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The most significant tools in DEVOPS are-

• Git- version CONTROL system tool
• Jenkins- CONTINUOUS INTEGRATION tool
• Docker- containerization tool
• Puppet- configuration management and deployment tool
• Ansible- configuration management and deployment tool
• Nagios- continuous monitoring tool

The key COMPONENTS in DevOps essentially involve-

• Continuous integration
• Continuous delivery
• Entire microservices
• Infrastructure as a code
• Monitoring and logging
• Communication and collaboration

The majorly used key performance indicators (KPIs) in DEVOPS are-

• Deployment FREQUENCY and failure
• Change lead time
• Change in volume
• Mean time to detection
• Mean time to recovery (MTTR)
• Meantime in between failures
• Change in failure rate
• Efficiency
• Pipeline adoption
• Performance

The CORE OPERATIONS in DevOps for INFRASTRUCTURE are as follows-

• Provisioning
• Configuration
• Orchestration
• Deployment

• Code building
• Code coverage
• Unit testing
• Packaging
• Deployment

DevOps is ACTIVELY used in the organizations to maintain application delivery and close ALIGNMENT of services considering the business objectives. There are several reasons to adopt the technology OFFERED by DevOps, some of them are-

• It helps in faster innovations
• It also provides less DEVELOPMENTAL cycles
• It also reduces the deployment failures
• Improvisations in communication and collaboration
• It OFFERS a stable operating environment
• Significant increase inefficiencies
• Cost reduction along with the infrastructure and IT headcount

Version control system or VCS REFERS to software which is utilized by the DEVELOPERS to work simultaneously maintaining the history of their previous as well as current actions.

• It helps developers to work together.
• It does not permit OVERWRITING on changes.
• Maintains a complete history of earlier provisions and complete changes.

There are BASICALLY two types of version control systems found which are-

• A central version control system, its EXAMPLE is Git, Bitbucket
• A distributed or decentralized version control system, its example is SVN.

The basic component which is required for the PUPPET configuration management policy is known as Puppet Manifest. Each of the Puppet nodes or Agents has your configuration details in their native language provided in Puppet master. The details are provided BASED on how RESOURCES should be configured and their terms. It also declared the resources by defining the STATE which needs enforcement on any note. To develop complex Puppet MODULES, they are considered the major building blocks.

DevOps refers to the close association of development as WELL as operational tasks. It does not refer to a SET of tools or any SOFTWARE framework rather it is a combination of specialized tools that help in the automation of the entire INFRASTRUCTURE. It also refers to the implementation of Agile methodology on development as well as operational upfronts.

No, it is not possible to remove a paused container. Before it can be removed the container NEEDS to be in the stopped state.

This guide of BEST Docker questions and answers was presented to you by considering all the essentials regarding the same. This will help to increase the crackdown rate of a candidate.

By using and implementing Docker large number of functioning and applications are hosted which are-

• It enables the specification and isolation of applications.
• It promotes RAPID deployment in the FORM of virtualization at the various operating system level.
• Simplify configurations.
• It provides EASE with infrastructure level configuration.
• It actively manages the code pipeline offering consistent environment and stability.
• It lowers the utilization of various services in the form of containers.
• It improvises the productivity of developers by providing them concentrated logic.

In Docker, there can be as many containers DEFINED PER HOST because Docker does not restrict anyone of them. The only thing to be considered is that every CONTAINER requires the storage space, memory and CPU supporting the hardware as well. It is also advised to consider the size of application as containers are lightweight and extremely dependent upon the host operating system

Docker CONTAINERS are rapidly gaining popularity at the enterprise level and it is CERTAINLY becoming an essential part of several professional pipelines. Docker is one of the SUPREME and effective platforms for organizations that understand the consequences of CONTAINERIZATION.

Docker uses cache to enhance the speed of building the project and other instances. All the COMMANDS mentioned in the Docker file are used to build other Docker containers and its outcomes are separately stored in a layer. These layers are built on top of every other layer.

