Jenkins interview QA.txt

1  * Explain CI/CD  -- answer from rangaswamy sir
	As soon as developer pushes code to github. Jenkins pipeline job will get triggered, it has three stages, Build, Deploy and test stages.
	In build stage, It will pull source code from github, compiles it and generates binary. Once build stage is success, deploy stage will get triggered
	It will deploy war file tom tomcat server and run BVT. Next,test stage will get triggered, it runs test cases given by test team. 
	if there are any test failures will be taken care by testing team. if there are any integration issues , it will be taken care by dev team.
									
									(OR)
									
	As soon as a developer pushes the code, the code is reviewed by reviewer {Gerrit tool can be used to perform the code review} and then commit is performed, once a new commit occurs, it triggers a Jenkins job.
	Jenkins job consists of mainly 3 stages: Build, Deploy and Test stage
	A webhook tells the CI/CD tool which commit triggers the pipeline, which checks out the source code at the appropriate commit point 
	Build stage à CI/CD tool needs a build tool ( Maven (or) Gradel ), here it will pull the source code from GitHub, compiles it and generates binary, once build stage is success , Deploy stage is triggered 
	Deploy state à It will deploy a war file (web archive file) from tomcat server and run BVT (build verification test) 
	Once BVT is successful, it will then move on to next phase, Test phase
	Test Phase à Here test cases are run as provided by test team (sonarcube is used to validate the quality of the code) 
		If any test failures then it will be checked by testing team, if there are any integration issue, it will be checked by development team 
	Post which artifacts are passed into JFrog artifatory, from there UAT (User acceptance test) is performed, Selenium (or) cucumber can be used to perform the acceptance test.
	
	
2  * How u setup cicd for these different features like u maintain separate jobs for separate feature branches 
		Pipeline Job - jenkins file, write groovy code 
3  * 	1 feature has 50 components how u test that in ur pipeline
		Don't know 

4  * Declarative pipeline? What all the components in it ?
		Pipeline script with SCM
			Pipeline block
				Agent 
				Stages 
                                Stage
                                Steps
5  * Shared Libraries ?
	Jenkins shared library is the concept of having common pipeline code in the version control system that can be used by any number of pipelines just by referring it. 
	Eg – if we have 10 java micro services pipelines the maven build step will be duplicated in all 10 pipelines. On addition of new services, we have to copy paste pipeline code again. If we want to change some parameter we will need to do it in all the pipelines manually. 
	When we use the shared library all the common code is kept there and if we update the code there it will appear in all the 10 pipelines. 
	Jenkins shared library
	1. vars – This directory holds all the global shared library code that can be called from a pipeline. It has all the library files with .groovy extn.
	2. src – It’s a regular java source directory. It is added to the class path during every script compilation. Here we can add the custom groovy code to extend the shared library code.
	3. Resources – all the non-groovy files required for the pipeline can be managed from here. Like jenkinsfile, xml etc. 
	 
6  * When to use free style and pipeline job
	Free style job -- for Single purpose project 
	Pipeline job - To run multiple tasks which are independent/dependent in an automated way 
	
7  * Is it possible that one stage fails and continue the execution to next stage ?
	Option present in Build trigger 
		Build after other projects are built 
		
		 
8  * Write a jenkinsfile which pull the code from git repo and push the jar file to AWS S3?
         (This jenkins file shd work on all environments)

10 * In Jenkins, do you know how to write custom functions in groovy?
		Yes -- pipeline block (agents, stages) -- need to practice 

16 * sonarqube integration
	Qualitygate plugin 

17 * what are the jenkins plugin have you used
	Ssh, parameterized, gearman, maven, github, sonarcube, blueocean 
	Also explain why these plugins are used
		Gearman -  Creates a backup jenkins prod server, so when primary server is down, jenkins services are available via secondary server
		Maven - to integrate builds
		Sonarcube - To integrate testing of code 
		BlueOcean - Integrate dashboard, which allows us to create a pipeline and see through it 

