DevOps Interview Questions and Answers

1. What is DevOps?

DevOps is a set of practices that combines software development (Dev) and IT operations (Ops) to shorten the systems development life cycle and provide continuous delivery with high software quality.

2. Explain the concept of Continuous Integration (CI).

Continuous Integration is the practice of automatically integrating code changes from multiple contributors into a shared repository multiple times a day. It involves building and testing the code automatically.

3. Why DevOps has become famous?

These days, the market window of products has reduced drastically. We see new products almost daily. This provides a myriad of choices to consumers but it comes at a cost of heavy competition in the market. Organizations cant afford to release big features after a gap. They tend to ship off small features as releases to the customers at regular intervals so that their products don't get lost in this sea of competition.

Customer satisfaction is now a motto to the organizations which has also become the goal of any product for its success. In order to achieve this, companies need to do the below things:

• Frequent feature deployments
• Reduce time between bug fixes
• Reduce failure rate of releases
• Quicker recovery time in case of release failures.
• In order to achieve the above points and thereby achieving seamless product delivery, DevOps culture acts as a very useful tool. Due to these advantages, multi-national companies like Amazon and Google have adopted the methodology which has resulted in their increased performance.

4. What is the use of SSH?

SSH stands for Secure Shell and is an administrative protocol that lets users have access and control the remote servers over the Internet to work using the command line.

SSH is a secured encrypted version of the previously known Telnet which was unencrypted and not secure. This ensured that the communication with the remote server occurs in an encrypted form.

SSH also has a mechanism for remote user authentication, input communication between the client and the host, and sending the output back to the client.

5. What is the importance of having configuration management in DevOps?

Configuration management (CM) helps the team in the automation of time-consuming and tedious tasks thereby enhancing the organization’s performance and agility.

It also helps in bringing consistency and improving the product development process by employing means of design streamlining, extensive documentation, control, and change implementation during various phases/releases of the project.

6. What does CAMS stand for in DevOps?

CAMS stands for Culture, Automation, Measurement, and Sharing. It represents the core deeds of DevOps.

7. Why is Continuous Integration needed?

By incorporating Continuous Integration for both development and testing, it has been found that the software quality has improved and the time taken for delivering the features of the software has drastically reduced.

This also allows the development team to detect and fix errors at the initial stage as each and every commit to the shared repository is built automatically and run against the unit and integration test cases.

8. What is Continuous Testing (CT)?

Continuous Testing (CT) is that phase of DevOps which involves the process of running the automated test cases as part of an automated software delivery pipeline with the sole aim of getting immediate feedback regarding the quality and validation of business risks associated with the automated build of code developed by the developers.

Using this phase will help the team to test each build continuously (as soon as the code developed is pushed) thereby giving the dev teams a chance to get instant feedback on their work and ensuring that these problems don’t arrive in the later stages of SDLC cycle.

Doing this would drastically speed up the workflow followed by the developer to develop the project due to the lack of manual intervention steps to rebuild the project and run the automated test cases every time the changes are made.

9. What are the three important DevOps KPIs?

Few KPIs of DevOps are given below:

• Reduce the average time taken to recover from a failure.
• Increase Deployment frequency in which the deployment occurs.
• Reduced Percentage of failed deployments.

10. Explain the different phases in DevOps methodology.

DevOps mainly has 6 phases and they are:

Planning:

This is the first phase of a DevOps lifecycle that involves a thorough understanding of the project to ultimately develop the best product. When done properly, this phase gives various inputs required for the development and operations phases. This phase also helps the organization to gain clarity regarding the project development and management process.

Tools like Google Apps, Asana, Microsoft teams, etc are used for this purpose.

Development:

The planning phase is followed by the Development phase where the project is built by developing system infrastructure, developing features by writing codes, and then defining test cases and the automation process. Developers store their codes in a code manager called remote repository which aids in team collaboration by allowing view, modification, and versioning of the code.

Tools like git, IDEs like the eclipse, IntelliJ, and technological stacks like Node, Java, etc are used.

Continuous Integration (CI):

This phase allows for automation of code validation, build, and testing. This ensures that the changes are made properly without development environment errors and also allows the identification of errors at an initial stage.

Tools like Jenkins, circleCI, etc are used here.

Deployment:

DevOps aids in the deployment automation process by making use of tools and scripts which has the final goal of automating the process by means of feature activation. Here, cloud services can be used as a force that assists in upgrade from finite infrastructure management to cost-optimized management with the potential to infinite resources.

Tools like Microsoft Azure, Amazon Web Services, Heroku, etc are used.

