Devops Engineer Interview Questions and Answers Pdf

11. How will you run a script automatically when a developer commits a change into GIT?
Answer: GIT provides the feature to execute custom scripts when a certain event occurs in GIT. This feature is called hooks.

We can write two types of hooks.
Client-side hooks
Server-side hooks
For this case, we can write a Client-side post-commit hook. This hook will execute a custom script in which we can add the message and code that we want to run automatically with each commit.

12. What are the main features of AWS OpsWorks Stacks?
Answer: Some of the main features of AWS OpsWorks Stacks are as follows:
Server Support: AWS OpsWorks Stacks we can automate operational tasks on any server in AWS as well as our own data center.

Scalable Automation: We get automated scaling support with AWS OpsWorks Stacks. Each new instance in AWS can read configuration from OpsWorks. It can even respond to system events in the same way as other instances do.
Dashboard: We can create dashboards in OpsWorks to display the status of all the stacks in AWS.

Configuration as Code: AWS OpsWorks Stacks are built on the principle of “Configuration as Code”. We can define and maintain configurations like application source code. The same configuration can be replicated on multiple servers and environments.

Application Support: OpsQorks supports almost all kinds of applications. So it is universal in nature.

13. How does CloudFormation work in AWS?
Answer: AWS CloudFormation is used for deploying AWS resources.
In CloudFormation, we have to first create a template for a resource. A template is a simple text file that contains information about a stack on AWS. A stack is a collection of AWS resourced that we want to deploy together in an AWS as a group.

Once the template is ready and submitted to AWS, CloudFormation will create all the resources in the template. This helps in automation of building new environments in AWS.

14. What is the major variance between the Linux and Unix operating systems?
Answer:
Unix:

It fits the family of multitasking, multiuser operating systems.
These are typically used in internet servers and workstations.
It is initially derivative from AT&T Unix, industrialized starting in the 1970s at the Bell Labs study center by Ken Thompson, Dennis Ritchie, and others.
Equally the operating systems are open source but UNIX is comparatively alike one as associated with LINUX.
Linux:

Linux has perhaps been home to every programming language recognized to humankind.
These are cast-off for personal computers.
The LINUX is founded on the kernel of the UNIX operating system.

15. What are the best practices of Continuous Integration (CI)?
Answer: Some of the best practices of Continuous Integration (CI) are as follows:

Build Automation: In CI, we create such a build environment that even with one command build can be triggered. This automation is done all the way up to deployment to the Production environment.
Main Code Repository: In CI, we maintain the main branch in a code repository that stores all the Production-ready code. This is the branch that we can deploy to Production at any time.
Self-testing build: Every build in CI should be self-tested. It means with every build there is a set of tests that runs to ensure that changes are of high quality.
Every day commits to baseline: Developers will commit all of their changes to baseline every day. This ensures that there is no big pileup of code waiting for integration with the main repository for a long time.
Build every commit to baseline: With Automated Continuous Integration, every time a commit is made into baseline, a build is triggered. This helps in confirming that every change integrates correctly.
Fast Build Process: One of the requirements of CI is to keep the build process fast so that we can quickly identify any problem.
Production like environment testing: In CI, we maintain a production-like environment also known as pre-production or staging environment, which is very close to the Production environment. We perform testing in this environment to check for any integration issues.
Publish Build Results: We publish build results on a common site so that everyone can see these and take corrective actions.
Deployment Automation: The deployment process is automated to the extent that in a build process we can add the step of deploying the code to a test environment. On this test environment, all the stakeholders can access and test the latest delivery.

16. What are the benefits of Continuous Integration (CI)?
Answer: The benefits of Continuous Integration (CI) are as follows:

CI makes the current build constantly available for testing, demo and release purpose.
With CI, developers write modular code that works well with frequent code check-ins.
In case of a unit test failure or bug, a developer can easily revert back to the bug-free state of the code.
There is a drastic reduction in chaos on release day with CI practices.
With CI, we can detect Integration issues much earlier in the process.
Automated testing is one very useful side effect of implementing CI.
All the stakeholders including business partners can see the small changes deployed into pre-production environment. This provides early feedback on the changes to the software.
Automated CI and testing generate metrics like code-coverage, code complexity that help in improving the development process.