19 * webhooks
		It is a mechanism to automatically trigger the build of a jenkins project upon a commit is pushed in a Git repository
		Need to make sure that we have GitHub plugin installed on Jenkins server
		On Project --> Source Code Management --> select Git --> Give Repository URL 
		Enable "GItHub hook trigger for GITScm Polling" and "Poll SCM"
		On GitHUb --> Settings --> WebHook--> Add webhook --> Payload URL  (your repo link)--> Content type 'application/json' --> which even should trigger this webhook 'Just the push even' --> add webhook 

21  how to send email notification to jenkins

		 Dashboard --> Manage Jenkins --> Configure System --> Extended E-mail Notification
		Maven Build command in java - DO not know 
			We have to run "maven clean package" from where ever we have our project/files but after that steps are longer and need to be practiced and done to explain
	
21 * how to take backup of jenkinfile
	Clone the Jenkins home directory/installation folder and then push to GitHub repository 

23 * How you schedule builds
	Build Trigger periodically 

24 * How you have integrated each tool in CiCd explain configuration
	Yes, Docker, Sonarcube, BlueOcean, TinyBackup 

25 * Explain jenkinsfile
		File containing declarative script in groovy 
		This file contains the configuration to run the pipeline 
		Script is written within the pipeline block 

 36 * Pipeline with stage 1 n stage2, calculate a value of a variable in stage 1 and pass that value in stage2. 
	Declarative script in groovy
	Example script:: 
		pipeline {
		    agent 
		    environment {
		        DISABLE_AUTH = 'true'
		        DB_ENGINE    = 'sqlite'
		    }
		
		    stages {
		        stage('Build') {
		            steps {
		                echo "Database engine is ${DB_ENGINE}"
		                echo "DISABLE_AUTH is ${DISABLE_AUTH}"
		                sh 'printenv'
		            }
		        }
		    }
		}
		
37 * how can i share the value btn two stages in pipeline?
	Using Declarative script in groovy 
	Example script::
		pipeline {
		    agent 
		    environment {
		        DISABLE_AUTH = 'true'
		        DB_ENGINE    = 'sqlite'
		    }
		
		    stages {
		        stage('Build') {
		            steps {
		                echo "Database engine is ${DB_ENGINE}"
		                echo "DISABLE_AUTH is ${DISABLE_AUTH}"
		                sh 'printenv'
		            }
		        }
		    }
		}
		
38 * Have you created any pipeline and type of pipeline ?
	Yes, explain Pipeline job , creation of pipeline job 
	Pipeline --> pipeline script  and Pipeline script with SCM 
	Also give example declarative script (or) pipeline script 

39 * Explain about the diff stages of pipeline
		Explain about Build, Deploy, Test

40 * Which artifactory are you using ?
	Jfrog artifactory -- Need to collect info on Jfrog 

41 * Explain about agents ?
	Agents define the execution scope of the stage
			(or)
	specifies where the entire Pipeline, or a specific stage, will execute in the Jenkins environment depending on where the agent section is placed
	
42 * Have you created dynamic agents
	Need to check, if it is similar to Agents any (or) none 

43 * Jenkins Code as a Service?
	Using pipeline script with SCM --> Jenkins file in groovy script, this is what Jenkins Code as a Service will be 

45 * If you want to write something new thing in Declarative script which you don’t know, how you will be doing it?
	We would go to pipeline syntax --> Snippet generator  (or) Declarative Directive Generator 

46 * Feature Flag in CICD
	is a technique that will help you integrate code into a shared repository at least once a day and ship it, even if you haven't finished the feature yet.

