Top 80+ Jenkins Interview Questions and Answers

Answer:

Jenkins refers to an open-source tool with a plugin built for continuous integration. Its central functionality is to initiate & monitor a build system if changes occur or to keep track of the version control system. It monitors the entire process & provides notifications & reports to alert.

Answer:

Jenkins is widely used for the following purposes:

• Testers and developers use Jenkins to detect defects in the entire lifecycle of software development & automate the testing of builds.
• Developers use Jenkins to continuously monitor code in real-time & integrate change into the build.
• Jenkins is the best fit for building a CI/CD pipeline due to its plugin capabilities & simple-to-use nature.

Answer:

Jenkins comes with the following key features:

• Free & open source.
• Easy installation on different operating systems.
• It can build pipeline support.
• It offers a workflow plugin.
• Jenkins tests the harness built around the JUnit.
• It provides easy upgrades.
• It has a rapid release cycle.
• It has an easy configuration setup.
• Jenkins can be extensible with the use of third-party plugins.

Answer:

Here are some advantages of Jenkins :

• It enables bug tracking at an early stage of development.
• Jenkins provides a large no. of plugin support.
• Through Jenkins, build failures get cached at the integration stage.
• For each code commit change, an automatic build report notification is generated.
• It is integrated with the LDAP mail server to notify developers regarding build report failure or success.
• It achieves continuous integration or CI agile & test-driven development.
• With simple steps, it also automates the Maven release project.

Answer:

Follow these steps to achieve continuous integration:

• All developers should commit their source code changes to a shared Git repository.
• The Jenkins server checks the shared Git repository at the specified intervals; thereby, detected changes are taken into the build.
• The build results & test results are shared with the developers.
• The built app is displayed on the test server, such as Selenium & automated tests are run.
• The clean & tested build is then deployed to the production server.

Answer:

1. GitLab- GitLab CI/CD tool is a robust alternative to Jenkins. It is an open-source interface used to apply all the continuous methods, such as integration, deployment, & delivery to your project without any third-party application. It renders a user-friendly interface with some distributed version control services.
   Below are a few features of GitLab that make it the best alternative to Jenkins:

• GitLab is an open-source tool, just like Jenkins.
• It allows you to test your build in parallel, thus reducing time.
• It enables docker integration and helps in automating app delivery.
• It offers better support.
• Atlassian Bamboo- Bamboo is a product of Atlassian useful for continuous integration, deployment & development. It runs tests, builds, & integrates with JIRA to update issues, commits & connect the test results for end-to-end visibility within the team. It also supports multiple technologies such as Amazon S3 buckets, Mercurial, Git, AWS, SVN, etc.
  Here are some key features of Bamboo:
  • It helps to run parallel batch tests.
  • It streamlines integration with Fisheye, JIRA, & BitBucket.
  • It can be set up effortlessly.
• CircleCI- It is a flexible tool that is easy to maintain & can run in any environment. It provides the following features:
  • Integration with GitHub Enterprise, GitHub, & Bitbucket.
  • CircleCI splits tests amongst multiple containers, thus reducing build time.
  • It provides SSH support so users can access the VM through SSH & run commands.
  • It is easy to maintain as it supports automatic upgrades.
• TeamCity- It is also called an “Intelligent CI server” as it is easy to use & integrate. TeamCity provides different installation packages for different OS. It is a potent tool developed by JetBrains, which enables it to run & build tests even before the changes are committed, hence keeping the code clean.
  Some features that make TeamCity one of the best Jenkins alternatives:
  • It is a well-documented tool that provides easy installation.
  • It offers easy integration with some tools like JIRA, Docker, etc.
  • TeamCity renders a well-defined API available for extension.
• Travis CI- It is a continuous testing & integration CI/CD tool. It is free to use for open-source projects & supports seamless integration with GitHub. It also supports over 20 programming languages, such as Python, PHP, Node.js, and Docker.
  Some key features of Travis CI include:
  • It is easy to set up with extensive user community support.
  • It does not allow any project to merge before tests are successfully passed.
  • You can customize the build environment as per your needs.
• BuildMaster- BuildMaster is one of the best alternatives to Jenkins, and it provides continuous integration on different platforms. It helps you manage your applications & provides a hassle-free app deployment to an environment. Besides, it doesn’t need extensive expertise to set up the pipelines.
  Some of the features of BuildMaster include:
  • It helps to create release management platforms that can be easily managed by oneself.
  • It provides automated gates that prevent the release of untested software.
• Bitrise- It comes as a PaaS (platform as a service) for continuous delivery & integration in mobile apps. Each build runs on its VM at the end of the build. The data is scrapped. It provides a free plan & enables integration with services like HockeyApp, Slack, etc.
  Bitrise provides features as follows:
  • It helps to deliver applications with no manual intervention.
  • Bitrise integrates with the major third-party deployment & testing services.
  • It enables quick setup, having service integration with several services.
• Spinnaker- Spinnaker refers to an open-source platform built by Netflix for continuous delivery. It provides integration with major cloud players. It supports various hosting technologies such as Kubernetes, Docker, etc.
  Key features of Spinnaker are :
  • It is a flexible & powerful pipeline management system.
  • It offers integrations to major cloud providers such as AWS, Oracle Cloud, Google Cloud, & Microsoft Azure.
• UrbanCode- UrbanCode is an IBM product. It provides continuous integration with multiple features like traceability, visibility, & auditing bundles in a single package. It allows faster delivery of applications. Regardless of the environment, you can quickly deploy apps to the cloud, data centers, or virtual environments with no error.
  Here are some features that make UrbanCode a preferred alternative to Jenkins:
  • It reduces deployment errors.
  • The drag & drop feature of UrbanCode makes it convenient to use.
  • It increases the frequency of delivering applications.
• Buddy- Also known as Buddy Works, it is a continuous integration & delivery software with an interactive UI. It helps to test, deploy, & build apps quickly. You can get your CI/CD pipeline running in a few minutes configurations.
  It provides features like :
  • Buddy offers on-premise solutions.
  • It provides support for multiple languages.
  • One can customize the build & test environment as required.

