DEVOPS INTERVIEW QUESTIONS

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DevOps Interview Questions
Q.1 What do you know about DevOps? A.1. DevOps is
a collaborative work culture, aimed to synergize
the efforts of the development and operations
teams to accelerate the delivery of software
products, with highest quality and minimal
errors. DevOps is about automation of the entire
SDLC with the help of automation tools to achieve
continuous development, continuous testing,
continuous integration, continuous deployment and
continuous monitoring. DevOps is re-org of the
existing resources where continuous improvement
is seeked through learning from constant
feedback. DevOps fulfils all the requirements for
fast and reliable development and deployment of a
software. Companies like Amazon and Google have
adopted DevOps and are launching thousands of
code deployments per day. Q.2. Why has DevOps
become so popular over the recent years? A.2. Let
us understand the impact of DevOps through some
examples Netflix and Facebook are investing in
DevOps to automate and accelerate application
deployment and this has helped them grow their
business tremendously. Facebooks continuous
deployment and code ownership models have helped
them scale up and ensure high quality experience
at the same time. Hundreds of lines of code are
implemented without affecting the quality,
stability, and security of the product. Netflix
is a streaming and on-demand video company which
also follows similar practices and has fully
automated processes and systems. Facebook today,
has 2 billion users while Netflix streams online
content to more than 100 millions users
worldwide. This is how DevOps has helped
organizations ensure higher success rates for
releases, reduce the lead time between bug fixes,
streamline and continuously deliver through
automation, and reduce their manpower costs. Q.3.
What is the difference between continuous
deployment and continuous delivery? A.3.
Continuous deployment is fully automated, and the
product deployment till production needs no
manual intervention whereas, in continuous
delivery, the deployment is done till QA or UAT
or pre-prod environment and further deployment
requires approval from the manager or higher
authorities to be deployed in production.
According to your organizations application risk
factor and policy, continuous deployment/delivery
approach will be chosen. Q.4. What is a version
control system?
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• A.4. Version control systems(VCS) consists of a
  central shared repository where teammates can
  commit changes and maintain a complete history of
  their work. It gives developers the flexibility
  to simultaneously work on a particular artifact
  and all modifications can be logically merged at
  a later stage.
• Version control allows you to
• Revert files back to a previous state.
• Revert the entire project back to a previous
  state.
• Compare changes over time.
• Track modifications done by developer with
  details.
• Does not allow overwriting on each other changes.
• Maintain the history of every version.
• There are two types of Version Control Systems
• Central Version Control System, Ex SVN
• Distributed/Decentralized Version Control System,
  Ex Git, Bitbucket
• Q.5. What is Git and explain the difference
  between Git and SVN?
• A.5. Git is a Distributed Version Control system
  (DVCS) which manages small as well as large
  projects efficiently. It is basically used to
  store our repositories in remote server such as
  GitHub.
• Its distributed architecture provides many
  advantages over other Version Control Systems
  (VCS) like SVN.
• GIT SVN

Git is a Decentralized Version Control Tool
SVN is a Centralized Version Control Tool
Git contains the local repo as well as the full
history of the whole project on all the
developers hard drive, so if there is a server
outage , you can easily recover code from local
git repo.
SVN relies only on the central server to store
all the versions of the project file
Push and pull operations are fast
Push and pull operations are slower compared to
Git
Client nodes can clone the entire repositories on
their local system
Version history is stored on server-side
repository
Commits can be done offline too
Commits can be done only online

• Q.6. What is CI? What is its purpose?
• A.6. Continuous Integration (CI) is a development
  practice that requires developers to integrate
  code into a shared repository, each time they
  make a commit.
• The CI process
• Developers check out code into their private
  workspaces.
• When they are done with it they commit the
  changes to the shared repository (Version Control
  Repository).
• The CI server monitors the repository and checks
  out changes when they occur.
• The CI server then pulls these changes and builds
  the system and also runs unit and integration
  tests.

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• The CI server will now inform the team about the
  successful build.
• If the build or tests fail, the CI server will
  alert the team.
• The team will try to fix the issue at the
  earliest opportunity.
• This process keeps on repeating.
• Hence, Continuous Integration as a practice
  forces the developer to integrate their changes
  every time so as to get an early feedback.
• Q.7. What is Jenkins? What are the advantages of
  Jenkins?
• A.7. Jenkins is an open source Continuous
  Integration tool which is written in Java
  language.
• It keeps a track on version control system and to
  initiate and monitor a build system if any
  changes occur. It monitors the whole CICD process
  and provides reports and notifications to alert
  the concern team.
• Advantage of using Jenkins
• Bug tracking is easy at an early stage in
  development environment.
• Provides support for many plugins to interface
  with various automation tools.
• Build failures are cached at integration stage.
• For each code commit change, an automatic build
  report notification get generated.
• To notify developers about build report success
  or failure, it can be integrated with LDAP mail
  server.
• Achieves continuous integration agile development
  and test-driven development environment.
• With simple steps, Maven release project can also
  be automated.
• Q.8. Why are configuration management processes
  and tools important?
• A.8. There are multiple software builds,
  releases, revisions, and versions for each
  software or
• testware that is being developed in a CICD
  pipeline. There is a need for storing and
  maintaining data, keeping track of development
  builds and simplified troubleshooting. CM tools
  let you achieve these objectives.

