Devops Interview Questions and Answers

• DevOps promotes communication and collaboration between business, development & operations teams. In a way, we are talking about unification.
• DevOps is not only about tools but also about involving people and process.
• DevOps is inspired by the Agile process.
• DevOps is about automating the development, release and operation processes.
• DevOps helps in the speed of delivering applications to the end users.
• DevOps is also about continuous improvement which helps in learning through feedback.

To fulfil the need of delivering more and faster and better application to meet more and more demands of users, we need DevOps. DevOps helps deployment to happen really fast compared to any other traditional tools.

The most popular DevOps tools are mentioned below:

• Git : Version Control System tool
• Jenkins : Continuous Integration tool
• Selenium : Continuous Testing tool
• Puppet : Chef, Ansible : Configuration Management and Deployment tools
• Nagios : Continuous Monitoring tool
• Docker : Containerization tool

• Continuous Integration

• Continuous Testing

• Continuous Delivery

• Continuous Monitoring

Technical benefits:

• Continuous software delivery.
• Less complex problems to fix.
• Faster bug resolution.

Business benefits:

• Faster delivery of features for customer satisfaction.
• More stable operating environments.
• More time available to add product value.

• AWS is a cloud-based service provided by Amazon that ensures scalability through unlimited computing power and storage.

• AWS empowers IT enterprises to develop and deliver sophisticated products. It helps to deploy applications on the cloud.

• Some of its key services include Amazon CloudFront, Amazon SimpleDB, Amazon Relational Database Service, and Amazon Elastic Computer Cloud.

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.

Docker image is the source of Docker container. Or in other words, Docker images are used to create containers.

Docker Container is the running instance of Docker Image.

• We used to write commands onto script files and test them in a separate environment before deployment and this approach is being replaced by IaC now.

• Similar to the codes written for other services, with the help of AWS, IaC allows developers to write, test, and maintain infrastructure entities in a descriptive manner, using formats such as JSON or YAML. This enables easier development and faster deployment of infrastructure changes.

• The chef is considered to be one of the preferred industry-wide CM tools. Facebook migrated its infrastructure and backend IT to the Chef platform, for example. Chef helps you to avoid delays by automating processes. The scripts are written in Ruby.

• It can integrate with cloud-based platforms and configure new systems. It provides many libraries for infrastructure development that can later be deployed within a software. Thanks to its centralized management system, one Chef server is enough to be used as the center for deploying various policies.

Three most common DevOps KPIs are:

• Mean time to failure recovery
• Deployment frequency
• Percentage of failed deployments

Continuous Integration is a very important component of the Agile process. Typically developers work on features or user stories within a sprint and commit their changes to the version control repository.

Once the code is committed, then the entire work of developers is well integrated and the build is performed on a regular basis based on every check-in or schedule. Hence, Continuous Integration as a practice forces the developer to integrate their changes with others so as to get an early feedback.

• Continuous Delivery is an extension of Continuous Integration which primarily helps to get the features which the developers are developing out to the end users as soon as possible.

• During this process, it goes through various stages of QA, Staging etc., and then for delivery to the PRODUCTION system.

The main aim of Continuous Integration is to get the application out to end users that primarily enables continuous delivery. This cannot be completed without a sufficient amount of unit testing and automation testing.

Hence, we need to validate that the code produced and integrated with all the developers who perform as required.

As the application is developed and deployed, we do need to monitor its performance. Monitoring is also very important as it might help to uncover the defects which might not have been detected earlier.

Your working experience provide much more prompt answers for this question. I will share the primary benefits here.

Technical benefits:

• Continuous software delivery.
• Less complex problems to fix.
• Faster resolution of problems.

Business benefits:

• Faster delivery of features.
• More stable operating environments.
• More time available to add value (rather than fix/maintain).

• DevOps Architect – The leader who is responsible for the entire DevOps process.

• DevOps Engineer – The person should be experienced with Agile, SCM or Version Control, CI/CD and setting up automation tools for the same, Infrastructure automation and Database management skills. Any developer who has skills in coding or scripting and has the acumen to get into deployment or system admin can qualify for the role of a DevOps engineer.

Examples of popular Cloud Computing Platforms:

1. AWS – Amazon Web Services
2. Microsoft Azure
3. Google Cloud

The core operations of DevOps are application development, version control, unit testing, deployment with infrastructure, monitoring, configuration, and orchestration.

HTTP or Hypertext Transfer Protocol works in a client–server model like the most other protocols. HTTP provides a way to interact with web resources by transmitting hypertext messages between clients and servers.

• It is useful to track and maintain multiple software builds, releases, revisions, and versions for each software or testware that is being developed.

• And it’s an essential need to store and maintain data, keep track of development builds and simplified troubleshooting.

• The Key CM tools include Puppet, Ansible, and Chef help in automating software deployment and configuration on several servers.

• Data Redundancy and Replication

• High Availability

• Only one. git directory per repository

• Superior Disk Utilization and network performance

• Collaboration Friendly

• Git can use any sort of projects.

A kernel is the lowest level of easily replaceable software that interfaces with the hardware in your computer.

• The command ‘git pull’ pulls any new commits from a branch from the central repository and then updates the target branch in the local repository.