17. What are the options for security in Jenkins?
Answer: In Jenkins, it is very important to make the system secure by setting user authentication and authorization. To do this we have to do the following:

First, we have to set up the Security Realm. We can integrate Jenkins with the LDAP server to create user authentication.
The second part is to set authorization for users. This determines which user has access to what resources.
In Jenkins some of the options to set up security are as follows:

We can use Jenkins’ own User Database.
We can use the LDAP plugin to integrate Jenkins with the LDAP server.
We can also setup Matrix-based security on Jenkins.

18. What are the main benefits of Ansible?
Answer: Ansible is a powerful tool for IT Automation for large scale and complex deployments. It increases the productivity of the team.

Some of the main benefits of Ansible are as follows:

Productivity: It helps in delivering and deploying with speed. It increases productivity in an organization.
Automation: Ansible provides very good options for automation. With automation, people can focus on delivering smart solutions.
Large-scale: Ansible can be used in small as well as very large-scale organizations.
Simple DevOps: With Ansible, we can write automation in a human-readable language. This simplifies the task of DevOps.

19. What are the main use cases of Ansible?
Answer: Some of the popular use cases of Ansible are as follows:

App Deployment: With Ansible, we can deploy apps in a reliable and repeatable way.
Configuration Management: Ansible supports the automation of configuration management across multiple environments.
Continuous Delivery: We can release updates with zero downtime with Ansible.
Security: We can implement complex security policies with Ansible.
Compliance: Ansible helps in verifying an organization’s systems in comparison with the rules and regulations.
Provisioning: We can provide new systems and resources to other users with Ansible.
Orchestration: Ansible can be used in orchestration of complex deployment in a simple way.

20. What is Docker Hub?
Answer: Docker Hub is a cloud-based registry. We can use Docker Hub to link code repositories. We can even build images and store them in Docker Hub. It also provides links to Docker Cloud to deploy the images to our hosts.
Docker Hub is a central repository for container image discovery, distribution, change management, workflow automation, and team collaboration.

31. What are the main services of AWS that you have used?
Answer: We use the following main services of AWS in our environment:

EC2: This is the Elastic Compute Cloud by Amazon. It is used for providing the computing capability to a system. We can use it in places of our standalone servers. We can deploy different kinds of applications on EC2.
S3: We use S3 on Amazon for our storage needs.
DynamoDB: We use DynamoDB in AWS for storing data in the NoSQL database form.
Amazon CloudWatch: We use CloudWatch to monitor our application in Cloud.
Amazon SNS: We use the Simple Notification Service to inform users about any issues in a Production environment.
32. Why GIT is considered better than CVS for version control system?

Answer: GIT is a distributed system. In GIT, any person can create its own branch and start checking in the code. Once the code is tested, it is merged into main GIT repo. IN between, Dev, QA, and product can validate the implementation of that code.

In CVS, there is a centralized system that maintains all the commits and changes.
GIT is open source software and there are plenty of extensions in GIT for use by our teams.

33. What is the difference between a Container and a Virtual Machine?
Answer: We need to select an Operating System (OS) to get a specific Virtual Machine (VM). VM provides full OS to an application for running in a virtualized environment.

