Friday, May 5, 2023

21 Jenkins and CI/CD Interview Questions for Java Developers and DevOps (with Answers)

Hello guys, if you are preparing for Java developer interview or a DevOps Engineering interview then you must prepare for Jenkins related interview questions. Jenkins is one of the most essential tool for creating build, test, and deploy pipelines in Java world and almost every company and project you work will need a Jenkins pipeline for automation. If you are joining as junior developer then most likely you will already find the pipelines setup for you and you only need to customize it or modify based upon new requirements but if you are joining as an experienced developers or DevOps Engineer and its a green field project then you will most likely need to do all the hard work and setup those Jenkins  pipelines from scratch, and its not possible without a good, solid knowledge of how Jenkins works and different plugins.

As a senior Java developer I have worked on both side but more on the user side then the DevOps side who are responsible for setting and managing Jenkins pipelines, installing Jenkins agents, and doing all kind of setup.  

While Jenkins questions never is the main part of any Java developer interview, they are quite important and you will find one or two questions related to tools and practices about Jenkins, but things changes completely if you are interviewing for DevOps, there you will have to be prepared for more in-depth and hands-on explanation of Jenkins questions.

If you are looking for good Jenkins questions for both beginner and experienced level then you have come to the right place. Earlier, I have shared Docker questions, Kubernetes questions, DevOps Questions, Maven Question and Git interview questions, all of those are important for DevOps Engineer interview and in this article, I am going to share 21 common Jenkins and CI/CD interview questions with answers.

If you have used Jenkins or worked with Jenkins then you can answer all of these questions very easily but if you struggle to answer them then you should join one of these best Jenkins online courses to learn or revise key Jenkins concepts. If you know Jenkins then it doesn't take much time to revise key concepts but if you are new to Jenkins, you should set aside a couple of days to learn Jenkins in depth.

21 Jenkins and CI/CD Interview Questions with Answers

After struggling for too long to pass any Jenkins interview, you are finally going to get the solution. You don’t have to struggle anymore and you can find the right guide that will take you to your success as far as Jenkins interview is concerned. 

It is very easy to pass. You just have to know and understand the questions that are commonly asked in Jenkins interviews. Knowing questions is not enough, you also need to know the right answers to those questions and that is why this article has got you covered. Below are the top 20 Jenkins interview questions with answers.

1. What is Jenkins?
Answer: Jenkins is an open-source free automation tool used to build and test software projects. The tool makes it painless for developers to integrate changes to the project. Jenkins' primary focus is to keep track of the version control system and initiate and monitor a build system if there are any changes.

2. What are the features of Jenkins?

  • It is a free and open-source automation tool
  • Jenkins provides a vast number of plugins
  • It is easy to set up and install on multiple operating systems
  • Provides pipeline support
  • Fast release cycles
  • Easy upgrades

3. What are the steps of installing Jenkins?
Answer: the steps are as follows:

  • Install Java
  • Install Apache Tomcat Server
  • Download Jenkins war File
  • Deploy Jenkins war File

4. What are the three different types of Jenkins pipelines?

  • CI/CD pipeline
  • Scripted pipeline
  • Declarative pipeline

5. What are the advantages of Jenkins?

  • At integration stage, build failures are cached
  • For each code commit changes an automatic build report notification generates
  • To notify developers about build report success or failure, it is integrated with LDAP mail server
  • Achieves continuous integration agile development and test driven development
  • With simple steps, maven release project is automated
  • Easy tracking of bugs at early stage in development environment than production

6. What are some of the important plugins in Jenkin?

  • Maven 2 project
  • Amazon EC2
  • HTML publisher
  • Copy artifact
  • Join
  • Green Balls

7. What is continuous integration in Jenkins?
Answer: Continuous integration is the process in which all development work integration is done at the earliest and a code is continuously tested after a commit. This process allows one to discover bugs at an early stage and fix them. The Jenkins build server provides this functionality.

What is continuous integration in Jenkins?

