Docker Interview Questions

Introduction

In the digital age, the importance of software development is immense. Organizations from across the world have been building custom software applications to leverage their processes and attain their inherent objectives. It is platforms like Docker that enhance software development projects and help developers build robust software. Docker is an open-source containerization platform that helps users build deploy, and run powerful applications. It lets you decouple your software from its underlying infrastructure. To understand Docker and prepare for Docker questions, it is important to know what a container is. In the world of software development, a container refers to a standard unit of software that is bundled with dependencies to ensure fast and secure deployment of applications between different computing systems. Simply put, Docker can be considered a large ship carrying multiple boxes of cargo (containers). The demand for Docker professionals keeps increasing as organizations embrace digitization. If you wish to land a Docker job, make sure you prepare well for your interviews. Here, recruiters will test your practical and theoretical knowledge of Docker to gauge your expertise. Here are a few important Docker interview questions and answers that will help you prepare for the big day!

Docker Interview Questions For Freshers

Let us start by answering a few Docker interview questions suitable for beginners with little to no work experience:

A Docker container is a component that contains applications and their dependencies. Containers share kernel and system resources with multiple containers while running as isolated systems within the host operating system. The primary purpose of a Docker container is to steer away from infrastructural dependency while ensuring seamless deployment and running of software applications. This can be a direct interview question or appear as a Docker MCQ if your recruiter asks you to give a written test before/during an interview.

Docker images are executable packages that are bundled with app code, dependencies, software packages, and more. Their primary purpose is to create containers. Developers can deploy Docker images to any Docker environment and spin the containers up there to run the concerned application.

Docker Compose is a YAML file that contains details regarding multiple networks, services, and volumes needed to set up a Docker-based application. It is used to create and host multiple containers, along with establishing seamless communication between them.

Docker namespace refers to a Linux feature that ensures the partition of OS resources in a mutually exclusive way. It introduces a layer of isolation amongst Docket containers. Namespaces also ensure that the containers are portable and have no impact on the underlying host. Mount, PID, User, Network, and IPC are some common examples of Docker namespaces.

The data stored in a Docker container remains intact unless you delete the container on purpose.

Advanced Docker Interview Questions

Let us now have a look at the Docker interview questions for experienced professionals:

There is no well-defined limit to the number of containers you can run in Docker. It all depends on the hardware restrictions that limit the number. Two major factors limiting this number are the application size and CPU resources. If you have enough CPU resources and your application is not too big, you can run several containers in Docker.

Here are the different stages in the lifecycle of a Docker container:

Created - This is the stage where a container is created but not started
Running - This is the phase where a Docker container runs with its associated processes
Paused - At this stage, the running container is paused
Stopped - This is the stage when a Docker container is finally stopped
Deleted - This is when a container is removed from the system

The Docker Compose feature will help you use Docker for multiple application environments. You can define several networks, services, and containers in a Docker Compose file along with clean volume mapping. If multiple application environments are concerned, you can define the server-specific processes and dependencies to run your application.

The Docker info command is used to obtain detailed information about the Docker installed in your host system. This information can be about anything, from the number of images or containers to the state they are running in and hardware specifications.

In Docker Compose, the Up command allows you to keep the Docker Compose up at all times. It lets you start or restart the services, networks, and drivers associated with your application as specified in the docker-compose.yml file. If you are running Docker Compose in the “attached” mode, all container logs will become accessible to you. If you run it in the “detached” mode, the Docker Compose will exit and show no logs after the containers are started. The Run command is used to run one-off tasks according to your business requirements. You need to provide a service name here and the docker will start only the service you mention. It will also run other services if the target service is dependent on them. The Start command is used to restart only those containers which have already been created and stopped. It is not useful in creating new containers in Docker.

The Final Word

These were some of the most common and important ReactJS interview questions and answers you should keep in mind if you are applying for a job as a ReactJS developer. Make sure you know the development framework like the back of the hand and are capable of applying the theoretical knowledge to solve your clients’ problems. Depending on the designation you are applying for and the experience you possess, prepare yourself in a way that the recruiters find value in bringing you on board!

Frequently Asked Questions

Why is it beneficial to learn Docker and secure a job in the domain?

If you want to get into the realm of application development, you will need to know components like Docker that play an important role behind the scenes. Learning Docker helps you accelerate application development and deploy software solutions in the best way possible. Along with accelerating the application workflow, learning Docker also helps you develop applications using your own technologies and environments.

What is the average salary of a DevOps Engineer with Docker skills in India?

The average starting salary of a DevOps Engineer with Docker skills in India is around ₹6.5 lacs. If you upskill yourself and climb up the corporate ladder with your expertise, you can ask for a package as big as ₹23 lacs per annum as a DevOps professional skilled in Docker.

Which major companies use Docker in their tech stacks?

Here are some of the major companies using Docker in their tech stacks:

Shopify
Pinterest
Twitter
Udemy
Robinhood
Robinhood
Delivery Hero
Spotify

Is learning Docker sustainable for my IT career?

Learning Docker not only enhances your skill set but also makes you eligible for better job opportunities as a DevOps Engineer. As long as organizations around the world will need skilled DevOps professionals to develop, deploy, and run their applications, your Docker skills will not go in vain. However, make sure you keep upgrading your skills and stay in tune with the current tech trends in the industry. This will help you build a strong, long, and illustrious IT career.

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Docker Interview Questions

Introduction