Docker containers are popular among machine learners and are considered as the new era and concept for virtualization. Virtual Machines are replaced by the Docker Containers. So, if you are also going to make your career as a Docker professional then here today we have brought some of the interview questions for Docker aspirants. The questions are suitable for experienced and fresh both candidates. The post will help you in getting an idea of the containers and in facing the interview and you can read the answers to get familiar with the technology.

Docker Interview Questions

  • What do you understand by Dockers? OR what is Docker?
  • Explain the Docker image.
  • Explain the Docker container.
  • Explain the Docker hub.
  • Explain the Docker Swarm.
  • Why Dockerfile is used for?
  • Give any use case where you have used Docker in your past projects.
  • How you can create the Docker container?
  • Explain Docker use case.
  • How hypervisors and containers are different as per virtualization. What are the benefits of both?

Docker Interview Questions and Answers

Q1). What do you understand by Dockers? OR what is Docker?

Docker is a containerization platform that helps the development team. The application can be packaged and delivered all at once. Here the packages and dependencies can be packed in the containers to make sure that the application will work independently in a seamless environment. It can be suitable for development, test and production environment.

Now you can define and describe the containers as the answer to this question:

The containers of Docker pack every part of the application that may be system tools, runtime, code, system libraries and other types of files. Here all types of files may be included that can be installed on the server, this way the developers can guarantee that the application will run on all the platforms regardless of the platform and environment.

The Docker containers usually run on the single machine that may have a sharing operating system, here the apps start only as the kernel uses less RAM and is run automatically.

Q2). Explain the Docker image.

Docker flow is nothing new, just the Docker container source. The images are used to create containers and are usually generated by the build command. The container is then produced when they are started with the b-run command. Docker registry contains the images like as these images are quite large. The Docker images are composed of other image layers. In these containers when the image is being transferred over the network then the minimal amount of data is also being sent.

Q3). Explain the Docker container.

This is one of the basic and most asked questions at the time of Docker’s interview. You should give a proper answer to this question when being asked. The specific answer is given below:

Docker containers have all the dependencies and application. In these containers, the kernel is being shared with several other containers. The container itself run as an isolated process at the user’s machine or system of the host operating system. Docker containers are not bound and dependent on any specific infrastructure. These containers can run on any system in any environment and in any cloud.

The containers can be created by using any machine through Docker image. Docker containers are also a run-time image of Docker containers.

Q4). Explain the Docker hub.

Docker hub is the cloud-based registry service and it allows the user to build his own images, to test the images, link them to the code repositories and link them to the Docker’s cloud so that the images can be deployed to the hosts. Docker’s hub is a centralized resource for image distribution, discovery, user and team collaboration, workflow automation and distribution and change management.

Q5). Explain the Docker Swarm.

Docker swarm refers to the native Docker clustering. A pool of Docker hosts when converted to a hub or virtual Docker host then it is known as Docker Swarm. Docker Swarm is a standard Docker API. Here the tool that communicates with the Docker daemon can use Swarm to transparently scale to the multiple hosts. Here some other supported tools are listed below:

  • Dokku
  • Jenkins
  • Docker Machine
  • Docker Compose 

Q6). Why Dockerfile is used for?

Docker images can be automatically built by using the Dockerfile instructions. Here, you can give a small definition of Docker files.

A Docker file is basically a text document that has all the commands. The user can use all the commands to form an image of the Dockerfile. Docker build can be used automatically to run several Docker commands and to build the Docker file image.

Q7). Give any use case where you have used Docker in your past projects.

You can here explain how you have used Docker in rapid development and deployment. You can also explain how you have used Docker with other tools like Chef, Jenkins, Puppet, and others. In case, if you have no experience of Docker’s tool and have experience with other similar tools then you can explain that too. You can compare Docker with those tools as well.

Q8). How you can create the Docker container?

Docker containers can be created by the Docker’s image and for this purpose, you can use the following command:

docker run –t -i command name

With the help of this command, you can create and start a container. The status of all the running containers can also be checked and for this purpose, you can use the following command:

dockerps -a

Q9). Explain Docker use case.

Docker is helpful in development environments. The apps can be deployed and re-deployed in testing environments. You can also use Docker in production. If you have any Node.js application that has some services then you will need full OS to run this application. Eligibility and benefit of Docker can be checked with the help of application for which you are creating the Docker. For some applications, it may be sufficient to create the Docker while for others it may be not.

Q10). How hypervisors and containers are different as per virtualization. What are the benefits of both?

If you want to run any application in a virtual environment like vSphere, then you will have to create the virtual machine first then install the OS and deploy the applications. In case of Docker, if you want to run the application then it is necessary to deploy it on Docker without any additional OS layer. The application can be deployed with its dependent libraries and rest, environmental support is provided by the kernel itself.

Final Words

Here, we have enlisted and included a few of the usually asked Docker interview questions but they are not limited, you can also find many other questions and for that, you must know the basics of Docker. It is a popular deployment tool that is common among developers. It is a complete and simple platform with the help of which developers can deploy their applications in any environment.