Answer:

DevOps refers to a software development practice that combines IT operations (Ops) & software development (Dev) to simplify the entire development lifecycle by constantly delivering features, fixes, builds, & updates. Jenkins plays a significant role as it helps in this integration by automating the build & deployment process.

Answer:

Here are the minimum system requirements to install Jenkins:

• Java 8
• Web browser
• 256MB of RAM
• 1 GB of drive space

Answer:

To install Jenkins, you need to follow these simple steps:

• Install Java Version 8: Jenkins is a Java-based application; thus, Java is a must.
• Install Apache Tomcat Version 9- Tomcat is important to deploy the Jenkins war file.
• Download Jenkins War File- This war is a must to install Jenkins.
• Deploy Jenkins war File- You should deploy war files by using Tomcat to run Jenkins.
• Install Suggested Plugins-Install a list of plugins as suggested by Jenkins.

Answer:

• Gits
• Join
• Maven 2
• Amazon EC2
• Copy artifact
• Green Balls
• HTML Publisher

Answer:

Apache Groovy is a language specifically designed for the Java platform. It is a native scripting language for Jenkins. Groovy-based plugins enhance Jenkins with great interfaces & build dynamic and consistent reports.

Answer:

Jenkins supports these Source Code Management or SCM tools:

• SVN
• ClearCase
• CVS
• Git
• AccuRev
• Perforce
• RTC
• Mercurial

Answer:

A build job or job implies a task in the entire build process. It could be running unit tests, deploying the apps to a web server, compiling the source code, etc.

Answer:

The pipeline in Jenkins represents the continuous integration & delivery of all the jobs in the SDLC & DevOps lifecycle. It is a set of plugins that supports the implementation & integration of continuous delivery pipelines into Jenkins. The Jenkins pipeline solves various problems like the maintenance of thousands of jobs & their deployments.

Answer:

There are three types of pipelines in Jenkins:

• CI/CD pipeline (Continuous Integration Continuous Delivery);
• Scripted pipeline, and,
• Declarative pipeline

Answer:

Jenkins uses the Cron syntax that is represented with five asterisks, each separated by a space. The syntax is as follows:[minutes] [hours] [day of the month] [month] [day of the week].

Answer:

The following steps can help you Build jobs in Jenkins:

• Step 1: Go to the Jenkins dashboard & click on the New Item.
• Step 2: Enter the Item’s name, then choose the ‘Freestyle project option.’
• Step 3: Specify the job details.
• Step 4: Now, specify the location of the files that need to be built.
• Step 5: In case your repository is hosted on GitHub, enter the URL of that repository (if needed).
• Step 6: Build section & click on the “Add build step.”
• Step 7: In the command window, enter the below commands & click on the Save button. ( Javac HelloWorld.java  Java HelloWorld)
• Step 8: Click the Build Now option to ensure you have successfully defined the job.
• Step 9: Once you schedule the Build, it will run.
• Step 10: Click on the “Console Output link” to see the details of the Build.

Answer:

The below steps define the process of configuring third-party tools in Jenkins:

• Install a third-party software;
• Install a Jenkins plugin that supports the third-party tool;
• Now, configure the third-party tool from the Manage Jenkins section;
• Your plugin is now ready to use.

Answer:

There are three ways in which Jenkin authenticates the users:

• The default way is to store user credentials & data in the internal database.
• Configure Jenkins to utilize the authentication mechanism defined by the app server on which it is deployed.
• Configure Jenkins to authenticate against the LDAP server.

Answer:

• Jenkins is an open-source tool, whereas Bamboo is a commercial tool.
• A massive global community supports Jenkins. In contrast, Bamboo has a dedicated development team.
• Jenkins is less user-friendly as compared to Bamboo.
• Jenkins has various plugins to perform different functions. On the other hand, Bamboo has many built-in features along with plugins available on the Atlassian marketplace.