Jenkins Interview Questions & Answers

Top Jenkins Interview Questions

Enlisted below are some of the most popular jenkins Interview Questions

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 continously check in their code and also analyze the post-build actions. The automation testers can use to run thier 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:

1.Build failures are cached during the integration stage.

2.Notifies the developers about build report status using LDAP (Lightweight Directory Access

   protocol) mail server.

3.Maven release project is automated with simple steps.

4.Easy bug tracking.

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

6.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:

1.Gits

2.Maven 2 Project

3.HTML Publish

4.Copy Artcraft

5.Join

6.Green Balls

7.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 Analyzing 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 the difference between Continuous Integration, Continuous Delivery, and Continuous Deployment?

Answer:

Continuous Integration (CI):

    • Definition: CI is a development practice that encourages developers to integrate their code into a shared repository frequently (multiple times a day).
    • Process: Developers submit their code changes to a shared repository. Each integration triggers an automated build and a series of automated tests to ensure that the new changes haven’t introduced errors and that the codebase remains functional.
    • Goal: The primary goal of CI is to catch and address integration issues early in the development process, promoting collaboration and reducing the risk of defects.
  1. Continuous Delivery (CD):
    • Definition: CD is an extension of CI that ensures that the software can be released to production at any time by automating the entire software release process.
    • Process: After successful integration, the code goes through additional automated testing and is automatically deployed to a staging or pre-production environment. The software is kept in a deployable state, and the release to production can be initiated manually.
    • Goal: The main objective of CD is to make the software delivery process reliable and repeatable, allowing for more frequent and predictable releases.
  2. Continuous Deployment (CD):
    • Definition: CD takes the concept of continuous delivery a step further by automatically deploying every code change that passes the automated tests directly to production without manual intervention.
    • Process: Once the automated tests are passed in the staging environment, the code is automatically deployed to the production environment without human intervention.
    • Goal: CD aims to minimize the time between writing code and making it available to users in a production enviro

#11) 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 #12) 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 #13) 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 #14) What is SCM? Which SCM tools are supported in Jenkins?

Answer:

  • SCM stands for Source Control Management.
  • SCM module specifies the source code location.
  • The entry point to SCM is being specified as jenkins_jobs.scm.
  • The job specified with ‘scm’attribute accepts multiple numbers of SCM definitions.

The SCM can be defined as:

scm:

name: eloc-scm

scm:

git:

url: ssh://Jenkins.org/eloc.git

Jenkins supported SCM tools include:

  • CVS
  • Git
  • Perforce
  • AccuRev
  • Subversion
  • Clearcase
  • RTC
  • Mercurial

Q #15) Which CI Tools are used in Jenkin?

Answer: Jenkins supported the following Cl tools:

1. Jenkins

2. GitLab CI

3. Travis CI

4. CircleCI

5. Codeship

6. Go CD

7. TeamCity

8. Bamboo

Q #16) Which commands can be used to start Jenkins manually?

Answer: You can use the following commands to start Jenkins manually:

1. (Jenkins_url)/restart: To force restart without waiting for build completion.

2. (Jenkin_url)/safeRestart: Waits until all the build gets completed before restarting.

Q #17) Which Environmental Directives are used in Jenkins?

Answer: Environmental Directives is the sequence that specifies pairs of the key-values called Environmental Variables for the steps in the pipeline.

Q #18) What are Triggers?

Answer: Trigger in Jenkins defines the way in which the pipeline should be executed frequently. PoliSCM, Cron, etc are the currently available Triggers.

Q #19) What is Agent Directive in Jenkins?

Answer: The Agent is the section that specifies the execution point for the entire pipeline or any specific stage in the pipeline. This section is being specified at the top-level inside the

pipeline block.

Q #20) How to make sure that your project build does not break in Jenkins?

Answer: You need to follow the below-mentioned steps to make sure that the Project build does not break:

1. Clean and successful installation of Jenkins on your local machine with all unit tests.

2. All code changes are reflected successfully.

3. Checking for repository synchronization to make sure that all the differences and changes related to config and other settings are saved in the repository.

Q #21) What is the difference between Maven, Ant, and Jenkins?

Answer: Maven vs Jenkins:

Maven is a build tool like Ant. It consists of a pom.xml file which is specified in Jenkins to run the code. Whereas, is used as a continuous integration tool and automates the deployment process. The reports of the builds can be used to set a mark for continuous delivery as well.

The below table enlists the differences between Maven, Ant, and Jenkins in a comparative way:

Maven Ant Jenkins
It is a Build Automation Tool. Java Library/Command Line Tool. Continuous Integration Tool.
Defines how the software built and describes the software dependencies. Drives build process. Automates the software development with Continuous Integration and facilit Continuous Deliver.
Supports projects written in C#,Ruby. Supports projects written in C and c++. Supports version control tools like Git, AccuRev.
Executes Unit Tests as a part of the normal build cycle. Supports single file execution introduced with Java II. Can execute Apache Ant and Apache

Q #22) How will you define Post in Jenkins?

Answer: Post is a section that contains several additional steps that might execute afterthe completion of the pipeline. The execution of all the steps within the condition block

depends upon the completion status of the pipeline. The condition block includes the following conditions changed success, always, failure, unstable and aborted.

Q #23) What are Parameters in Jenkins?

Answer: Parameters are supported by the Agent section and are used to support various use-cases pipelines. Parameters are defined at the top-level of the pipeline or inside

Hope you like this blog….

Mahesh Wabale
Latest posts by Mahesh Wabale (see all)

Leave a Comment