Docker runs the Docker file and MAKES an effort to EXECUTE steps one after the other before the finalization. DEVELOPING the Docker images with a Docker file is extremely faster as compared to the provision with ansible. This is possible because of the utilization of Docker cache and supreme based images.

The user required Docker-compose up UP is used to start or restart the services which are defined under Docker-compose.yml. In the default attached mode, all the logs from containers will be visible to you. In detached mode COMPOSED exits by STARTING the container but containers PURSUE running in the background.

The Docker-compose run command is utilized for ad hoc or one-off tasks. They also require the services name in which the user wants to UTILIZE run and only start the container for the same services which are dependent on the running services. It is also used to test or perform administrative tasks like REMOVING or adding data to the volume container.

The Docker-compose start command is used to restart the containers that were created earlier but stopped. With this command, new containers cannot be created.

At PRESENT doctor is actively available on the platforms mentioned below-

• Ubuntu 12.04, 13.04
• Fedora 19/20+
• CentOS 6+
• RHEL 6.5
• Gentoo
• ArchLinux
• OpenSUSE 12.3+
• CRUX 3.0

At present Docker is also available on the CLOUD environment and the platform it SUPPORTS are-

• Amazon EC 2
• Google COMPUTE engine
• Microsoft azure
• Rackspace

The Docker container can be CREATED from any specific Docker image of the user's preference and the same can be obtained using the COMMAND-

Docker run t - i command name

This command will help you CREATE the container and the same will start for you. To check the stability of the Docker container and if it is created or not, you can use the command mentioned below. This command will also check if it is running or not and it will list out all the containers along with their STATUS on the host system where the Docker container is running. Docker ps-a

The difference between Docker and the virtual machine is as follows-

Docker Swarm is a way of orchestrating the Docker containers where Dockers can be implemented in a cluster. To support the easy monitoring and Management Docker pools can be converted into an individual Docker Swarm.

Note: This is one of the essential Docker interview questions and answers.

A complete set of instructions that are used to pass on the Docker to HELP in the image build-up is known as DOCKERFILE. It can be also considered as a text document having all the necessary commands which are required for CREATING a Docker image. An automated build can also be CREATED which executes various command LINES one after the other.

On broad terms, Docker and hypervisor form the same WORKING but still, there is a wide range of differences between them. Docker is a lightweight technology as it RAISES fewer resources and also hosts kernel. Hypervisor technology creates the Colonel rather than hosting.

Most significant features of Docker from other competitive technologies are-

• The Docker container can be run on PC as well as the company's or Enterprise's IT system.
• As Docker is a repository of containers it can be DEPLOYED and downloaded on all the APPLICATIONS from a centralized location
• The applications can be shared actively with all the containers that were CREATED earlier.

The most important COMMANDS in Docker are-

• Docker- It is used to launch the Docker daemon
• Build- It is used to build IMAGE files in Docker
• Create- It is used to create a NEW container
• KILL- It is used to kill the container
• Commit- It is used to create a new image from the container modifications.

Docker objects: The Docker objects refer to the Docker images, containers and services. A Docker image is a read-only template having the configuration and runtime instructions for Docker instructions. Under the SERVICE instruction scaling of the containers across MULTIPLE Docker, daemons are ALLOWED. All this together WORKS as Swarm.

Docker namespaces: It refers to a technology that provides individual and isolated workspaces known as containers. Docker namespaces also provide a layer of isolation for containers.

It is justified in Docker that the CONTAINERS are made up of Docker images. These Docker images are DEFINED in a separate registry which is known as Docker Hub. From this defined registry it is easy for the users to pick images and use them to create containers and customized images. At present Docker Hub is the WORLD's largest PUBLIC repository for IMAGE containers.

