Jenkins is an extremely important tool that you must upskill yourself in if you wish to become a DevOps Engineer. Many times recruiters have asked questions related to the Jenkins tool in DevOps interviews. We have collected the questions in this set of Jenkins interview questions after conducting extensive research. Below is a list of some of the most frequently asked Jenkins questions during job interviews:
Q1. What are the software prerequisites that must be met before Jenkins is installed?
Q2. How to configure and use third-party tools in Jenkins?
Q3. How to setup a Jenkins job?
Q4. How to take a backup of your Jenkins build jobs?
Q5. What are the steps included in a Jenkins pipeline?
Q6. What is the process for creating a backup and copy files in Jenkins?
Q7. Explain the Jenkins tool.
Q8. State some of the advantages of using Jenkins.
Q9. What are the requirements for using Jenkins?
Q10. What are some of the useful plugins in Jenkins?
This Jenkins Interview Questions and Answers blog can be classified into the three categories mentioned below:
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Basic Interview Questions
1. What are the software prerequisites that must be met before Jenkins is installed?
First, let us compare Jenkins with TeamCity:
||Not so widely used
The software prerequisites for installing Jenkins are that first we need to install Java Development Kit. We also need to install the Jakarta Enterprise Edition. Jenkins also comes with an embedded Jetty Runtime that can be used if WebSphere or Tomcat is not available.
2. How to configure and use third-party tools in Jenkins?
These are the steps used for working with a third-party tool in Jenkins:
- First, we have to install the third-party software.
- We need to have the plugin that supports the third-party tool.
- Then, we must configure the third-party tool in the admin console.
- We can then use the plug-in from the Jenkins build job.
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3. 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.
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4. How to take a backup of your Jenkins build jobs?
Within the XML configuration, each Jenkins build is stored. When this folder is copied, the configuration of all the build jobs that are managed by the Jenkins master is backed up. If we can perform a Jenkins Git integration, then it is good. When we copy the contents of the folder, we will see that the build jobs described in the folder will be restored when the Jenkins server is started the next time.
5. What are the steps included in a Jenkins pipeline?
A complete Jenkins pipeline includes building a project from the source code, putting it through a variety of units, integrating, testing for user acceptance and performance, and then finally deploying the packaged application on an application server.
So, the steps in a Jenkins pipeline can be listed as below:
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Intermediate Interview Questions
6. What is the process for creating a backup and copy files in Jenkins?
If we want to create a backup for our file, then we need to regularly backup our Jenkins_Home directory. This will include all the build jobs configuration, all the slave node configuration, and the build history. If we want to create a Jenkins backup, we can copy a job directory to a clone or can rename the directory. Learn how to get certified in DevOps by going through this DevOps Certification blog!
7. 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.
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8. State some of the advantages of using Jenkins.
Here are some of the most important advantages of Jenkins:
- We will get an automated build report every time a change is made to the source code.
- We will be able to achieve continuous integration with agile methodology principles.
- We can automate the maven release project with a few simple steps.
- Bugs can be easily tracked at an early development stage.
9. What are the requirements for using Jenkins?
Some of the requirements for using Jenkins are as follows:
- A source code repository like a Git repository
- A build script like a Maven script that is checked into the repository
10. What are some of the useful plugins in Jenkins?
Some of the important plugins that are used with Jenkins are:
- Git repository
- Amazon EC2
- HTML Publisher
- JDK Parameter Plugin
- Configuration Slicing Plugin
Advanced Interview Questions
11. Name two ways a Jenkins node agent can be configured to communicate back with the Jenkins master.
These are the mechanisms for starting a Jenkins node agent:
- From the browser window, launch a Jenkins node agent
- From the command line, launch a Jenkins node agent
When we launch a Jenkins node agent, it will download a JNLP file. A new process is launched on the client machine by the JNLP when it runs. Become a master of DevOps by going through this online DevOps Training in London!
12. How to turn off Jenkins Security if the administrative users have locked out of the admin console?
There is a folder that contains a file named config.xml. We need to change the settings to false for the security to be disabled when Jenkins is started the next time.
13. What is the process for securing Jenkins?
First, we need to ensure global security. Then, we have to make sure that Jenkins is integrated with the user directory through an appropriate plugin. The project matrix is enabled for fine tuning the access using the custom version-controlled script for automating the process of rights and privileges in Jenkins. The access to Jenkins data or folder is limited. We will run security audits on it.
14. How do you compare the tools, Hudson and Jenkins?
Initially, Jenkins was called Hudson. However, there were some issues, and due to this the name was changed from Hudson to Jenkins.
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15. 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.
16. 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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17. How to schedule builds in Jenkins?
Some steps for scheduling builds in Jenkins are as follows:
- First, we should have a source code management commit.
- We have to complete the other builds.
- Then, we have to schedule it to run at a specified time.
- We need to then give a manual build request.
18. Name some of the SCM tools that are supported by Jenkins.
Some of the important SCM tools that are supported by Jenkins include:
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