8. What is the Blue Ocean?
Answer: Blue Ocean is the redefined user experience for Jenkins. Designed from the ground up for Jenkins Pipeline, it is still compatible with freestyle jobs, Blue Ocean reduces clutter and increases clarity.

9. What are the main features of Blue Ocean?

  • Sophisticated visualizations of continuous delivery (CD) Pipelines, allowing for fast and intuitive comprehension of your Pipeline’s status.
  • Pipeline editor - makes the creation of Pipelines approachable by guiding the user through an intuitive and visual process to create a Pipeline.
  • Personalization to suit the role-based needs of each member of the team.
  • Pinpoint precision when intervention is needed and/or issues arise. Blue Ocean shows where in the pipeline attention is needed, facilitating exception handling and increasing productivity.
  • Native integration for branch and pull requests, enables maximum developer productivity when collaborating on code with others in GitHub, Bitbucket, etc.

10. What are the pre-requisites for using Jenkins?

  • A source code repository which is accessible, for instance, a Git repository.
  • A working build script, e.g., a Maven script, checked into the repository.

11. What are the types of jobs or projects in Jenkins?

  • A Freestyle project
  • Maven project
  • Pipeline
  • Multibranch pipeline
  • External Job
  • Multi-configuration project
  • Github organization

12. What is continuous testing?
Answer: Continuous Testing is the process where you execute automated tests as part of the software delivery pipeline. This is done so that you get feedback on the business risks associated with software as early as possible. It consists of evolving and extending test automation to address the increased complexity and pace of modern application development and delivery.

13. What is Jenkinsfile?
Answer: A Jenkinsfile is essentially a text file containing the steps for running a Jenkins Pipeline and is registered into the source control repository of a project.

14. How do you create a slave node in Jenkins?
Answer: You can create it as follows:

  • Go to Manage Jenkins, and scroll down to Manage Nodes
  • Click on New Node
  • Set the node name, choose the Dumb slave option, and then click on OK
  • Enter the node slave machine details, and click on Save

15. What is the use of the JENKINS HOME directory?
Answer: JENKINS_HOME directory is used to store all the settings, configurations, and logs. 

16. What are declarative pipelines?
Answer: A declarative pipeline is a new feature in Jenkins that maintains the pipeline as a code and makes it easier to write and read. It is defined within a block labeled pipeline.

17. What is DSL Jenkins?
Answer: Job DSL is one of the most important plugins for Jenkins that allows managing configuration as code. It is made up of two parts: Domain Specific Language (DSL) which enables users to define jobs utilizing a Groovy-based language, and then a Jenkins plugin that manages the scripts and updates the created Jenkins jobs.

18. What are the SCM tools that Jenkins supports?
Answer: The SCM or Source Code Management tools Jenkins supports are SVN, Clearcase, CVS, Git, AccuRev, Perforce, RTC, and Mercurial.

19. How can You Clone a Git Repository via Jenkins?
Answer: To create a clone repository via Jenkins you need to use your login credentials in the Jenkins System. To achieve the same you need to enter the Jenkins job directory and execute the git config command.

How can You Clone a Git Repository via Jenkins

20. What is the use of the Backup plugin in Jenkins?
Answer: Jenkins Backup Plugin is used to back up the critical configurations and settings in order to use them in the future in case of any failure or as per the need of time.

21. Does Jenkins use a shared library?
Answer: Yes, Jenkins has an integrated feature where developers can use shared libraries.

That's all about frequently asked Jenkins and CI/CD Interview Questions with answers for developers and DevOps. Struggling to pass interviews is surely going to end because you have the solution right in your hands. The interview will be so easy because you have the answers to the questions that the interview panel will ask. You are the one to make it. Believe in yourself and you will leave the interview room feeling proud of yourself. Success is all yours.

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Thanks for reading this article so far. All the best for your DevOps or Jenkins interviews and if you have any questions which don't know answer or any doubt feel free to ask in comments. You can also drop a comment if you have any doubts about Ansible, and we will get back to you as soon as possible.

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