58 * U have some issues in applications in Jenkins how will u find out 
		/var/log/jenkins  

60 * Deployment strategies
		Blue-Green deployment
		Canary Deployment 
		Rolling deployment
		Shadow deployment 

63 * what is that you use in Jenkins for ensure 	all the integration part and test part
	Maven for build, Jenkins Pipeline for integration, Sonarcube for integration testing, selenium for blackbox testing (part of UAT) 

64 * what are the plugins you are using for cicd setup in current company
		○ BlueOcean
		○ Gearman
		○ Git integration
		○ GitHub 
		○ Parameterized
		○ Role-based authorization stratergy 
		○ Maven
		○ Quality gates (sonarcube)
		○ Selenium RC and Selenium Builder
		○ docker

65 * what kind of environment you created for Jenkins cicd setup
		○ QA
		○ Dev
		○ UAT
		○ Prod

71 * Parallel block inside stage
	Build and Test are happening parallel in the below pipeline block 
		pipeline {
			agent { label 'master' } 
			stages {
				stage('Both build and test') {
					parallel {
						stage('Build') { 
							steps {
								sh 'sleep 15; echo "This is a Build stage"'
							}
						}
						
						stage('Test'){
							steps {
								sh '''
									sleep 15
									echo "This is a Test stage"
								'''	
								git branch: 'main', url: 'https://github.com/jaintpharsha/devops-jan-22.git'
							}
						}
		
72 * how to send email notification to jenkins
	Post build actions --> Editable email notification 

73 * what is the deployment strategy that is used in ur company and other stratgies that u know?
		Blue-Green deployment
		Canary Deployment 
		Rolling deployment
		Shadow deployment
		
76 * How are u managing the code quality of ur application. 
		Code quality is managed via Sonarcube 

86 * Benefits of Blue green deployment?
		https://www.flagship.io/blue-green-deployment-pros-and-cons/
		Rapid Releasing
		Simple Rollbacks
		Built in disaster recovery
		Load balancing

93 * When to use free style and pipeline job
		Freestyle project à is for more simple tasks, we cannot use freestyle project for multiple jobs and complex tasks 
		Pipeline Project à We use this to create multiple jobs which may/may not be independent to achieve a release in an automated manner
				With pipeline project we have more control, you can choose which stage of the pipeline can be used in which manner 

95 * when there is no internet connection can you install jenkins 
		If you have downloaded the dependencies and the Jenkins installation package, then yes, you can install Jenkins without internet

96 * no backup & installed lot of plugins & jobs. now installed one more plugin and crashed my whole jenkins. now ui is down..how do you uninstall plugins.
             Go to à /var/lib/jenknis/plugin  and then remove the plugin binary ( *.hpi (or)  *.jpi ) and the folder from the location 

97 * difference between freestyle & pipeline job
		Freestyle project à is for more simple tasks, we cannot use freestyle project for multiple jobs and complex tasks 
		Pipeline Project à We use this to create multiple jobs which may/may not be independent to achieve a release in an automated manner
				With pipeline project we have more control, you can choose which stage of the pipeline can be used in which manner 
	
98 * which you can't do in freestyle. which can be done pipeline technical difference
			With pipeline project we have more control, you can choose which stage of the pipeline can be used in which manner 

100* pipeline syntax
		Declarative script in groovy
		Example script:: 
			pipeline {
				agent 
				environment {
					DISABLE_AUTH = 'true'
					DB_ENGINE    = 'sqlite'
				}
			
				stages {
					stage('Build') {
						steps {
							echo "Database engine is ${DB_ENGINE}"
							echo "DISABLE_AUTH is ${DISABLE_AUTH}"
							sh 'printenv'
						}
					}
				}
			}
	
101* which pipeline you are using in your company
		Multibranch pipeline, pipeline script with SCM 


102* custom build of a core plugin
	 -- Question can be rephrased as -- how to install/unisntall plugin without Jenkins GUI
			Stop jenkins process
			Download the .hpi/.jpi plugin and save it to /var/lib/jenkins/plugin folder (or) Jenkins_home directory plugins folder 

103* have you are checked code quality
		Yes, via Sonarcube , by integrating qualitygates plugin on Jenkins

