Interview questions for Jenkins

Just commit changes to the SCR (Source Code Repository) and Jenkins can automate the rest of the process for you with the help of plugins. So that makes it a very important tool in Devops Certification Training. There is a high possibility that you encounter many Jenkins questions if you go for a Develops job interview.

1. What is Jenkins?

Jenkins is an open-source automation tool written in Java with plugins built for Continuous Integration purposes. Jenkins is used to build and test your software projects continuously making it easier for developers to integrate changes to the project, and making it easier for users to obtain a fresh build. It also allows you to continuously deliver your software by integrating with a large number of testing and deployment technologies.

2. Define the process of Jenkins?

• First, a developer commits the code to the source code repository. Meanwhile, the Jenkins server checks the repository at regular intervals for changes.
• Soon after a commit occurs, the Jenkins server detects the changes that have occurred in the source code repository. Jenkins will pull those changes and will start preparing a new build.
• If the build fails, then the concerned team will be notified.
• If the build is successful, then Jenkins deploys the build in the test server.
• After testing, Jenkins generates feedback and then notifies the developers about the build and test results.
• It will continue to check the source code repository for changes made in the source code and the whole process keeps on repeating.

3. What is the difference between Hudson and Jenkins?

There is no difference between Hudson and Jenkins. Hudson was the former name of Jenkins, after going through several issues the name was changed to Jenkins.

4. Mention some of the important plugins in Jenkins?

Plugins in Jenkins includes:
• Gits
• Maven 2 Project
• HTML Publisher
• Copy Artcraft
• Join
• Green Balls
• Amazon EC2

5. What are the pre-requisites for using Jenkins?

The answer to this is pretty straightforward. To use Jenkins you require:
• A source code repository which is accessible, for instance, a Git repository.
• A working build script, e.g., a Maven script, checked into the repository.

6. What is Continuous Integration in Jenkins?

Continuous integration is the process of continuously checking-in the developer’s code into a version control system and triggering the build to check and identify bugs in the written code.
This is a very quick process and also gives them a chance to fix the bugs. Jenkins is one such continuous integration tool.
In software development, multiple developers work on different software modules. While performing integration testing all the modules are being integrated together. It is considered as the development practice to integrate the code into the source repository
Whenever the programmer/developer makes any change to the current code, then it automatically
gets integrated with the system running on the tester’s machine and makes the testing task easy and speedy for the system testers.
Continuous Integration comprises of:
• Development and Compilation
• Database Integration
• Unit Testing
• Production Deployment
• Code Labeling
• Functional Testing
• Generating and Analyzing Reports

7. What is the relation between Hudson and Jenkins?

You can just say Hudson was the earlier name and version of current Jenkins. After some issues, they renamed the project from Hudson to Jenkins.
Mention some of the useful plugins in Jenkins
Below I have mentioned some important Plugins:
• Maven 2 project
• Git
• Amazon EC2
• HTML publisher
• Copy artifact
• Join
• Green Balls

8. Mention some of the useful plugins in Jenkin?

Some of the important plugins in Jenkin includes
• Maven 2 project
• Amazon EC2
• HTML publisher
• Copy artifact
• Join
• Green Balls

9. Explain how you can deploy a custom build of a core plugin?

To deploy a custom field of a core plugin, you have to do following things
• Stop Jenkins
• Copy the custom HPI to $Jenkins_Home/plugins
• Delete the previously expanded plugin directory
• Make an empty file called <plugin>.hpi.pinned
• Start Jenkins

10. Mention some of the useful plugins in Jenkin?

Some of the important plugins in Jenkin includes
• Maven 2 project
• Amazon EC2
• HTML publisher
• Copy artifact
• Join
• Green Balls

11. How to setup a Jenkins job?

First, we need to create a Jenkins job by going to the Jenkins top page and then selecting a ‘New Job’ and building a freestyle software project. Some of the elements of a freestyle project include the following:
• We need a CVS or a subversion where our source code will reside.
• When Jenkins performs the builds, we will need the optional triggers.
• We need a build script like a Maven or Ant where the script is actually built.

12. Explain the Jenkins tool?

Jenkins can be thought of as an open-source automation tool that is used for continuous integration. With Jenkins, we will be able to continuously test our software projects so that developers will be able to integrate the changes to the project. We can also integrate this automation tool with a large number of testing and deployment technologies.

13. If there is a broken build in your Jenkins project, then what will you do?

First, we need to open the console output where the broken build is created and then see if there are any file changes that were missed. If we do not find any issues in this manner, then we can update our local workspace and replicate the problem and then try to solve it.

14. From one server to another, how do you copy or move your Jenkins jobs?

First, we need to copy our jobs directory from the old to the new server. There are multiple ways to do it. We can either move the job from the installation by simply copying the corresponding job directory or we can make a clone of the job directory by making an existing job’s copy. For this, we need to have a different name, which we can rename later.

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