Jenkins Interview Question

#90daysofdevopsChallenge

#day29

1. What’s the difference between continuous integration, continuous delivery, and continuous deployment?

   Continuous Integration: When the developer or development team merges the code in a common repository and performs some basic testing for code scan that process is called Continuous Integration.

   Continuous Delivery: After the continuous integration process, if we also add steps to deploy it in a testing environment running some dev-test and QA test, until this step, the process is called Continuous Delivery.

   Continuous Deployment: After the continuous Integration and Delivery process, if we add the stage of production deployment, It will be called continuous deployment.

2. Benefits of CI/CD.

   a) Avoid Branching and Merge Code Daily: Developers are required to merge code daily from the local branch to the main branch unit. This reduces the complications of merging errors and conflicts.

   b)Higher Efficiency or Increased Productivity: This is one of the best advantages of the CI/CD pipeline.

   c) Reducing the risk of Defects: It is very costly to find and resolve defects in deployment. so CI/CD helps to test code multiple times before the deployment process.

   d) Faster Product Delivery: CI/CD is less time-consuming due to automated processes. With a smooth CI/CD workflow, multiple daily releases can become a reality.

   e) Log generation: If something is not right, you need to figure it out or troubleshoot, in such cases, Log plays a vital role in observability.

3. What is meant by CI-CD?

   CI-CD stands for Continuous Integeration-Continuous Deployment. From the stage of developing a code by the developer to deploying the code successfully end to end, the whole process is called CI-CD. The whole process is automated.

4. What is Jenkins Pipeline?

   Jenkins-pipeline is a collection of plugins that are used to allow the creation of simple to complex build pipelines as code. It is a powerful way to automate the build, test, and deployment process of software applications.

   In Jenkins pipeline written in Groovy-based domain-specific language which is easy to understand for both developers and non-developers like.

5. How do you configure the job in Jenkins?

   To create a job in Jenkins, required to perform some tasks:

   a) Go to Jenkins web browser and Log in to Jenkins.

   b) Click on "New items" and then click on "New Jobs".

   c) Give a Name to the job and choose a Job type like Freestyle Projects, Maven Projects, Pipeline Projects, etc.

   d) After Configuring the job click on the "Save" buttons to save the job.

   e) You can now build the job by clicking on the "Build Now" Button in the left navigation menu.

6. Where do you find errors in Jenkins?

   You can find errors in Jenkins in multiple places:

   a) Build Console Output: The build console output provides log-in detail, including any errors or warming that may have occurred.

   b) Pipeline Visualization: If you are using Jenkins Pipelines, the pipeline visualization provides a graphical representation of the build process. Any errors or failures in the pipeline will be indicated by a red dot or other visual cases.

   c) Jenkins logs: Jenkins generates log files to resolve the errors. these log files are present on the "Manage Jankins" > "System Log" page.

7. In Jenkins how can you find log files?

   a) In Jenkins log files can be found at Manage Jenkins > System Log.

   b) Click on the build number > Console Output.

   c) If you need access to the logs outside of the Jenkins UI, then it will be present in the JENKINS_HOME/logs directory on the Jenkins Server.

8. Jenkins workflow and write a script for this workflow?

   Jenkins workflow is called as Jenkins pipeline and provides a suite of plugins that allows defining Jenkins continuous delivery process in Jenkins pipeline using code as a script.

    pipeline {
        agent any 
        stages {
            stage('Build') { 
                steps {
                    // 
                }
            }
            stage('Test') { 
                steps {
                    // 
                }
            }
            stage('Deploy') { 
                steps {
                    // 
                }
            }
        }
    }
   

9. How to create a continuous deployment in Jenkins?

   Step 1: Open Jenkins on Browser and Login to Jenkins

   Step 2: Click on New Item, Choose either a Freestyle project or a pipeline project and give it a name.

   Step 3: Connect your source code management tool, Git, to Jenkins and Configure the repository and credentials.

   Step 4: Write the pipeline to deploy your application

   Step 5: Save the Configuration and Run the pipeline to test it.

10. Why do we use a pipeline in Jenkins?

    Pipelines help to improve the speed, quality, and reliability of software development. It simplifies the software delivery process by automating the build, test, and deployment steps.