104* process to integrate git with jenkins
		--> Install the GitHUb Plugin, GitHub API, GitHub Client, GitHub BranchSourceCode plugin
		--> Create a Jenkins project 
				Go to--> Source Code Management --> Git 
				Enter --> Repository URL and credentials 

106* whats the use of pom.xml file
		==>  POM.xml is a xml file, which contains the project details along with configuration information which is used by Maven to perform builds
		==> When "maven install" is done, maven creates a dependency tree based on the information from PO.xml and then downloads/compiles all the needed components    into a directory ".m2" under the user's fodler
107* maven build lifecycle
	 
	Maven Lifecycle steps
	----------------------
		Validate -->  If project is correct and has all necessary information 
		
		Compile  -->  Compile the source code of the project 
		
		Test      -->  Test the source code without packaging (or) deploying it, using a unit testing framework 
		
		Package  --> Package the source code into .jar, which is the distributed format
		
		Integration Test --> Testing of various software modules as a group 
		
		Verify --> Check the results of integration testing and ensure quality is met
		
		Install  --> Install the package into local repository 
	
		Deploy  --> Copies final package to remote repository for sharing with other developers done in build env 
		
112* why do we need continuous integration and continuous deployment in jenkins, what are the advantages.
		 CI - You need CI so the developers can get immediate feedback on their code quality and build
		CD - Once the code is build, tested successfully, It can be pushed to the production environment 
		There is a continuous feedback loop on the code builds and testing which is being done
	
113* How to select slaves in jenkins file

		using agent none and assigning the label, so the specific stage can be run on specific agent (slave agent) 
		
115* How webhook triggers
		• Need to make sure that we have GitHub plugin installed on Jenkins server
		• On Project --> Source Code Management --> select Git --> Give Repository URL 
		• Enable "GItHub hook trigger for GITScm Polling" and "Poll SCM"
		 
		• On GitHUb --> Settings --> WebHook--> Add webhook --> Payload URL  (your repo link)/git-webhook --> Content type 'application/json' --> which even should trigger this webhook 'Just the push even' --> add webhook 

 116* How authentication of Jenkins and git is done
	Jenkins authentication 
		○ Matrix based security
		○ Project based matrix authorization stratergy 
		○ Role based authentication/strategy -- need to install plugin for this
		By saving the credentials in Git Credential storage   --> https://www.shellhacks.com/git-config-username-password-store-credentials/
	Git Credentials binding plugin on jenkins 
		Here we can give Git username and password 
117* What kind of credentials used - same as previous question 
		
118* What build tool ? how build happen?
		Build Tools ==>  Maven, Make, Gradel 
		Explain Maven Lifecycle 
			Maven Lifecycle steps
		
				Validate -->  If project is correct and has all necessary information 
				
				Compile  -->  Compile the source code of the project 
				
				Test      -->  Test the source code without packaging (or) deploying it, using a unit testing framework 
				
				Package  --> Package the source code into .jar, which is the distributed format
				
				Integration Test --> Testing of various software modules as a group 
				
				Verify --> Check the results of integration testing and ensure quality is met
				
				Install  --> Install the package into local repository 
				
				Deploy  --> Copies final package to remote repository for sharing with other developers done in build env

                     make---
                                ABC.exe:output.o search.o sort.o input.o
                             gcc -o ABC.exe output.o search.o sort.o input.o
		     output.o:output.c
                             gcc -c output.c
                     search.o:search.c
                             gcc -c search.c
                     sort.o:sort.c
                             gcc -c sort.c
                     input.o:input.c
                             gcc -c input.c      

124* CICD set up
		CI/CD pipeline, Jenkins configuration , Multibranch pipeline/pipeline script with SCM 

125* Difference between CI and CD
		CI - continuous integration 
			Integrating changes from development team without manual intervention and giving immediate feedback to the development team 
		CD -- Continuous Delivery
			Testing the changes immediately post pushing of code by development team 
		CD -- Continuous Deployment
			Deploying to production environment post testing 

