problem whenever the container shuts down. At that time, all the data in the container disappear forever if you haven't stored the data somewhere else.  Therefore, we need backup strategies, but they are still in progress or not very scalable yet.
• Bug in Kernel: Since the containers share the same kernel, therefore the bug in the kernel will affect every container.  Although the containers are isolated to each other but not as much as real VMs.
• Cross-platform Compatibility: Docker doesn't support cross-platform compatibility. This means an application designed in Docker container to run on windows, can’t run on Linux and vice versa. Therefore, this drawback makes the Docker less popular where environments are composed of both windows and Linux servers.
• Not good for graphical applications: Docker was designed to run the applications that are not based on a graphical interface. But nowadays, nearly all applications based on GUI. So, to run these applications in a container, you have to use creative strategies that are clumsy.