    The main benefit of using pipelines, provide an automated process and a clear, organized approach to delivering software.

11. Is Only Jenkins enough for automation?

    Jenkins is enough for automation but only for small projects. and the requirement for other tools depends on the organization or project.

    Jenkins for automation include:

    a) Version Control System (Git, Gitlab, GitHub)

    b) Test Automation Frameworks

    c) Deployment tools

    d) Containerization Tools

    e) Monitoring and Logging tools.

12. How will you handle Secret?

    Jenkins handles Secret in two ways:

    a) Jenkins Credentials

    b) Environment Variables

13. Explain different stages in CI-CD setup.

    In the whole setup of CI-CD there are multiple steps:

    a) Code Development: In this Stage, Developers write the code and commit it to a version control system like Git.

    b) Code Build: In this stage, Jenkins or another CI tool is used to build the code, compile it, and run tests to ensure that the code is working as expected.

    c) Code Test: It is the testing stage, during this stage various testing techniques such as unit testing, integrating testing, and functional testing to ensure that it meets the required quality standards.

    d) Code Deploy: In the deployment stage, deploy code on a different environment for further testing or to the production environment if all the testing is done successfully.

14. Name some of the plugins in Jenkins.

    Jenkins provides multiple plugins to add extra features and functionality.

    a) Git Plugin for Version Control Integration

    b) Docker plugin to perform the tasks related to Docker such as image build and image push on the repository.

    c) Pipeline plugin for Continuous Integration and delivery.

    d) Artifactory plugin for managing binary artifacts.

    e) Blue Ocean plugin for a modern user interface.

    f) JUnit plugin for testing code.

    g) Slack plugin used for communication and collaboration.

    h) EC2 Plugin for dynamic provisioning of build agents.

    i) SonarQube plugin for code analysis.

    j) Ant plugin for building code.

15. What is Jenkins Groovy DSL, and how is it used in Jenkins pipelines?

    Jenkins Groovy DSL (Domain Specific Language) refers to the scripting language that is used to define the Jenkins pipeline as code. Jenkins pipeline allows you to define the jobs in Groovy DSL which gives you more flexibility and more control over your build and deployment process.

16. What is the purpose of the Jenkins workspace?

    In Jenkins, the workspace refers to the directory on the agent (or node) where Jenkins jobs are executed. Each job in Jenkins has its dedicated workspace, and this workspace is used to store and perform all the operations related to that specific job, such as checking out source code, building, testing, and producing artifacts.

17. How can you archive artifacts in Jenkins, and why is it important?

    Archiving artifacts in Jenkins is the process of preserving and storing important files or artifacts generated during the build process. Jenkins provides a built-in feature to archive artifacts, and this can be configured within the Jenkins job configuration.

18. Explain the concept of Jenkins slave nodes and when you would use them.

    In Jenkins, slave nodes (also known as build agents or worker nodes) are additional machines that are configured to offload and distribute the execution of Jenkins jobs from the master node. The master node manages the overall Jenkins system, and by using slave nodes, you can distribute the workload across multiple machines, enabling parallel execution of jobs.

19. What is the purpose of the Jenkins file and how is it different from traditional build scripts?

    The Jenkins file is a key concept in Jenkins Pipelines, and it serves as a text-based configuration file that defines the entire build, test, and deployment process for a Jenkins Pipeline job. It represents the evolution of the traditional approach of using graphical interfaces or separate build scripts for defining Jenkins jobs.

20. How can you back up and restore Jenkins configurations and jobs?

    Backing up and restoring Jenkins configurations and jobs is crucial for ensuring the stability and continuity of your Jenkins instance. This process helps you recover from hardware failures, accidental changes, or other issues that may affect the Jenkins environment.

    a) The Jenkins home directory is typically located at a path specified during Jenkins installation (e.g., /var/jenkins_home).

    b) Jenkins system configurations, including global tool configurations, security settings, and plugin configurations, are stored in files within the JENKINS_HOME directory.

    c) To restore Jenkins, copy the entire Jenkins home directory back to its original location on the new or repaired Jenkins server.

    d) Ensure the correct permissions for files and directories.

The Next Article will explore the Container Orchestration tool Kubernetes.

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