126* Branching strategies means git work flows
		 Feature Branching 
		 Releasing branching
		 
131* Tomcat troubleshooting steps
	 Check if the tomcat service is running (or) not
		Sudo systemctl tomcat status 
		Sudo systemctl tomcat start 
	If it fails to start then check the logs
		/var/log/messages
		
133* Where is jenkins set up
	  On-premise (or) Containers (or) Cloud 

138* In maven, explain how you download dependencies
	 "maven build"  --> this command is run, it downloads all the dependency jars into the local repository 
		So basically maven will check pom.xml file and check for the jar file information and then download the dependency to the local repository accordingly 

140* Explain your deployment strategy
	Choose any one and explain in details 
		○ Blue-Green deployment
		○ Canary Deployment 
		○ Rolling deployment
		○ Shadow deployment
		
141* I want two stages to execute at a time in jenkins, can I do that... How?
	Using Jenkins file by utilizing parallel script 
		Example::
		Jenkins Parallel script 
		
		pipeline {
			agent { label 'master' } 
			stages {
				stage('Both build and test') {
					parallel {
						stage('Build') { 
							steps {
								sh 'sleep 15; echo "This is a Build stage"'
							}
						}
						
						stage('Test'){
							steps {
								sh '''
									sleep 15
									echo "This is a Test stage"
								'''	
								git branch: 'main', url: 'https://github.com/jaintpharsha/devops-jan-22.git'
							}
						}
					} 
				}
				stage('Deploy'){
					steps {
						sh '''
							sleep 5
							echo "This is a Deploy stage"
						'''
					}
				}
				
				stage('My-stage'){
					steps {
						sh '''
							sleep 5
							echo "This is a My-stage stage"
						'''
					}
				}	
			}
		}
		
142* I want to select particular version for build, how can i do that during CI CD
		==> Jenkins project # tag build version, we chose the build version from there 
										(or)
		==> Jenkins file, pipeline script, node information 


146* How you configured webhooks, which URL you used there
		Jenkins Payload URL 

149* if your jenkins agents are setup for 20 build capacity, and suddenly 50 builds comes in how will you handle the situation?
		○ Need to install the Amazon EC2 plugin in Jenkins 
		○ Manage Jenkins --> Configure System --> Cloud section --> Add a new cloud button --> Select "Amazon EC2" option  
		 Check the link for further understanding ==> https://plugins.jenkins.io/ec2/ 
		○ So this will provide Jenkins with option of identifying cluster overload and deploy ec2 instances with Jenkins agents on them, once the cluster load is reduced , then it will delete the ec2 instnaces 

153* which instance type u r using for jenkins master, its details
		Amazon ec2 ==>  c4.large, c4.xlarge

156* explain stages in cicd
		Build, Deploy, Test 


158* how your implementing QA in your cicd
		By integrating Sonarcube and selenium in Jenkins
		Installing Quality Gates in sonarcube and also selenium plugins 

161* multibranch pipeline ?
		The Multibranch Pipeline project type enables you to implement different Jenkinsfiles for different branches of the same project.
		In a Multibranch Pipeline project, Jenkins automatically discovers, manages and executes Pipelines for branches which contain a Jenkinsfile in source control.

