JENKINS INTERVIEW QUESTIONS

Updated: Aug 10, 2020








Q #1) What is Jenkins?


Answer:Jenkins is a free open source Continuous Integration tool and automation server to monitor continuous integration and delivery. It is written in Java.

It is known as an automated Continuous Delivery tool that helps to build and test the software system with easy integration of changes to the system. Jenkins follows Groovy Scripting.

Also, it enables developers to continuously check in their code and also analyze the post-build actions. The automation testers can use to run their tests as soon as the new code is added or code is modified.


Q #2) What are the features of Jenkins?


Answer: Jenkins comes with the following features:

1. Free open source.

2. Easy installation on various operating systems.

3. Build Pipeline Support.

4. Workflow Plugin.

5. Test harness built around JUnit.

6. Easy upgrades.

7. Rapid release cycle.

8. Easy configuration setup.

9. Extensible with the use of third-party plugins.

Q #3) What are the advantages of Jenkins? Why we use Jenkins?

Answer: Jenkins is used to continuously monitor the large code base in real-time. It enables developers to find bugs in their code and fix them. Email notifications are made to the developers regarding their check-ins as a post-build action.

Advantages of Jenkins are as follows:

  • Build failures are cached during the integration stage.

  • Notifies the developers about build report status using LDAP (Lightweight Directory Access Protocol) mail server.

  • Maven release project is automated with simple steps.

  • Easy bug tracking.

  • Automatic changes get updated in the build report with notification.

  • Supports Continuous Integration in agile development and test-driven development.

Q #4) Mention some of the important plugins in Jenkins?

Answer: Plugins in Jenkins includes:

  • Gits

  • Maven 2 Project

  • HTML Publisher

  • Copy Artcraft

  • Join

  • Green Balls

  • Amazon EC2

Q #5) What is Continuous Integration in Jenkins?

Answer: Continuous integration is the process of continuously checking-in the developer’s code into a version control system and triggering the build to check and identify bugs in the written code.

This is a very quick process and also gives them a chance to fix the bugs. Jenkins is one such continuous integration tool.

In software development, multiple developers work on different software modules. While performing integration testing all the modules are being integrated together. It is considered as the development practice to integrate the code into the source repository

Whenever the programmer/developer makes any change to the current code, then it automatically gets integrated with the system running on the tester’s machine and makes the testing task easy and speedy for the system testers.


Continuous Integration comprises of:

  • Development and Compilation

  • Database Integration

  • Unit Testing

  • Production Deployment

  • Code Labeling

  • Functional Testing

  • Generating and Analysing Reports

Q #6) What is the difference between Hudson and Jenkins?

Answer: There is no difference between Hudson and Jenkins. Hudson was the former name of Jenkins, after going through several issues the name was changed to Jenkins.

Q #7) What is Groovy in Jenkins?

Answer: Groovy is the default scripting language that is being used in the development of JMeter Version 3.1.

Currently Apache Groovy is the dynamic object-oriented programming language that is used as a scripting language for the Java platform. Apache Groovy comes with some useful features such as Java Compatibility and Development Support.


Q #8) Which command is used to start Jenkins?

Answer: You can follow the below-mentioned steps to start Jenkins:

1. Open Command Prompt

2. From the Command Prompt browse the directory where Jenkins. war resides

3. Run the command given below:

D:\>Java –jar Jenkins.war


Q #9) What is Jenkinsfile?

Answer: The text file where all the definitions of pipelines are defined is called Jenkinsfile. It is being checked in the source control repository.

Q #10) What is Jenkins Pipeline? What is a CI CD pipeline?

Answer: The pipeline can be defined as the suite of plugins supporting the implementation and integration of continuous delivery pipelines in Jenkins.

Continuous integration or continuous delivery pipeline consists of build, deploy, test, release pipeline. The pipeline feature saves a lot of time and error in maintaining the builds. Basically, a pipeline is a group of build jobs that are chained and integrated in sequence.

Q #11) What are Scripted Pipelines in Jenkins?

Answer: Scripted Pipeline follows Groovy Syntax as given below:


Node {
           }

In the above syntax, the node is a part of the Jenkins distributed mode architecture, where there are two types of node, Master which handle all the tasks in the development environment and the Agent is being used to handle multiple tasks individually.

Q #12) What are Declarative Pipelines in Jenkins?

Answer: Declarative Pipelines are the newest additions to Jenkins that simplify the groovy syntax of Jenkins pipelines (top-level pipeline) with some exceptions, such as:

No semicolon to be used as a statement separator. The top-level pipeline should be enclosed within block viz;

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.

Q #13) What is SCM? Which SCM tools are supported in Jenkins?

Answer:

  • SCM stands for Source Control Management.