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Q.11. What is Ansible? A.11. Ansible is a
software configuration management tool to deploy
an application using ssh without any downtime.
Ansible is developed in Python language and is
mainly used in IT infrastructure to manage or
deploy applications to remote nodes. If we want
to deploy one application in 100s of nodes by
just executing one command, then Ansible is the
one agentless tool which provides you this
ability seamlessly. Q.12. What are playbooks in
Ansible? A.12. Playbooks are Ansibles
configuration, deployment, and orchestration
language. They can describe a policy you want
your remote systems to enforce, or a set of steps
in a general IT process. Playbooks are written in
a human-readable, easy to understand text
language. Q.13.What is a Docker container? How do
you create, start and stop containers? A.13.
Docker is a containerization technology that
packages your application and all its
dependencies together in the form of Containers
to ensure that your application works seamlessly
in any environment. A container consists of an
entire runtime environment an application, plus
all its dependencies, libraries and other
binaries, and configuration files needed to run
it, bundled into one package. Containerizing the
application platform and its dependencies
eliminates any infrastructure differences and
maintains consistency across environments. They
share the kernel with other containers, running
as isolated processes in user space, on the host
operating system. Docker containers can be
created by either creating a Docker image and
then running it or you can use Docker images that
are present on the Docker hub. We can use Docker
image to create Docker container by using the
below command docker run -t -i ltcommand
namegtlt/commandgt This command will create and
start container. Docker container can be run in
two modes Attached Where it will be run in the
foreground of the system you are running,
provides a terminal inside to container when -t
option is used with it, where every log will be
redirected to stdout screen. Detached This mode
is usually run in production, where the container
is detached as a background process and every
output inside the container will be redirected to
log files which can be viewed by docker logs
command. To check the list of all running
containers with status on a host docker ps -a
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• To stop the Docker container
• docker stop
• To restart the Docker container you can use
• docker restart
• Q.14. What is a Dockerfile used for?
• A.14. A Dockerfile is a text document that
  contains all the commands a user could call on
  the command line to assemble an image.
• Using docker build users can create an automated
  build that executes several command-line
  instructions in
• succession.
• Q.15. What is a Docker image?
• A.15. Docker image is the source of Docker
  container. Docker images are used to create
  containers. Images are created with the build
  command, and theyll produce a container when
  started with run. Images are stored in a Docker
  registry such as registry.hub.docker.com.
• Docker containers are basically runtime instances
  of Docker images.
• Q.16. What is Docker hub?
• A.16. Docker hub is a cloud-based registry
  service which allows you to use pre-defined
  images, build your images and test them, store
  manually pushed images, and provide a link to
  Docker cloud so that you can deploy images on
  your hosts.
• It provides a centralized resource for container
  image discovery, distribution and change
  management, user and team collaboration, and
  workflow automation throughout the development
  pipeline.
• Q.17. What are the advantages that
  Containerization provides over virtualization?
• A.17. These are the advantages of
  containerization over virtualization
• Containers provide real-time provisioning and
  scalability but VMs provide slow provisioning
• Containers have a minimal OS, and share the
  kernel of the underlying OS. VMs have the
  full-fledged OS
• Containers are lightweight when compared to VMs

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• Jenkins pulls this code from the repository using
  the Git plugin and build it using tools like Ant
  or Maven.
• Unit testing is performed using JUnit kind of
  framework. (JUnit plugin available in Jenkins).
• Once, the application is packaged in an
  executable file, it is pushed to an artifactory
  like JFrog and then, a Docker image comprising of
  the application (pulled from artifactory) and all
  its dependencies is created.
• Configuration management tools like Ansible
  deploy this image across environments with the
  environment specific
• configuration settings.
• Once it reaches testing environment, Selenium is
  used to run the automated test cases.
• Then, the image is deployed in pre-prod or
  staging environment by Ansible, and integration
  testing is done.
• Once the code is thoroughly tested in each of
  these environments, Jenkins send it for
  deployment on the production server (even
  production server is provisioned maintained by
  tools like Ansible).
• After deployment, continuous monitoring is done
  by tools like Nagios and logs are maintained and
  interpreted by tools like Splunk (log
  aggregator).
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