162* How to setup multiple Java or Maven or Git versions in Jenkins server?
		Manage Jenkins --> Global Tool configuration --> install the tool versions accordingly 



 

============================================Discussed with Harsha sir==================================================




1) Jenkins is building on dev branch and someone else is pushing the code, but the build is in progress.  If someone pushes the code, it triggers another build, so what will u do to stop the parallel build?
        Declarative Script
        pipeline {
            options {
                disableConcurrentBuilds()
            }
        }

    Scripted 
        node {
          properties([disableConcurrentBuilds()])
        }

2) How do you disable it in groovy script?(continue from above question)

       Declarative Script
        pipeline {
            options {
                disableConcurrentBuilds()
            }
        }

    Scripted 
        node {
          properties([disableConcurrentBuilds()])
        }                  

  ---by default groovy is serial execution 

3) How frequently u release a new feature ?  -- confirm the answer 
		
        Based on the application/project
		There are major release and minor release 
			Major updates may be quarterly (or) yearly depending on the application and project that we are associated with
		           For test environment we release it frequently and it is deployed immediate, since we have a pipeline created

4) when we use process of creating multibranch pipeline in jenkins ?
                
                    its depending upon the project most of the cases we won't use it
                     if it's require to build for all banches for every commit to all baranches then we use it.

		
5) how do you use function in groovy script?

  @Library('Shared library') _
  greetUser 'USERNAME' 'DESIG'
     
6) how will set the quality gates in sonar qube and how will you check quality of source code
       go for any video in youtube for better clarification--jfrog xray,sonarqube,sonar runner,sonar scanner

         https://www.youtube.com/watch?v=Spzk1lrCgNY

7) How you will do insights and analysis of your CICD?
     
       will identify the tools stack (or) technology--ex:maven
       communicate with dev team,will get to know what we have to buld so that
       we can decide how many stages are required including test automation.

8) I have a jenkins pipeline where sonarqube is integrated with quality gates. But if the code doesnt passes through quality gates how will you fail the build and stop it     from creating artifacts.?

               https://www.youtube.com/watch?v=Spzk1lrCgNY

9) explain your Jenkins setup like how many slaves you are maintaining

Multi-master cluster 
		Minimum 3 master 
	We setup via either AWS (or) Kubernetes 
	Based on available computer resources,we can have 12 slaves 
	In our company we have around 400-500 builds depending upon the teams, we have around 10 slaves 
	For testing builds, where we can go upto 800 builds, we can stretch our slaves upto 12, also we do have process to have slaves spinned up when required
 
10) Real life scenarios on Canary deployment?
      harsha sir will explain in k8's

11) What is the default deployment strategy?
              k8's
     
12) Is it possible that one stage fails and continue the execution to next stage ?
         yes,using try catch block

        stage('build'){
                     steps {
                           sh  echo'if this build will fails'
                    }
                 }
   stage('NAME') {
            steps {
                catchError(busildResult: 'SUCCESS', stageResult: 'FAILURE') {
                    sh "exit 1"
                }
            }
        }
      

13) jenkins build failures
      
14) how to deploy an application from jenkins to k8s  -- Kubernetes topic 

                helm charts

15) CICD jenkins have you build any pipeline , in process approval in jenkins. detect that failure in deployment time and commands to use to reverse the build.
              yes,if the build fails will deploy previous build(roll out)

16) Jenkins is on premise ?
            No,we are using AWS so jenkins server runs on AWS.
17) I want to select particular version for build, how can i do that during CI CD ? -- confirm below answer
 
                      use parameterised build (or) job
		
18) which tests you perform in ci cd ? (or)  what are the diffrent type of test u do in cicd? -- confirm below answer 
		Integration test, sanity test, UAT etc…

19) how you have deployed to production explain the procedure?
      once ECAB apporves we have a job which is not automated,we manually run the job for prod env
      
20)  How you automate complete cicd ?  -- Maybe after Kubernetes, please confirm
      
21)Pipeline with stage 1 n stage2, calculate a value of a variable in stage 1 and pass that value in stage2?
    pipeline {
    agent {
        label '!windows'
    }

    environment {
        DISABLE_AUTH = 'true'
        DB_ENGINE    = 'sqlite'
    }

    stages {
        stage('Build') {
            steps {
                echo "Database engine is ${DB_ENGINE}"
                echo "DISABLE_AUTH is ${DISABLE_AUTH}"
                sh 'printenv'
            }
        }
    }
}