Operations:

This phase usually occurs throughout the lifecycle of the product/software due to the dynamic infrastructural changes. This provides the team with opportunities for increasing the availability, scalability, and effective transformation of the product.

Tools like Loggly, BlueJeans, Appdynamics, etc are used commonly in this phase.

Monitoring:

Monitoring is a permanent phase of DevOps methodology. This phase is used for monitoring and analyzing information to know the status of software applications.

Tools like Nagios, Splunk, etc are commonly used.
 

11. What can you say about antipatterns of DevOps?

A pattern is something that is most commonly followed by large masses of entities. If a pattern is adopted by an organization just because it is being followed by others without gauging the requirements of the organization, then it becomes an anti-pattern. Similarly, there are multiple myths surrounding DevOps which can contribute to antipatterns, they are:

• DevOps is a process and not a culture.
• DevOps is nothing but Agile.
• There should be a separate DevOps group.
• DevOps solves every problem.
• DevOps equates to developers running a production environment.
• DevOps follows Development-driven management
• DevOps does not focus much on development.
• As we are a unique organization, we don’t follow the masses and hence we won’t implement DevOps.
• We don’t have the right set of people, hence we cant implement DevOps culture.

12. Can you tell me something about Memcached?

Memcached is an open-source and free in-memory object caching system that has high performance and is distributed and generic in nature. It is mainly used for speeding the dynamic web applications by reducing the database load.

Memcached can be used in the following cases:

• Profile caching in social networking domains like Facebook.
• Web page caching in the content aggregation domain.
• Profile tracking in Ad targeting domain.
• Session caching in e-commerce, gaming, and entertainment domain.
• Database query optimization and scaling in the Location-based services domain.

Benefits of Memcached:

• Using Memcached speeds up the application processes by reducing the hits to a database and reducing the I/O access.
• It helps in determining what steps are more frequently followed and helps in deciding what to cache.

Some of the drawbacks of using Memcached are:

• In case of failure, the data is lost as it is neither a persistent data store nor a database.
• It is not an application-specific cache.
• Large objects cannot be cached.

13. What are the various branching strategies used in the version control system?

Branching is a very important concept in version control systems like git which facilitates team collaboration. Some of the most commonly used branching types are:

Feature branching

• This branching type ensures that a particular feature of a project is maintained in a branch.
• Once the feature is fully validated, the branch is then merged into the main branch.

Task branching

• Here, each task is maintained in its own branch with the task key being the branch name.
• Naming the branch name as a task name makes it easy to identify what task is getting covered in what branch.

Release branching

• This type of branching is done once a set of features meant for a release are completed, they can be cloned into a branch called the release branch. Any further features will not be added to this branch.
• Only bug fixes, documentation, and release-related activities are done in a release branch.
• Once the things are ready, the releases get merged into the main branch and are tagged with the release version number.
• These changes also need to be pushed into the develop branch which would have progressed with new feature development.

The branching strategies followed would vary from company to company based on their requirements and strategies.

14. Can you list down certain KPIs which are used for gauging the success of DevOps?

KPIs stands for Key Performance Indicators. Some of the popular KPIs used for gauging the success of DevOps are:

• Application usage, performance, and traffic
• Automated Test Case Pass Percentage.
• Application Availability
• Change volume requests
• Customer tickets
• Successful deployment frequency and time
• Error/Failure rates
• Failed deployments
• Meantime to detection (MTTD)
• Meantime to recovery (MTTR)

15. What is CBD in DevOps?

CBD stands for Component-Based Development. It is a unique way for approaching product development. Here, developers keep looking for existing well-defined, tested, and verified components of code and relieve the developer of developing from scratch.

16. What is Resilience Testing?

Resilience Testing is a software process that tests the application for its behavior under uncontrolled and chaotic scenarios. It also ensures that the data and functionality are not lost after encountering a failure.

17. Can you differentiate between continuous testing and automation testing?

The difference between continuous testing and automation testing is given below:

18. Tell me something about Ansible work in DevOps

It is a DevOps open-source automation tool which helps in modernizing the development and deployment process of applications in faster manner. It has gained popularity due to simplicity in understanding, using, and adopting it which largely helped people across the globe to work in a collaborative manner.

19. How does Ansible work?

Ansible has two types of servers categorized as:

• Controlling machines
• Nodes

For this to work, Ansible is installed on controlling machine using which the nodes are managed by means of using SSH. The location of the nodes would be specified and configured in the inventories of the controlling machine.

Ansible does not require any installations on the remote node servers due its nature of being agentless. Hence, no background process needs to be executed while managing any remote nodes.

Ansible can manage lots of nodes from a single controlling system my making use of Ansible Playbooks through SSH connection. Playbooks are of the YAML format and are capable to perform multiple tasks.