• But, ‘git fetch’ is a slightly different form of ‘git pull’. Unlike ‘git pull’, it pulls all new commits from the desired branch and then stores them in a new branch in the local repository.

• In order to reflect these changes in your target branch, ‘git fetch’ must be followed with a ‘git merge’. The target branch will only be updated after merging with the fetched branch (where we performed ‘git fetch’).

To be involved in the end to end delivery process and the most important aspect of helping to improve the process so as to enable the development and operations teams to work together and understand each other’s point of view.

It helps improve the collaborative work culture: Here, team members are allowed to work freely on any file at any time. The version control system allows us to merge all changes into a common version.

It keeps different versions of code files secure: All the previous versions and variants of code files are neatly packed up inside the version control system.

It understands what happened: Every time we save a new version of our project, the version control system asks us to provide a short description of what was changed. More than that it allows us to see what changes were made in the file’s content, as well as who has made those changes.

It keeps backup: A distributed version control system like Git allows all team members to have the complete history of the project file so that in case there is a breakdown in the central server, they can use any of their teammate’s local Git repository.

This feature is generally used to give the swap space to the server. Lets say in below machine I have to create swap space of 1GB then,

• dd if=/dev/zero of=/swapfile1 bs=1G count=1

• 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.

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)
• Mean time in between failures
• Change in failure rate
• Efficiency
• Pipeline Adoption
• Performance

Navigate to the “Manage Jenkins” and then “Global Tool Configurations” there you have to provide all the details such as Git URL , Java version, Maven version , Path etc.

Please check the items listed below.

• Check Network connection.

• Check whether the Web Server is receiving users’s request or not.

• Check the logs.

• Check the process id’s whether services are running or not.

• Check the Application Server is receiving user’s request or not.

One of the core advantages of DevOps automation is that it manages the role of human error out of the CD equation.

• Trunk based development signifies a source control branching model to organize software development.

• In this procedure, developers are engaged in code under a single branch and utilises document techniques in order to create long-lived development execution.

• Trunk based development is a key enabler for a number of integrations.

Jenkins Pipeline (or simply “Pipeline”) is a suite of plugins which supports implementing and integrating continuous delivery pipelines into Jenkins.

• To stop the container: docker stop container ID

• Now to restart the Docker container: docker restart container ID

Use following command and enter the required message. 

• Git commit –amend <your message>

Copy JENKINS_HOME directory and “jobs” directory to replicate it in another server.

Amazon provides the service called Amazon Elastic Container Service(ECS); By using this, we can create and configure the task definition and services to launch the applications.

Yes, we can do. I have listed one below. 

• We can copy the Jenkins jobs from one server to other server by copying the corresponding jobs folder. 

• Scrum is basically used to divide your complex software and product development task into smaller chunks, using iterations and incremental practises.

• Each iteration is of two weeks. Scrum consists of three roles: Product owner, scrum master and Team

git branch –merged

• The above command lists the branches that have been merged into the current branch.

git branch –no-merged

• This command lists the branches that have not been merged.

• Both ‘git rebase’ and ‘git merge’ commands are designed to integrate changes from one branch into another branch but in different approaches.

• When we perform rebase of a feature branch onto the master branch, we move the base of the feature branch to the master branch’s ending point.

• By performing merge, we take the contents of the feature branch and integrate them with the master branch. As a result, only the master branch is changed, but the feature branch history remains the same. Merging adds a new commit to your history.

• Rebasing will create inconsistent repositories. For individuals, rebasing makes a lot of sense. Now, in order to see the history completely, the same way as it has happened, we should use merge. Merge preserves history, whereas rebase rewrites it.

• Default file permissions are : rw-r—r—

• To change the default file permissions, we need to use umask command. ex: umask 666.

• Check out a set of source code files.

• Compile the code and report on progress along the way.

• Run automated unit tests against successful compiles.

• Create an installer.

• Publish the installer to a download site, and notify teams that the installer is available.

• Run the installer to create an installed executable.

• Run automated tests against the executable.

• Report the results of the tests.

• Launch a subordinate project to update standard libraries.

• Promote executables and other files to QA for further testing.

• Deploy finished releases to production environments, such as Web servers or CD manufacturing.

Above process will be done by Jenkins by creating the jobs.

• It supports only web-based applications.

• It does not support the Bitmap comparison.

• No vendor support is available for Selenium compared to commercial tools like HP UFT.

• As there is no object repository concept, maintainability of objects becomes very complex.

Please follow the steps listed below.

• Preparation & Planning : What kind of system/technology was supposed to run on what kind of machine
• Another important thing is the specifications regarding the clustering of systems.
• How do we integrate all these stand-alone boxes in a foolproof manner.
• Production setup should be documented to bits. It needs to be neat, foolproof, and understandable.
• It should have all a system configurations, IP addresses, system specifications & installation instructions.
• It needs to be updated as & when any change is made to the production environment of the system.

Multifactor authentication (MFA) is a security system that requires more than one method of authentication from independent categories of credentials to verify the user’s identity for a login or other transaction. 

• Security for every enterprise user — end & privileged users, internal and external.

• Protect across enterprise resources — cloud & on-prem apps, VPNs, endpoints, servers, privilege elevation and more.

•  Reduce cost & complexity with an integrated identity platform.