Common Jenkins Interview Questions (With Sample Answers)

Updated 30 September 2022

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Jenkins is an open-source automation server that helps automate the software development process of building, testing, deploying and facilitating continuous integration of software fixes and their delivery. Hiring managers may ask you about Jenkins when you appear for software development job interviews because it is an important part of the development process. Learning about the common Jenkins interview questions can help you prepare for a job interview. In this article, we discuss some commonly asked Jenkins interview questions and share sample answers with tips to help guide your preparation process.

Common Jenkins interview questions

Here is a list of Jenkins interview questions to review to help prepare for your next interview:

Describe how would you use Jenkins to perform testing on a web application?
Can you describe some common challenges with multi-domain deployment?
How does Jenkins perform version control?
Can you explain how Jenkins uses services?
Describe how to set up a remote repository in Jenkins?

Interview questions about Jenkins and example answers

Some common Jenkins interview questions include the following:

1. Describe Jenkins.

Asking this helps employers evaluate your theoretical and practical understanding of this software tool. They may also want to assess if your prior knowledge and expertise in the area has equipped you with the relevant skill set to develop and implement programs using this tool. When answering this question, consider sharing the meaning and importance of this software in the overall development process.

Example: 'Jenkins is an open-source automation software tool that is self-contained and performs the automation tasks related to building, testing, delivering and deploying various software. It is a continuous integration (CI) and a continuous delivery and deployment (CD) automation tool that uses the Java programming language. Developers and programmers use this automation tool to implement various CI/CD workflows, also commonly known as pipelines.

Pipelines help detect faults in a codebase and build the software while automating the testing of their builds, preparing the deployment code and eventually deploying code to containers and virtual machines. As a software professional, you can install Jenkins using native system packages, Docker, or even run it independently with any device that has a Java runtime environment or JRE pre-installed.'

2. What can a software developer use Jenkins for?

Employers can ask you this question to find out if you know the specific purposes for which software professionals use this self-contained server. They may want to determine if you are aware of the technical aspects involved and assess your suitability for the vacancy. You may want to be specific and describe some primary reasons for using Jenkins to support your response.

Example: 'During my time at ABC technicals as a software developer, I used Jenkins to perform various tasks, from everyday developer tasks like integration, deployment and regression testing to complex deployment and delivery tasks. As part of my technical projects, I also used this software tool to build projects through automation that often varied in their components and texture.

Using Jenkins, I could work on some incredible projects that required multiple languages in their user interface like Java, PHP and R. This software server is helpful for automation testing, including unit and functional testing. I can also use Jenkins to deploy project artefacts like JAR or WAR files.'

3. Can you explain the meaning of CI/CD?

Employers may ask you this to assess your technical expertise and proficiency in using the Jenkins software. They may want to know if you have the core knowledge to differentiate and highlight the important aspects of each of these concepts. When answering this question, consider mentioning the relevant features of each of these domains and try to remain specific without adding unrelated information.

Example: 'In software development, CI refers to a process where developers integrate the changes made to the software into the main code whenever a patch is ready. This process helps ensure that the software is always ready for testing, building, deployment and monitoring. It is a software development process where developers continually test and deploy the CI changes in a specific environment.

This process leads to a manual review once the software professionals mark the quality checks as successful. CD is a software development process where developers automatically deploy the CI changes into the target environment once the quality checks succeed.'

4. Can you define the Jenkins pipeline?

This concept is dynamic, so employers can ask you this question to evaluate your expertise in the subject area and industry knowledge. They may also want to assess if you can highlight the relevant aspects of this concept and its critical features while establishing your aptitude for the technical aspects of the job. When answering this question, consider explaining the meaning and definition of the Jenkins pipeline, its essential characteristics and some of its types to add substance to your answer.

Example: 'Jenkins pipeline refers to a type of job or sequence of steps controlled by defined and specified logic. It directs various long-running activities spanning multiple build agents and is suitable for building pipelines, previously called workflows. It helps organise complex activities easier than using a freestyle method. There are two common types of Jenkins pipelines: one is the declarative pipeline, and the other is the scripted pipeline.

The declarative pipeline uses generic, pre-defined build steps or stages, known as code snippets, to build a job based on specific build or automation needs. The scripted pipeline lets you customise steps and stages using a ‘groovy syntax' to increase control and enhance execution levels.'

5. What is a Jenkins shared library, and how is it useful?

This question evaluates your conceptual understanding as shared libraries form a key part of the Jenkins server. With this question, the employers may want to assess your subject knowledge and determine if you are familiar with this concept. When answering, consider describing the meaning of the concept and explaining some of its important uses for software professionals.

Example: 'As pipeline jobs increase, so can the possibility of the code duplicating. This is because a part of the build/automation process can remain the same for most of these jobs, causing possible duplication of the same code in other jobs. The Jenkins project developed the shared libraries' concept to help make updating code easier on all jobs and avoid duplications.

Shared libraries are codes available across multiple pipelines that professionals maintain separately. Apart from preventing replication, they help improve the pipeline code's overall maintenance, modularity and readability. Shared libraries can help enhance the automation process for new or any upcoming pipeline jobs.'

6. What happens when a Jenkins agent is offline? How do you deal with such a situation?

This question aims to assess your technical expertise in Jenkins. Employers can ask you this to assess your problem-solving and decision-making skills. They may also want to see if you have ever faced a situation like this before and what specific strategies you used to overcome it and find a solution. When answering this question, consider highlighting how it affects workflow when an agent is offline. Sharing your personal experience can help make the answer more specific and relevant to the position and help the employer understand how you work better.

Example: 'When a job relates to a specific node or agent, only that agent can perform it. If the target node is offline and all others are busy, a triggered job waits until the agent comes online or another becomes available. When this happens, a job can remain waiting without recognising that the target node is offline. Attaching jobs to several nodes/agents and 'labelling' them reduces the chance of this happening. When you connect a job to a label, any node or agent in that label can fulfil it. This also helps reduce overall turnaround time.'

7. Describe the blue ocean from a user experience perspective.

Blue ocean forms a fundamental aspect of the Jenkins user experience. So, when employers ask you this question, they may want to see your level of practical understanding and knowledge of this aspect of Jenkins. They may also assess whether your qualifications and technical expertise have equipped you with strategic thinking to develop ways to enhance the user experience. When answering this question, consider highlighting the definition and essential features of the concept while explaining each of its relevant components.

Example: 'When I worked as a software developer with ABC Softicals, I often referred to the blue ocean and its applications for redefining and enhancing the overall user experience for our digital products. In Jenkins, the blue ocean refers to the redefined user experience and works specifically with the Jenkins pipeline. In my experience, I've learned to access and familiarise myself with its various features. One of its aspects that I found highly intriguing is its high compatibility with various freestyle jobs, which also helped increase clarity.

For my projects, I could also access the visualisation of CD pipelines, which helped enable fast and intuitive comprehension of the pipeline's status. Last, its pipeline editor features helped me to make the pipeline creation process more accessible for our users through an intuitive and visual process.'

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