Top Jenkins Interview Question and Answers For 2020

by StarAgile

August 26, 2020
Category DevOps


Life becomes easy when you can build, test, and deploy projects at one time. Isn’t it? Yes, it is now possible with this great tool. It has prominence in the field of DevOps and thus you can quickly crack your interview by mastering a few answers about this tool. Let’s explore that tool and those secret interview questions. We have also provided answers to each question making your life simple. Master these answers to grab a job ASAP.

Basic Jenkins interview questions and answers for beginners 

1) What do you understand about the very word Jenkins?

Jenkins is a continuous integration automation server tool that is based on Java and is an open-source tool used for automated testing.

2) Name at least 2 of the most popular plugins for Jenkins?

The 2 of the plugins for Jenkins that are popular are Maven and Git.

3) Why should developers use Jenkins?

Jenkins is used mostly for its features such as 

4) What is the Pipeline? What are the 3 stages of Jenkins Pipeline?

A pipeline is a process from the early developmental stage until the release of the project. The 3 stages of Jenkins pipeline are as follows,

  • Build the project.
  • Test the project 
  • Deployment of the project.

5) What is Continuous Integration?

It is a method of performing multiple tests on single projects daily. This is required because more than one developer is working on projects such as developing applications or programs.

Key Jenkins interview questions for testers

1) How Jenkins is used in testing?

Jenkins is a continuous integration server and an automated testing tool. Jenkins is used for multiple testing on the same projects daily. The Jenkins pipeline is used here which automates the Build, Test, and Deploy pipeline.

2)  What are automated testing and its advantages? Name the best tool to do this?

Jenkins is the best tool for doing automated testing. Automated testing is the process of using a certain framework or program to test the developed programs or applications automatically without any human intervention.

The advantages are, 

  • Faster testing of the code, 
  • Automated testing saves money and time
  • There is no human intervention required
  • There are no errors because of no human intervention.

  • 3) How do I run a JUnit test in Jenkins?

The following are the steps to run a JUnit test in Jenkins,

  • Open the port 8080 and ensure it is unused on the docker host. Ensure Jenkins is started in the terminal mode.
  • Jenkins is opened in the browser
  • Then the Gradle is used to invoke the pre-build JUnit tests.
  • Ensure that the JUnit test results are reported in Jenkins
  • If the tests failed to verify it in Jenkins

4) How do you write test cases in Jenkins?

  • Open the Jenkins dashboard and then click on the project name and choose the configure option
  • Go to the section of Build and add the build and then choose the invoke ANT option.
  • Then the advanced option is clicked
  • In the section of the build option enters the location of the building code.
  • Then click on the option to add the post-build step and select the option of "Publish JUnit test result report"
  • In the test reports, XML's enter the location and then click on the save option
  • After saving click on the Build Now option.
  • Finally, click on the test results option to check the test results.

5) Why your tests may pass locally but fail in Jenkins?

The Jenkins machine that is the VM or POD or Container is running on the different hardware which might be slower than the local machine the tests with multiple threads or inadvertent race conditions may run differently and fail in Jenkins

Jenkins interview questions and answers for experienced 

1) What is a DSL Jenkins?

The Jenkins "Job DSL and Plugins" are made of 2 parts. The DSL which stands for Domain Specific Language is used for describing the jobs in Groovy-based language and the Jenkins plugins which manage the scripts, the updation of the Jenkins jobs that are created are maintained as the results.

2) What is the difference between Ant, Maven, and Jenkins?

The Ant and Maven are the build tools and Jenkins is the continuous integration tool that has build, test, and deploy features.

3) Which are the SCM tools Jenkins supports?

Jenkins supports a whole lot of tools such as Clearcase, Git, AccuRev, Mercurial, CVS, RTC, Subversion, and can execute Windows batch commands, shell scripts Apache Ant, Apache Maven, and sbt based projects.

4) How to schedule a build in Jenkins?

Under the Job configuration section in Jenkins, we can define various Build Triggers. Now find the Build Triggers section, check the build periodically checkbox and make the schedule by defining the date and the time of the build.

5) What is the blue ocean in Jenkins?

Blue ocean is a project that retraces the user experience of Jenkins, modeling and presenting the process of software delivery with the few clicks to surface the important information and at the same time keeping the extensibility of the core Jenkins.

Top 3 Jenkins pipeline interview questions

1) Why do we use pipelines in Jenkins?

Pipelines add powerful sets of automation tools on to Jenkins, it supports use cases that span from simple continuous integration to fully developed continuous delivery pipelines

The advantages are as follows,

  • Code - Pipelines are implemented in programs and are typically stored in source control, providing the DevOps engineer to edit, review, and iterate on their delivery pipelines.
  • Durability - Pipelines can withstand both the planned and unplanned restart of the Jenkins master
  • Stop - Pipelines can be paused or stopped for user inputs and approval before continuing the run on the pipelines
  • Extensibility - Multiple integrations with other plugins can be done on the pipeline.
  • Versatility - Pipeline can do complex real-world continuous delivery requirements such as fork, join, loop and perform work in parallel

2) What is Jenkinsfile?

A Jenkinsfile is a text file that contains the definition of a Jenkins pipeline and is stored with source control. There are advantages such as,

  • Code review and iteration on the pipeline
  • Pipeline audit trail
  • Single source on the pipeline which can be edited by multiple members on the project.

3) How do you create Multibranch Pipeline in Jenkins?

This enables the DevOps engineer to implement different Jenkinsfile for different branches of the same projects.

It automatically discovers, manages, and executes the pipelines for branches that contain a Jenkinsfile in source control.

Final takeaway: Importance of Jenkins interview questions for DevOps

Jenkins is a versatile tool for controlling the Development side of the DevOps from the start, that is to build, test, and deploy. As seen above the Jenkins pipeline can manage and execute any number of branches of the same project and multiple continuous delivery platforms. Jenkins can support automated testing which provides faster delivery, automated code delivery without human intervention, and saving money and time. Jenkins plays a major role in any DevOps interview. Many interview questions about Jenkins are asked in the DevOps, because of its importance.

These are some of the interview questions on Jenkins. If you want to know more and explore more then register with StarAgile as we offer online interactive DevOps training .