Docker Interview Questions

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.

Here, are a major advantage of using Docker.

• Offers an efficient and easy initial set up
• Allows you to describe your application lifecycle in detail
• Simple configuration and interacts with Docker Compose.
• Documentation provides every bit of information.

Here are the essential features of Docker:

• Easy Modeling
• Version control
• Placement/Affinity
• Application Agility
• Developer Productivity
• Operational Efficiencies

Some notable drawbacks of Docker are:

• Doesnt provide a storage option
• Offer a poor monitoring option.
• No automatic rescheduling of inactive Nodes
• Complicated automatic horizontal scaling set up

The Docker image help to create Docker containers. You can create the Docker image with the build command. Due to this, it creates a container that starts when it begins to run. Every docker images are stored in the Docker registry.

Docker daemon or Docker engine represents the server. The docker daemon and the clients should be run on the same or remote host, which can communicate through command-line client binary and full RESTful API.

Dockers public registry is called Docker hub, which allows you to store images privately. In Docker hub, you can store millions of images.

$ docker ps

$ sudo docker stop container name

$ sudo docker run -i -t alpine /bin/bash

The common instruction in Dockerfile are: FROM, LABEL, RUN, and CMD.

Memory-swap is a modified flag that only has meaning if- memory is also set. Swap allows the container to write express memory requirements to disk when the container has exhausted all the RAM which is available to it.

Docker Swarm is native gathering for docker which helps you to a group of Docker hosts into a single and virtual docker host. It offers the standard docker application program interface.

Docker states and Docker Events are used to monitoring docker in the production environment.

Important states of Docker container are:

• Running
• Paused
• Restarting
• Exited

Docker hub is a cloud-based registry that which helps you to link to code repositories. It allows you to build, test, store your image in Docker cloud. You can also deploy the image to your host with the help of Docker hub.

Docker object labels is a method for applying metadata to docker objects including, images, containers, volumes, network, swam nodes, and services.

FROM pyhton:2.7-slim

WORKDIR /app

COPY . /app

docker build –tag

You need to navigate:

/var/lib/docker/volumes

You can communicate between Docker client and Docker Daemon with the combination of Rest API, socket.IO, and TCP.

You need to do the following things:

• Runs Jenkins on docker
• You can run integration tests in Jenkins using docker-compose

In docker file, we need to use COPY or ADD directive. This is useful to relocate code. However, we should use a volume if we want to make changes.

The Docker containers can be scaled to any level starting from a few hundred to even thousands or millions of containers. The only condition for this is that the containers need the memory and the OS at all times, and there should not be a constraint when the Docker is getting scaled.

Below are the steps for Docker life cycle:

• Build
• Pull
• Run

CNM stands for Container Networking Model. It is a standard or specification from Docker, Inc. that forms the basis of container networking in a Docker environment. This dockers approach provides container networking with support for multiple network drivers.

Yes, Docker provides support IPv6. IPv6 networking is supported only on Docker daemons runs on Linux hosts. However, if you want to enable IPv6 support in the Docker daemon, you need to modify /etc/docker/daemon.json and set the ipv6 key to true.

No, any data that your application writes to disk get stored in container. The file system for the contain persists even after the container halts.

Bind mounts- It can be stored anywhere on the host system

To configure the Docker daemon to default to a specific logging driver. You need to set the value of log-driver to the name of the logging drive the daemon.jason.fie.