20. How does AWS contribute to DevOps?

AWS stands for Amazon Web Services and it is a well known cloud provider. AWS helps DevOps by providing the below benefits:

• Flexible Resources: AWS provides ready-to-use flexible resources for usage.
• Scaling: Thousands of machines can be deployed on AWS by making use of unlimited storage and computation power.
• Automation: Lots of tasks can be automated by using various services provided by AWS.
• Security: AWS is secure and using its various security options provided under the hood of Identity and Access Management (IAM), the application deployments and builds can be secured.

21. What can be a preparatory approach for developing a project using the DevOps methodology?

The project can be developed by following the below stages by making use of DevOps:

• Stage 1: Plan: Plan and come up with a roadmap for implementation by performing a thorough assessment of the already existing processes to identify the areas of improvement and the blindspots.
• Stage 2: PoC: Come up with a proof of concept (PoC) just to get an idea regarding the complexities involved. Once the PoC is approved, the actual implementation work of the project would start.
• Stage 3: Follow DevOps: Once the project is ready for implementation, actual DevOps culture could be followed by making use of its phases like version control, continuous integration, continuous testing, continuous deployment, continuous delivery, and continuous monitoring.

22. Do you know about post mortem meetings in DevOps?

Post Mortem meetings are those that are arranged to discuss if certain things go wrong while implementing the DevOps methodology. When this meeting is conducted, it is expected that the team has to arrive at steps that need to be taken in order to avoid the failure(s) in the future.

23. What is the concept behind sudo in Linux OS?

Sudo stands for ‘superuser do’ where the superuser is the root user of Linux. It is a program for Linux/Unix-based systems that gives provision to allow the users with superuser roles to use certain system commands at their root level.

24. Can you explain the “infrastructure as code” (IaC) concept?

As the name indicates, IaC mainly relies on perceiving infrastructure in the same way as any code which is why it is commonly referred to as “programmable infrastructure”. It simply provides means to define and manage the IT infrastructure by using configuration files.

This concept came into prominence because of the limitations associated with the traditional way of managing the infrastructure. Traditionally, the infrastructure was managed manually and the dedicated people had to set up the servers physically. Only after this step was done, the application would have been deployed. Manual configuration and setup were constantly prone to human errors and inconsistencies.

This also involved increased cost in hiring and managing multiple people ranging from network engineers to hardware technicians to manage the infrastructural tasks. The major problem with the traditional approach was decreased scalability and application availability which impacted the speed of request processing. Manual configurations were also time-consuming and in case the application had a sudden spike in user usage, the administrators would desperately work on keeping the system available for a large load. This would impact the application availability.

IaC solved all the above problems. IaC can be implemented in 2 approaches:

• Imperative approach: This approach “gives orders” and defines a sequence of instructions that can help the system in reaching the final output.
• Declarative approach: This approach “declares” the desired outcome first based on which the infrastructure is built to reach the final result.

25. What is ‘Pair Programming’?

Pair programming is an engineering practice where two programmers work on the same system, same design, and same code. They follow the rules of “Extreme Programming”. Here, one programmer is termed as “driver” while the other acts as “observer” which continuously monitors the project progress to identify any further problems.

26. What is Dogpile effect? How can it be prevented?

It is also referred to as cache stampede which can occur when huge parallel computing systems employing caching strategies are subjected to very high load. It is referred to as that event that occurs when the cache expires (or invalidated) and multiple requests are hit to the website at the same time. The most common way of preventing dogpiling is by implementing semaphore locks in the cache. When the cache expires in this system, the first process to acquire the lock would generate the new value to the cache.

27. What are the steps to be undertaken to configure git repository so that it runs the code sanity checking tooks before any commits? How do you prevent it from happening again if the sanity testing fails?

Sanity testing, also known as smoke testing, is a process used to determine if it’s reasonable to proceed to test.
Git repository provides a hook called pre-commit which gets triggered right before a commit happens. A simple script by making use of this hook can be written to achieve the smoke test.

The script can be used to run other tools like linters and perform sanity checks on the changes that would be committed into the repository.

The following snippet is an example of one such script:

#!/bin/shfiles=$(git diff –cached –name-only –diff-filter=ACM | grep ‘.py$’)if [ -z files ]; thenexit 0fiunfmtd=$(pyfmt -l $files)if [ -z unfmtd ]; thenexit 0fiecho “Some .py files are not properly fmt’d”exit 1

The above script checks if any .py files which are to be committed are properly formatted by making use of the python formatting tool pyfmt. If the files are not properly formatted, then the script prevents the changes to be committed to the repository by exiting with status 1.