Docker

Question 1

What is Container?

Answer 1

Containers are a form of operating system virtualization. A single container might be used to run anything from a small microservice or software process to a larger application. Inside a container are all the necessary executables, binary code, libraries, and configuration files.

Question 2

Why we need container?

Answer 2

Containers require less system resources than traditional or hardware virtual machine environments because they don’t include operating system images. Applications running in containers can be deployed easily to multiple different operating systems and hardware platforms.

Question 3

What is difference between containerization and virtualization?

Answer 3

The cloud is a multi-tenant environment where multiple people run services on the same server hardware. To achieve a shared environment, cloud providers use virtualization technology.
Virtualization is achieved using a hypervisor, which splits CPU, RAM, and storage resources between multiple virtual machines (VMs). Each user on the hypervisor gets their own operating system environment.
Containerization is a form of virtualization. Virtualization aims to run multiple OS instances on a single server, whereas containerization runs a single OS instance, with multiple user spaces to isolate processes from one another. This means containerization makes sense for one AWS cloud user that plans to run multiple processes simultaneously.

Question 4

What is difference between a monolithic and microservice?

Answer 4

A monolithic application is built as a single unified unit while a microservices architecture is a collection of smaller, independently deployable services.

Question 5

Command to get Docker version?

Answer 5

docker –version

Question 6

Command to get information about a container?

Answer 6

docker inspect <container_name></container_name>

Question 7

How to pull Docker image?

Answer 7

docker pull <name_image></name_image>

Question 8

Command to check images available in local Docker engine?

Answer 8

docker images

Question 9

How to remove image?

Answer 9

docker rmi <name_images></name_images>

Question 10

What are modes to spin a container?

Answer 10

Interactive and detached

Question 11

Command to spin up a in detached mode container?

Answer 11

docker run -d name of the container

Question 12

Command to spin up a in interactive mode container?

Answer 12

docker run - -it nginx

Question 13

How to spin up a container by name?

Answer 13

docker run –it - -name mayo_ubuntu ubuntu

Question 14

Command to check the running containers?

Answer 14

docker ps

Question 15

Command to check all the containers available?

Answer 15

docker ps -a

Question 16

How to start a container?

Answer 16

docker start <name_container></name_container>

Question 17

How to stop a container?

Answer 17

docker stop <name_container></name_container>

Question 18

How to remove a container?

Answer 18

docker rm <container_name></container_name>

Question 19

How to get more detailed information about a container?

Answer 19

docker inspect <container_name></container_name>

Question 20

How to list docker networks?

Answer 20

docker network ls

Question 21

How to create a docker network?

Answer 21

docker network create - -driver bridge <network_name></network_name>

Question 22

What to map a port with the local port of a container?

Answer 22

–p
docker run -d –name web -p 8080:nginx

Question 23

Who is responsible for the mapping of container port?

Answer 23

docker proxy

Question 24

What is your experience with Docker. Please give me brief idea of your background with containers?

Answer 24

Containers are lightweight and portable, and they allow developers to isolate applications from one another and from the underlying host operating system. This makes it easier to deploy and run multiple applications on the same machine without them interfering with each other.

Question 25

Difference between Docker Container and Docker Image?

Answer 25

Images can exist without containers, whereas a container needs to run an image to exist.
Docker image is a read-only immutable template that defines how a container will be realized.
A Docker container is a runtime instance of a Docker image that gets created when the $ docker run command is implemented.A text document that contains all the commands to build an image

Question 26

What is a docker file?

Answer 26

A text document that contains all the commands to build an image

Question 27

How to build a customized Docker image?

Answer 27

To build a customized Docker image, you will need to create a Dockerfile. A Dockerfile is a text file that contains instructions for building a Docker image.

Question 28

How to build docker image from running container?

Answer 28

you can use the docker commit command. The docker commit command creates a new image based on the changes made to a container.
docker commit -m “Centos1” –author marjorie cont1 new_cont

Question 29

What is Docker volume?

Answer 29

Docker volumes are file systems mounted on Docker containers to preserve data generated by the running container. The data doesn’t persist when that container no longer exists, and it can be difficult to get the data out of the container if another process needs it.

Question 30

Why we need Docker volume?

Answer 30

The purpose of using Docker volumes is to persist data outside the container so it can be backed up or shared. Docker volumes are dependent on Docker’s file system and are the preferred method of persisting data for Docker containers and services.

Question 31

What flag you use to create and attach a Docker volume with your container?

Answer 31

you can use the -v or –volume flag when running the docker run command.
docker run -d -v voume_mayo:/tmp - -name mayo_ubuntu ubuntu

Question 32

What is Docker compose?

Answer 32

Docker Compose is a tool that assists in defining and sharing multi-container applications. By using Compose, we can define the services in a YAML file, as well as spin them up and tear them down with one single command.

Question 33

What is Docker registry?

Answer 33

A Docker registry is a storage and distribution system for named Docker images
Docker Hub.
Azure Container Registry.
Google Container Registry.
Google Artifact Registry.
Amazon EC2 Container Registry.
Bintray.io/Artifactory.
Quay.io.
Github Container Registry.

Question 34

What feature of the Linux Kernel does docker use in the backend?

Answer 35

OverlayFS is a union file system for the Linux kernel that allows multiple lower file systems to be “overlaid” on top of each other, with the upper file system taking precedence. This means that changes made to files in the upper file system will take precedence over the same files in the lower file systems.Docker uses OverlayFS as its default storage driver to manage container images and layers. Each time a container is run, a new layer is created on top of the image, and any changes made to the container are stored in this new layer. The uppermost layer contains the changes made to the container, while the lower layers contain the original image. This allows for efficient storage and management of container images, as multiple containers can share the same underlying image layers while still having their own unique changes.