The DOCKER architecture majorly CONSISTS of an engine which refers to a client-server application having three major components, these components are-

• A server which REPRESENTS the long-running program type known as a daemon process (Docker command)
• A REST API which defines the interface used in the program to TALK to the daemon and then follow the instructions
• A command-line interface client
• CLI utilizes the Docker REST API to organize or control Damon with scripting or direct commands.

VIRTUALIZATION is a PROCESS of creating the virtual session of computer STORAGE, service or applications which are software-based. This virtual environment is created from a single segment of the physical hardware system and through it, you can split one system into various other sections acting like a separate and distinguishable system. With the help of hypervisor, this splitting is EXECUTABLE and the virtual session created by this medium is KNOWN as a virtual machine.

A DOCKER image is the fundamental source of Docker CONTAINER it is better to say that they are used to create the Docker containers. When the user RUNS these images corresponding INSTANCE for the container is developed automatically in it. These images can be used for any other Docker ENVIRONMENT as well.

The application and its dependencies are included in Docker containers. It can also share the kernel with VARIOUS other containers running on individual PROCESSES in user SPACE on any of the host OPERATING systems. These containers are not BOUND to any defined specific infrastructure or any computer or infrastructure. They are compatible with the cloud and runtime instances of images.

The LIFECYCLE of a DOCKER is as follows-

• Create a CONTAINER
• Run the Docker container
• Pause container
• Unpause container
• Start container
• Stop container
• Restart container
• Kill container
• Destroy container

NOTE: As we are going through Docker interview questions and answers it is very important to have a brief over what is Docker.

Docker presents a containerization platform packaging applications along with its dependencies together in a container form. It is yours that the applications work seamlessly under any environment (no matter if it is a test, DEVELOPMENT of production). The Docker containers wrap the piece of software in an entire file system containing the essentials like code, runtime, system libraries, system tools and MANY more. It also wraps EVERYTHING which is installed on a SERVER guaranteeing its run time regardless of the environment.

Hypervisor refers to SOFTWARE which has a tendency to make virtualizations possible and it is also known as virtual machine MONITOR. The hypervisor also segments the host system by allocating the resources to the individual virtual environment. With this utility, the user can have various operating systems on a single host system.

• Type 1: It is known as a native hypervisor or bare-metal hypervisor which runs directly under the host system.
• Type 2: It UTILIZES the underlying host operating system it is also known as a HOSTED hypervisor.

To send an EMAIL in PYTHON, follow these STEPS along with the code:

import smtplib

sender = '[email PROTECTED]'
receivers = ['[email protected]']

message = """From: From Person <[email protected]>
To: To Person <[email protected]>
Subject: SMTP email test in Python

This is a test email message in Python.
"""

try:
   smtpObj = smtplib.SMTP('localhost')
   smtpObj.sendmail(sender, receivers, message)         
   print "Successfully sent the email"
except SMTPException:
   print "Error display: Python is unable to send an email"

To create a named tuple in Python, FOLLOW these steps:

• IMPORT the namedtuple class from the collections module.
• Now, the constructor shall take the name of the named tuple and a STRING CONTAINING the names of the field, SEPARATED by whitespace.
• The above action shall return a new namedtuple class for the specified fields.
• To use the new namedtuple, call the new class with all the values (in order) as parameters.

In Python, a shallow copy essentially means building a new collection of objects and then referencing it with the child objects found in the original group of the object.

Note: Did you know, Python is also referred to as a “batteries included” language DUE to its comprehensive STANDARD LIBRARY. Our Python Interview Questions have been selected from a plethora of queries to HELP you gain valuable insights and boost your CAREER as a Python Experts.

In Python, the DIR() function is used to return all the properties and methods within a specified object, without actually having the VALUES. The dir() function shall return all the features and methods present, INCLUDING the in-built properties, which are set as default for all the objects within.

Here’s a SHORT example to demonstrate the dir() function in Python:

class Person:
  name = "John"
  age = 36
  country = "Norway"

print(dir(Person))

Output

['__doc__', '__module__', 'age', 'country', 'name']

Debugging in Python can be done by UTILIZING the inbuilt module pdb. This module actually defines the interactive SOURCE CODE debugger for all the Python PROGRAMS.

