Jenkins Interview Questions | Jenkins Interview Questions And Answers | DevOps Tools | Simplilearn

2. Continuous Integration - Jenkins

3. 1 Explain master - slave architecture of Jenkins. • Jenkins master pulls the code from the remote GitHub repository every time there is a code commit • It distributes the workload to all the Jenkins slaves • On request from Jenkins master, the slaves carry out builds and tests and produce test reports

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5. 2 What is a Jenkinsfile? It is a text file that contains the definition of a Jenkins pipeline and is checked into source control repository There is a single source of truth for the pipeline which can be viewed and edited Allows code review and iteration on the pipeline Permits audit trail for the pipeline What it does?

6. 3 Which of the following commands runs Jenkins from the command line? (a) java –jar Jenkins.war (b) java –war Jenkins.jar (c) java –jar Jenkins.jar (d) java –war Jenkins.war

7. 4 What concepts are key aspects of Jenkins pipeline? Pipeline: User-defined model of a CD pipeline. Pipeline’s code defines entire build process, that includes building, testing and delivering an application Node: A machine which is part of Jenkins environment capable of executing a pipeline Pipeline key aspects Stage: Defines a conceptually distinct subset of tasks performed through the entire pipeline (build, test, deploy stages) Step: A single task that tells Jenkins what to do at a particular point in time

8. 5 Which file is used to define dependency in maven? (a) build.xml (b) pom.xml (c) dependency.xml (d) version.xml

9. 6 Explain the two types of pipeline in Jenkins along with their syntax. Jenkins provides 2 ways of developing a pipeline code: Scripted and Declarative Scripted Pipeline: It is based on Groovy script as their Domain Specific Language. One or more node blocks does the core work throughout the entire pipeline Execute this pipeline or any of its stages on any available agent Jenkinsfile (Scripted Pipeline) node { stage(‘Build’) { // } stage(‘Test’) { // } stage(‘Deploy’) { // } } 1 1 Defines the Build stage 2 2 3 Performs steps related to Build stage 3 4 Defines the Test stage 4 5 Performs steps related to Test stage 5 6 7 Defines the Deploy stage 6 Performs steps related to Deploy stage 7

10. 6 Explain the two types of pipeline in Jenkins along with their syntax. Jenkins provides 2 ways of developing a pipeline code: Scripted and Declarative Declarative Pipeline: It provides a simple and friendly syntax to define a pipeline. Here, pipeline block defines the work done throughout the pipeline Jenkinsfile (Declarative Pipeline) pipeline { agent any stages { stage(‘Build’) { steps { // } } stage(‘Test’) { steps { // } } stage(‘Deploy’) { steps { // } } } } 1 Execute this pipeline or any of its stages on any available agent 1 2 Defines the Build stage 2 3 Performs steps related to Build stage 3 Defines the Test stage 4 4 Performs steps related to Test stage 5 5 Defines the Deploy stage 6 6 Performs steps related to Deploy stage 7 7

11. 7 How do you create a backup and copy files in Jenkins? To create a backup, periodically backup your JENKINS_HOME directory periodically JENKINS_HOME files Build jobs configurations JENKINS_HOME contains Slave node configurations Build history To create a back-up of your Jenkins setup, copy JENKINS_HOME directory. You can also copy a job directory to clone or replicate a job or rename the directory

12. 8 How can you copy Jenkins from one server to another? Copy the jobs directory from the old server to the new one copy Jobs directory (old server) Jobs directory (new server) Following are the ways to do it: • Move a job from one installation of Jenkins to another by copying the corresponding job directory • Create a copy of an existing job by making a clone of a job directory by a different name • Rename an existing job by renaming a directory

13. 9 Name three security mechanisms Jenkins uses to authenticate users. 1 Jenkins can be configured to employ the authentication mechanism used by the application server upon which it is deployed Jenkins uses an internal database to store user data and credentials 2 Lightweight Directory Access Protocol (LDAP) server can be used by Jenkins to authenticate users 3

14. 10 How to deploy a custom build of a core plugin? Steps to deploy a custom build of a core plugin • Copy the .hpifile to $JENKINS_HOME/plugins • Remove the plugin’s development directory • Create an empty file called <plugin>.hpi.pinned • Restart Jenkins and use your custom build of a core plugin

15. 11 How can you temporarily turn off Jenkins security if the administrative users have locked themselves out of the admin console? contains a file JENKINS_HOME folder Config.xml • When security is enabled, Config file contains an XML element named useSecurity that will be set to true • By changing this setting to false, security will be disabled the next time Jenkins is restarted

16. 12 What are the ways in which build can be scheduled/run in Jenkins? • By source code management commits • After completion of other builds • Scheduled to run at specified time • Manual build requests

17. 13 Mention the commands that you can use to restart Jenkins manually. Two ways to manually restart Jenkins: Forces a restart without waiting for builds to complete (Jenkins_url)/restart Allows all running builds to complete before it restarts (Jenkins_url)/safeRestart