Jenkins, an open-source automation server, has become an integral part of DevOps, streamlining the software development process and ensuring continuous integration and continuous delivery. With organizations embracing Jenkins more than ever, the need for experts in this field has surged. If you're getting ready for a Jenkins interview, you're in the right place. In this blog, we will be going through the essential Jenkins interview questions, and detailed answers to ensure you're thoroughly prepared.
01 - What is Jenkins?
Jenkins is a free open-source that helps automate various aspects of software development, such as building, testing, and deploying code
It is written in Java.
It allows developers to set up continuous integration and continuous delivery (CI/CD) pipelines that help to build and test the software system with easy integration of changes to the system.
Jenkins follows Groovy Scripting.
It enables developers to continuously check their code and also analyze the post-build actions.
02 - What are the features of Jenkins?
Free and open-source.
Excellent community and documentation.
Build Pipeline Support.
Exhaustive set of plugins and integrations.
Easy to set up, install and use on any platform because it is based on Java.
Supports distributed builds due to master-slave architecture, thus reducing the load on the CI server.
03 - What are the advantages of Jenkins? Why do we use Jenkins?
Jenkins is used for real-time monitoring of extensive codebases, ensuring continuous monitoring. This helps developers to identify and resolve bugs within their code. Additionally, it automatically sends email notifications to developers after their check-ins, making it a seamless post-build action.
Provides great collaboration between the development and operations teams, making it into a single DevOps team
Code errors can be detected as early as possible. Easy bug tracking.
Code deployment is easy and happens in minutes, along with the generation of reports.
Automation of integration work, thereby reducing the number of integration issues.
Automatic changes get updated in the build report with notification.
04 - Mention some of the important plugins in Jenkins.
Maven 2
Gits
Amazon EC2
Join
Copy artifact
Green Balls
HTML Publisher
05 - What is Continuous Integration in Jenkins?
Continuous integration is the process of continuously checking the developer’s code into a version control system and triggering the build to check and identify bugs in the written code.
Jenkins is a prominent continuous integration tool. It facilitates the rapid integration of developers' code into the system. It ensures seamless and efficient bug identification and resolution.
In software development, multiple developers work on various software modules. Integration testing involves integrating all modules for testing.
Integrating code into the source repository is a fundamental development practice.
Whenever a programmer makes changes to the code, it automatically integrates with the system running on the tester's machine.
This streamlined integration process simplifies and speeds up testing tasks for system testers.
06 - What is Groovy in Jenkins?
Groovy from Apache is a language for the Java platform. It is the native scripting language for Jenkins. Groovy-based plugins enhance Jenkins with great interfaces and build reports that are dynamic and consistent.
Jenkins uses a domain-specific language (DSL) called “Groovy” inside a Pipeline Project (read plugin), which will describe a new pipeline as just a script. That single script may articulate a flow that would typically take several “standard” Jenkins jobs chained around.
07 - How can we create a new Jenkins job?
To create a new Jenkins job, follow these steps:
Log in to Jenkins and click on “New Item.”
Enter a name for your job and choose the appropriate job type (freestyle project or pipeline).
Configure the job’s settings, such as source code repository, build triggers, and build steps.
Save your configuration, and Jenkins will start running your job based on the defined settings.
08 - What is Jenkinsfile?
A Jenkinsfile is a text file that contains the pipeline definition for a Jenkins job. It is written in Groovy and resides in the version control repository alongside the source code. Using Jenkinsfiles allows the entire CI/CD pipeline to be versioned, enabling easy collaboration and maintaining consistency.
09 - What is the difference between Continuous Integration, Continuous Delivery, and Continuous Deployment?
The diagram provided below offers a detailed visual explanation of the distinctions between Continuous Integration, Continuous Delivery, and Continuous Deployment.
Continuous Integration: This process entails maintaining the most recent version of the source code in a shared repository accessible to all developers. This ensures that developers can retrieve the latest changes easily, preventing conflicts in the development process.
Continuous Delivery: Manual deployment to production doesn't necessitate deploying every single change.
Continuous Deployment: Automated deployment to production ensures the automatic deployment of every change.
10 - What is Jenkins Pipeline? What is a CI/CD pipeline?
A Jenkins pipeline is a way to define your CI/CD process as code. It allows you to create a series of stages and steps that define the build, test, and deployment workflow. Pipeline scripts can be written using the Groovy language and stored in a version control system for easy management and versioning.
A pipeline is a group of build jobs that are chained and integrated in sequence.
11 - What are the types of Jenkins pipelines?
Jenkins Pipelines can be either – a Declarative pipeline or a Scripted Pipeline. Declarative pipeline makes use of numerous, generic, predefined build steps/stages (i.e. code snippets) to build our job according to our build/automation needs whereas, with Scripted pipelines, the steps/stages can be custom-defined & used using a groovy syntax which provides better control & fine-tuned execution levels.
12 - What are Declarative Pipelines in Jenkins, explain in detail?
Declarative Pipelines are Jenkins enhancements designed to simplify the Groovy syntax of Jenkins pipelines. They introduce some exceptions, such as the elimination of semicolons ';' as statement separators and the requirement for the top-level pipeline to be enclosed within a block.
The common syntax is:
pipeline {
/* Declarative Pipeline */
}
Blocks must contain Sections, Directives, steps or assignments.
pipeline {
agent any
stages {
stage(‘Build’) {
steps {
// Statements…
}
}
stage (‘Test’) {
steps {
// Statements…
}
}
}
}
The above code has 3 major elements:
Pipeline: The block of script contents.
Agent: Defines where the pipeline will start running from.
Stage: The pipelines contain several steps enclosed in the block called Stage.
13 - What is SCM? Which SCM tools are supported in Jenkins?
The SCM or Source Code Management tools Jenkins supports are SVN, Clearcase, CVS, Git, AccuRev, Perforce, RTC, and Mercurial.
Conclusion
Mastering Jenkins is crucial in the DevOps universe! 🚀 With a deep grasp of these key concepts, we pave the path to your success in a Jenkins interview. By thoroughly preparing for these questions and grasping the core principles, we confidently showcase our expertise, securing our dream job in the dynamic world of software development and automation. Remember, practice and hands-on experience with Jenkins are vital! Let's dive in, explore, and automate our way to a brighter future in the tech industry. Best of luck! 🌟
