As the IT sector witnesses a boom, people who are working in the sector are determined to upskill themselves. They need to keep up with the creation, deployment, and running of applications easier. Below are the docker interview questions along with answers.
Docker makes such a simplification possiblenwith the help of containers. The containers let a developer package up an application with all the parts it needs. Then, they deploy all the parts as anpackage.
Docker is basically an open-source tool that uses the Linux Kernel features, such as control groups to create containers at the top of an operating engine. It has been developed by DotCloud. Docker is heavily dependent on cloud technology.
Knowledge of Docker is essential for those who are aspiring for a job in the IT sector. People who know how to use Docker get a lucrative salary. So, it is a good idea to know a few common questions recruiters ask the employees who are familiar with Docker.
Docker is an open-source lightweight containerization technology. It has gained widespread popularity in the cloud and application packaging world. It allows you to automate the deployment of applications in lightweight and portable containers.
Docker may be described as a containerization platform. It packages an application and all its dependencies together in the form of containers. The main aim of packaging everything in containers is to ensure that the application works seamlessly in any environment.
Basically, a Docker container wraps anything that may be installed in a server. It guarantees that the software will always work the same way, regardless of the environment in which it works.
The Docker Hub is the largest public repository of image containers in the world. It contains more than a million container images, sourced from individual developers, open-source projects, and commercial software vendors.
All the Docker Hub users may share their images at will. They may also download predefined base images that may be used as a starting point for any containerized project.
The Docker images create Docker containers. The registry in which the Docker images live is known as the Docker Hub, The users may pick up images from Docker Hub and use them to create customized containers.
Basically, Docker containers are runtime instances of Docker images. They are not restricted to any particular infrastructure. On the contrary, they run on any infrastructure and any cloud. The Docker containers share the kernel with other containers, running as isolated processes on the host operating system. They include an application and all its dependencies.
The Docker images are read-only files. On the other hand, Docker containers are live, executable content. It is possible for users to interact with the Docker containers.
A Docker image is the source of a Docker container. It is used to create containers. The moment a user runs a Docker image, an instance of a container is created. The Docker image might be deployed to any Docker environment.
A Docker Image contains executable application source code. It also contains libraries and tools that the application source code needs to run as a container. It is possible to create several Docker images from a single base image. All the Docker images will share the common features of their stock in that case.
Docker images are constituted of layers. Every layer corresponds to a version of the image. The moment a developer introduces any changes to a layer, a new top layer is created. This new top layer replaces the earlier top layer as the current version of the image.
Namespace adds a layer of isolation in containers. Docker provides different namespaces to stay portable and avoid affecting the underlying host system. A namespace is one of the most important features of Linux. User, Network and Mount are a few classic types of Namespace supported by Docker.
This is one of the most commonly asked questions during the interview. The life cycle of a Docker container is as follows-
Docker Machine may be described as a tool that allows the users to install Docker Engine on virtual hosts. Then, the hosts can be managed with the help of Docker-machine commands.
Docker Swarm is an important concept of Docker. It is a native clustering of Docker, that turns a pool of Docker hosts into a virtual and single Docker host. Any tool which already communicates with a Docker daemon may use Swarm to scale transparently to several hosts. It serves the standard Docker API.
Docker Compose is a YAML file. It contains details about the volumes, networks, and services for setting up the Docker application. So, people may use Docker Compose for creating separate containers and getting them to communicate with one another. It also hosts the different containers. Each container exposes a port for communicating with the other containers.
The reasons behind the popularity of Dockers are as follows-
Containers offer all the advantages of VMS, including cost-effective scalability, and application isolation. However, they also contain an additional level of abstraction at the OS level. As a result, it has the following advantages-
Docker is being used in the following areas-
Docker makes it easier for the developers to create ready-to-run containerized applications very fast. As a result, it simplifies the process of deploying and managing applications. The users are free to share containers with the applications.
The Docker containers are easy to deploy in any cloud platform. It may get more and more applications running on the same hardware as compared to any other technology.
Docker can be used in productions with Cloud platforms with the following positions-
It also runs on different Linux administration, like-
No, it is not possible for a container to restart by itself. The flag restart is set to false by default.
It is not possible to remove a paused container from Docker. The container needs to be in the stopped state before it is removed.
Platform providers like dotCloud and Heroku work on container technology. Containers may be scaled to thousands or even millions of them running in parallel.
Containers require memory and OS at all times. They also need a way to use this memory efficiently when scaled.
There are six possible states a container can be given at any point of time. They are as follows-
The stateful applications store data onto the local file system. The users need to decide to move the application to another machine when it becomes difficult to retrieve the data. So, many veteran Docker users claim that they do not prefer to run stateful applications in Docker.
Docker provides different functionalities like Docker events and Docker stats to monitor Docker in production. Docker events provide information about the activities that take place in the Docker daemon. On the other hand, Docker stats provide CPU and memory usage of the container.
It is necessary to introduce several changes to the Docker compose file before migrating the application to the production environment. The changes are as follows-
The most practical application of Docker compose is to use it in production. It is possible for users to use Docker compose in different stages of production like testing and staging.
When a Docker container exits, there is no chance of data loss. All the data written by the system gets preserved on the disk until the user deletes that particular container. The file system for the container continues even after the container stops or exits.
Docker architecture has four major components. They are as follows-
Let's understand each of the components-
A Docker file is a text document that contains all the commands a user may use to assemble an image.
Conclusion
Docker MAC is a desktop app for building, debugging and testing Dockerized apps on a Mac Docker desktop. Check the detailed docker training provided by Vinsys which is into training and certification courses from 20 years with the latest syllabus any by the industry experts trainers.
There is no setlist of Docker interview questions and their answers that will help the aspirants crack the interview. Only in-depth knowledge of Docker and hands-on experience in the relevant domain will help the candidates answer the questions smoothly.
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