Top Jenkins(2021) Interview Questions | CodeUsingJava
















Top Jenkins Interview Questions


  1. What is Jenkins?
  2. What is Continuous Integration?
  3. What is a Jenkins Pipeline?
  4. How does the Jenkins Pipeline works?
  5. What are the types of Jenkins pipelines?
  6. What are the ways to trigger a Jenkins Job/Pipeline?
  7. How can we reset Jenkins security settings from the command line?
  8. How to set environment variables in Jenkins?
  9. Which SCM tools does Jenkins support?
  10. What command is used to start Jenkins?
  11. What are the useful plugins in Jenkin?
  12. What is Groovy?
  13. Explain DSL Jenkins?

What is Jenkins?

Jenkins is an automation server which is used us in automating all sorts of tasks related building, testing and delivering software, it can be installed by native system packages, docker and can run standalone by machine with Java Runtime Environment installed.
Jenkins is built for Continuous Integration Purpose, it is used in helping the developers and testers work in tandem for detecting and closing defects early in software development lifecycle and encourage automated testing of builds.


What is Continuous Integration?

Continuous Integration helps in the processing of continuously checking the developer's code in a version control system several times and automating for checking and detecting bugs in written code.
Continuous Integration includes the following options:
Development and Compilation
Database Integration
Unit Testing
Production Deployment
Code Labeling
Functional Testing
Generating and Analyzing Reports


What is a Jenkins Pipeline?

Jenkins Pipeline is a sequence of steps controlled by the defined logic, it is long running activities which can span accross multiple build agents.It is suitable for building pipeline and in organizing complex activities which cannot be easily achieved using freestyle job.

How does the Jenkins Pipeline works?


Jenkins


What are the types of Jenkins pipelines?

There are 2 types of jenkins pipeline:
Declarative Pipeline is used in bulding numerous, generic, predefined stages and automating needs.
Scripted Pipeline is used in using grovy syntax that provides control and fine tune execution levels.


What are the ways to trigger a Jenkins Job/Pipeline?

There are many ways we can trigger Jenkins pipelines are as follows:
Trigger an API (POST) request to the target job URL with the required data.
Trigger it manually from the Jenkins web application.
Trigger it using Jenkins CLI from the master/slave nodes.
Time-based Scheduled Triggers like a cron job.
Event-based Triggers like SCM Actions, WebHooks, etc.
Upstream/Downstream triggers by other Jenkins jobs.


How can we reset Jenkins security settings from the command line?

We can reset Jenkins by using the following code:

sudo service jenkins restart




How to set environment variables in Jenkins?

Environment cannot be set unless and until we use the following code:
AOEU=$(echo aoeu)



Which SCM tools does Jenkins support?

SCM tools supproted by Jenkins are AccuRev, CVS, Subversion, Git, Mercurial, Perforce, Clearcase and RTC.

What command is used to start Jenkins?

E:\>Java -jar Jenkins.war


What are the useful plugins in Jenkin?

Maven 2 project
Amazon EC2
HTML publisher
Copy artifact
Join
Green Balls


What is Groovy?

Grovy is an open source, automated and integrated server used by the development teams throughout the world.It is a language designed for Java Platform, used in orchestrate our pipeline and can be contributing in different languages and also as a scripting languages for the Java Platform.

Explain DSL Jenkins?

Jenkins Domain Specific Language(DSL) can be defined in a programmatic manner that is human readable, the UI configuration are intuitively translated in the code.We can create versions for the job and also maintains the changes.It is a converted code is Grovy based language.
The defination of the parameter is given below in the config.xml file:
<hudson.model.StringParameterDefinition>
 <name>MESSAGE</name>
 <defaultValue>Welcome to Codeusingjava</defaultValue>
</hudson.model.StringParameterDefinition>
The corresponding code will look like:
parameters {
 stringParam('MESSAGE', 'Welcome to Codeusingjava')
}