A Container uses APIs of an Operating System (OS) to provide a runtime environment to an application.
A Container is very lightweight in comparison with a VM.
VM provides a higher level of security compared to a Container.
A Container just provides the APIs that are required by the application.
34. What is Serverless architecture?
Answer: Serverless Architecture is a term that refers to the following:

An application that depends on a third-party service.
An Application in which Code is run on ephemeral containers.
In AWS, Lambda is a popular service to implement Serverless architecture.
Another concept in Serverless Architecture is to treat code as a service or Function as a Service (FAAS). We just write code that can be run on any environment or server without the need of specifying which server should be used to run this code.
35. What are the main principles of DevOps?
Answer: DevOps is different from Technical Operations. It has the following main principles:

Incremental: In DevOps, we aim to incrementally release software to production. We do releases to production more often than Waterfall approach of one large release.
Automated: To enable users to make releases more often, we automate the operations from Code Check in to deployment in Production.
Collaborative: DevOps is not the only responsibility of the Operations team. It is a collaborative effort of Dev, QA, Release and DevOps teams.
Iterative: DevOps is based on an Iterative principle of using a process that is repeatable. But with each iteration, we aim to make the process more efficient and better.
Self-Service: In DevOps, we automate things and give self-service options to other teams so that they are empowered to deliver the work in their domain.
36. Are you more Dev or more Ops?
Answer: This is a tricky question. DevOps is a new concept and in any organization, the maturity of DevOps varies from highly Operations oriented to highly DevOps oriented. In some projects, teams are very mature and practice DevOps in their true form. In some projects, teams rely more on the Operations team.

As a DevOps person, I give first priority to the needs of an organization and project. At some times I may have to perform a lot of operations work. But with each iteration, I aim to bring DevOps changes incrementally to an organization.

Over time, the organization/project starts seeing results of DevOps practices and embraces it fully.

37. What is the REST service?
Answer: REST is also known as Representational State Transfer. A REST service is a simple software functionality that is available over HTTP protocol. It is a lightweight service that is widely available due to the popularity of the HTTP protocol.

Since REST is lightweight; it has very good performance in a software system. It is also one of the foundations for creating highly scalable systems that provide a service to a large number of clients.

Another key feature of a REST service is that as long as the interface is kept the same, we can change the underlying implementation. E.g. Clients of REST service can keep calling the same service while we change the implementation from php to Java.

38. What are the Three Ways of DevOps?

Answer: Three Ways of DevOps refers to three basic principles of DevOps culture. These are as follows:
The First Way: Systems Thinking: In this principle, we see the DevOps as a flow of work from left to right. This is the time taken from Code check into the feature being released to an End customer. In DevOps culture, we try to identify the bottlenecks in this.

The Second Way: Feedback Loops: Whenever there is an issue in production it is feedback about the whole development and deployment process. We try to make the feedback loop more efficient so that teams can get the feedback much faster. It is a way of catching defect much earlier in a process than it is reported by a customer.
The Third Way: Continuous Learning: We make use of first and second-way principles to keep on making improvements in the overall process. This is the third principle in which over the time we make the process and our operations highly efficient, automated and error-free by continuously improving them.
39. How do you apply DevOps principles to make system Secure?

Answer: Security of a system is one of the most important goals for an organization. We use the following ways to apply DevOps to security. Automated Security Testing: We automate and integrate Security testing techniques for Software Penetration testing and Fuzz testing in the software development process.

Early Security Checks: We ensure that teams know about the security concerns at the beginning of a project, rather than at the end of delivery. It is achieved by conducting Security training and knowledge sharing sessions.
Standard Process: At DevOps, we try to follow the standard deployment and development process that has already gone through security audits. This helps in minimizing the introduction of any new security loopholes due to the change in the standard process.
40. What is Self-testing Code?
Answer: Self-testing Code is an important feature of DevOps culture. In DevOps culture, development team members are expected to write self-testing code. It means we have to write code along with the tests that can test this code. Once the test passes, we feel confident to release the code.

If we get an issue in production, we first write an automation test to validate that the issue happens in the current release. Once the issue in release code is fixed, we run the same test to validate that the defect is not there. With each release, we keep running these tests so that the issue does not appear anymore.
One of the techniques of writing Self-testing code is Test Driven Development (TDD).