Python easily SUPPORTS the FORMATTING for any value into a string which may contain a NUMBER of complex expressions. The utility includes pushing the VALUES with the help of % format specifier into a string.

There are TWO CATEGORIES of ‘TYPES’ present in PYTHON, which is mutable and immutable.

• List
• Dictionary
• Set

• String
• Number
• Tuple

It is a Python LIBRARY used to OPTIMIZE, define, and execute the MATHEMATICAL expressions including multidimensional arrays.

DeQue MODULE is a segment of the collection library that has a feature of addition and removal of the ELEMENTS from their respective ENDS.

The WAY of using the operating system dependent functionalities is an OS MODULE. Through this FUNCTION, the INTERFACE is provided with the underlying operating system for which PYTHON is running on.

• SELECT the URL you WANT to scrap
• Inspect the page
• Select data you want to extract
• Write the codes and run them

Once the data is EXTRACTED store the data in any REQUIRED format

In Python, an array of RANDOM integers can be GENERATED through the function randint () NumPy. This function usually starts with three arguments; from the lower end, the upper-end range and the NUMBER of ACTUAL integer values to successfully generate the SIZE of the array.

from random import SHUFFLE

X = ['My', 'Singh', 'Hello', 'India']

shuffle(x)

PRINT(x)

The OUTPUT of the following code is as below.

['Singh', 'India', 'Hello', 'My']

A thread is a lightweight PROCESS. Multithreading allows the programmer to execute multiple THREADS in one go. The Global Interpreter LOCK ensures that a SINGLE thread performs at a given time. A thread holds the GIL and does some work before passing it on to the next thread. This looks like PARALLEL execution, but actually, it is just threading taking turns at the CPU.

NOTE: The page you are accessing has some of the most basic and complex Python Interview Questions and Answers. You can download it as a PDF to read it later offline.

A Flask is a microframework build for small applications with more STRAIGHTFORWARD requirements. Flask comes READY to use.

Pyramids are built for larger applications. They provide flexibility and ALLOW the developer to use the right TOOLS for their projects. The developer is free to choose the database, templating style, URL STRUCTURE, and more. Pyramids is configurable.

Similar to Pyramids, Django can be used for larger applications. It includes an ORM.

For performing Static ANALYSIS, PyChecker is a tool that DETECTS the bugs in source code and warns the programmer about the style and complexity. Pylint is another tool that authenticates whether the module MEETS the CODING standard.

In total, there are 33 KEYWORDS in PYTHON. It is important to know them all in order to know about their use so we can UTILIZE them. In additon, while we are naming a VARIABLE, the name cannot be matched with the keywords. This is ANOTHER reason to know all the keywords.

The built-in METHOD which decides the types of the variable at the program runtime is known as type() in Python. When a single ARGUMENT is PASSED through it, then it returns given OBJECT type. When 3 ARGUMENTS pass through this, then it returns a new object type.

The entity that changes the data types from one form to another is KNOWN as typecasting. In programming languages, it is used to make sure the variables are processed in the correct sequence by the function.

E.g., while converting an integer to string.

The popularity of programming languages depends on their FUNCTIONALITIES, ease of learning, and usage. PYTHON is easy to learn, very efficient, and has a large DEV community. Here’s a list of Python Basic Interview Questions to help you start your journey as a Python Developer.

It refers to the METHOD which ADDS a certain value to the CLASS. It can’t be initiated by the user rather only occurs when an internal ACTION takes CHARGE. In python, the built-in classes define a number of magic methods.

Both lists and ARRAYS in Python can STORE the data in the same way.
The difference is-

This function returns to a PRINTABLE PRESENTATION for the GIVEN object. It takes a single object & its syntax is repr(OBJ). The function repr computes all the FORMAL string representation for the given object in Python.