Jenkins interview Questions
list of the most frequently asked interview questions:
Q1. What is a Jenkins?
Jenkins is open source automation tool written in the Java with plugins built for Continuous Integration-purpose. Jenkins used to build and test software projects.continuously making easier for developers to integrate changes to project, and making it easier for the users to obtain a fresh build. It also allows to continuously deliver your software by integrating with large number of testing and deployment of technologies.
● First, developer commits the code to source code repository. Meanwhile,
Jenkins server checks repository at regular time intervals for changes.
● Soon after commit occurs, the Jenkins server detects changes that have
occurred in source code repository. Jenkins will pull those changes ,will
start preparing a new build.
● If the build fails, then concerned team will be notified.
● If built successful, then Jenkins deploys built in the test server.
● After testing, Jenkins generates a feedback then notifies developers about
build and the test results.
● It will continue to check source code repository for the changes made in t
source code and then whole process keeps on repeating.
Q2. Discuss benefits of using Jenkins?
● At the integration stage, build failures are cached.
● For eachand every change in the source code an automatic build report notification is
generated.
● To notify the developer about build report success or failure, it is integrated with the LDAPmail server.
● Achieves continuous integration with agile development and test driven development.
● With the simple steps, maven release project is automated regularly.
● Easy tracking of the bugs at early stage in development environment than production.
Q3. What are pre-requisites for using the Jenkins
● source code repository is accessible, for instance, Git repository.
● working build script, like Maven script, checked into the repository.
Q4. List some of the useful plugins in Jenkins?
Below are some of important Plugins:
● Maven 2 project
● Amazon EC2 , HTML publisher
● Copy artifact
● Join
● Green Balls
Q5. what are the commands used to start Jenkins
manually?
To start Jenkins open Console or Command line, then go to Jenkins
installation-directory. Over there you can use below commands:
1. start Jenkins: jenkins.exe start
2. stop Jenkins: jenkins.exe stop
3. restart Jenkins: jenkins.exe restart
Q6. Explain how to set up Jenkins job?
First mention how to create Jenkins job.
1.Go to Jenkins top page and select “New Job”, next choose “Build free-style softwareproject”.
Elements of this freestyle job:
● Optional SCM, such as CVS / Subversion where your source code resides.
● Optional triggers the control when Jenkins will performs build.
● Some sort of the build script that performs the build like ant, maven/shell script, batch and file . where the real work starts.
● Optional steps to collect the information out of build, such as archiving the artifacts
and/or recording javadoc and test results.
● There other Optionas to notify other people/systems with the build result, such as sending
e-mails, IMs, updating issue tracker, etc..
Q7. Explain how to create a backup and copy files in Jenkins?
To create backup you need to do is periodically back up your JENKINS_HOME directory. This contains all of your build jobs configurations, your slave node
configurations, your build history. To create back-up of your Jenkins setup, copy this directory. You can also copy job directory to clone or replicate job or rename directory.
Q8. How to secure Jenkins?
● Ensure that global security is on.
● Ensure Jenkins is integrated with the company’s user directory with
the appropriate plugin.
● Ensure matrix/Project matrix is enabled to fine tune access.
● Automate process of setting rights or privileges in Jenkins with the custom version of controlled script.
● Limit physical access to the Jenkins data/folders.
● Periodically run the security audits on same.
Q9 Explain how you can we deploy a custom build of core plugin?
Below are steps to deploy custom build of the core plugin:
● Stop the Jenkins.
● Copy custom HPI to the $Jenkins_Home/plugins.
● Delete e previously expanded plugin directory.
● Make an empty file called as .hpi.pinned.
● Start the Jenkins.
Q10. Explain relation between Hudson and Jenkins?
Hudson was the earlier name and version of current Jenkins. After
some issue, project name changed from Hudson to Jenkins.
Q11. What do you do when you see the broken build for your project ?
Open the console output for the broken build and try to see if any file changes missed. If unable to find the issue in that way, then clean and updatelocal workspace to replicate problem and try to solve it.
Q12. Explain how to move or copy Jenkins from one server to other server?
There are multiple ways :
● Move the job from one installation of the Jenkins to the another by simply copying corresponding job directory.
● Make copy of existing job.
● Rename existing job by renaming directory. Note that if you change job
name you will need to change other job that tries to call the renamed job.
Q13. Mention various ways which build can be scheduled in the
Jenkins?
● By following source code management commits
● After the completion of other builds
● Can scheduled to run at specified time slots
● Manual Build up Requests.
Q14.Differentiate between Ant , Maven and Jenkins?
Ant and Maven are Build Technologies where as the Jenkins is continuous integration tool.
Q15. list SCM tools that Jenkins supports?
Below are the Source code management tools supported by the Jenkins:
● AccuRev
● CVS,
● Subversion,
● Git,
● Mercurial,
● Perforce,
● Clearcase
● RTC
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