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Jenkins Interview Questions

Prepare better with the best interview questions and answers, and walk away with top interview tips. These interview questions and answers will boost your core interview skills and help you perform better. Be smarter with every interview.

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Beginner

The user needs to open the console output for the build and will try to see if any file changes that were missed during building the project. If there are no issues on that then a better approach would be clean and update his local workspace to replicate the problem on their local machine and will try to solve it.

To make sure Jenkins build is not broken at all we need to make sure that we perform a successful clean install on the local machine with all unit tests. Then make sure that all code changes are checked in without any issues. Then synchronize with a repository to make sure that all required config and changes and any differences are checked into the repository. 

The below are the ways of scheduling build in Jenkins

  • Builds can be triggered by source code management commits.
  • Builds can be triggered sequentially after completion of other builds.
  • Can be scheduled to run at a specified time using the CRON jobs
  • Manual Build Requests.

Please follow the below steps,

  • Slide a job from one installation of Jenkins to another by copying the related job directory
  • Make a copy of an already existing job by making a clone of a job directory by a different name
  • Renaming an existing job by renaming a directory.

The tool which is generally used is Ansible and it has mainly featured for the cloud deployment of the automated software development approach. This tool has many additional features with it and the best thing is it can easily be deployed as an orchestration tool. 

The role-based strategy plugin allows us to create three different types of roles as describes below,

  •  Global Roles: Some of the roles such as admin, job creator, anonymous can be created while selecting this option. The user can allow setting Overall, slave, job, and View and SCM permissions on a global basis.
  •  Project roles: This job is basically to allow the creation of Job and Run permissions on a project basis.
  •  Slave roles: This job is only to set node-related permissions.

Jenkins is basically one of the most popular tools for automating the whole process of Software development. One of the best things about using Jenkins is that it has an inbuilt plug-in for continuous integration. Also talks very well with the version control system, to simply let the users make sure of monitoring the build systems. It is possible for the users to catch the build failure through Jenkins. Also, with this technology, it is possible to get notifications upon any single change made in the repository. Developers can simply get an idea regarding the build report success or the failure and this can be done by the Jenkins integration with LDAP. In addition to this, the continuous integration of agile development can also be assured simply. The best thing is Jenkins can simply let the users look for the errors and major bugs in the early phase of development which later create a lot of issues.

Creating a chain of jobs in Jenkins is the process of automatically starting the sequential job after one job is executed successfully. This approach lets the user build multi-step build pipelines or trigger the rebuild of a project if one of the Project dependencies is updated.

A Jenkins file is a text file that contains the definition of a Jenkins Pipeline and it is generally checked into source control. 

  • Audit trail for the Pipeline can be monitored
  • It serves as a single source of truth for the Pipeline, which can be viewed and edited by multiple members of the project.

The post section of a Pipeline in Jenkins will definitely run at the end of a Pipeline’s execution. The user can use this in order to add some kind of notification or other steps to perform finalization or other end-of-Pipeline tasks.

Jenkins supports a wide range of Source Code Management tools and few of them are mentioned below,

  • AccuRev
  • CVS
  • Subversion
  • Git
  • Mercurial
  • Perforce
  • Clearcase
  • RTC

The environment directive specifies a sequence of key-value pairs which will be defined as environment variables for the all steps, or stage-specific steps, depending on where the environment directive is located within the Pipeline. This directive supports a special helper method credentials() which can be used to access pre-defined Credentials by their identifier in the Jenkins environment.

A stage block defines a conceptually distinct subset of tasks performed through the entire Pipeline. Stages contain a sequence of one or more stage directives, the stages section is where the bulk of the "work" described by a Pipeline will be located. Minimum, it is recommended that stages contain at least one stage directive for each discrete part of the continuous delivery process, such as Build, Test, and Deploy.

Jenkins is an open source automation server written in Java. As an extensible automation server, Jenkins can be used as a simple CI server or turned into the continuous delivery hub for any project.

Impress Employers with your Jenkins knowledge

So, this is all about the best interview questions and answers on Jenkins. I hope these Jenkins interview questions help you crack your interview.

Prepare yourself with the best interview questions and answers on Jenkins to land your dream job!

Advanced

Below are the steps to deploy a custom build of a core plugin:

  •  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. 

One of the best advantages of using Jenkins is its feature of simply storing all the data including the Build artifacts and all the associated logs in it. In order to back up the setup and all other information that is required, the users have to make sure that they have enabled the cloning of job directory or replicate the same post from which backup can be created with all the default options. Also, simply JENKINS_HOME directory can be copied to a different backup folder.

The below steps needs to be followed for starting & stopping of Jenkins manually

  • Open the command line prompt and navigate until you get to the Jenkins installation directory.
  • Then use one of the following commands,
    • Starting the Jenkins – “Jenkins.exe start” 
    • Restarting the Jenkins – “Jenkins.exe restart”
    • Stopping the Jenkins – “Jenkins.exe stop”

The Jenkins Job DSL Plugin is basically the Domain Specific Language (DSL) plugin that allows users to describe jobs using a scripting language named Groovy, the plugin can manage the scripts and updating of the Jenkins jobs which are created and maintain them as a result.

CI (Continuous integration)

Continuous Integration is a process that helps developers to integrate code into a shared repository several times. Each check-in is verified by an automated build process, allowing teams to detect problems early. 

CD (Continuous delivery)

Continuous delivery is an extension of a continuous integration process which helps to make sure that new changes can be released to the customers quickly in a sustainable way.

A build trigger may be used for various purposes depending on the context of the project.

For a specific instance if the user would like to have a CI/CD pipeline setup using plain Jenkins. They will have the build triggers to trigger downstream projects such as

  • Integration tests
  • Code Scans
  • Performance Tests
  • End to End Tests
  • Deployment.

The above stages will be chained to the parent job and can be triggered one by one or in parallel depending on the stage. Build periodically can be used to run on standard jobs. Then we can set up the test jobs to build periodically late evenings at a fixed time. Polling the latest code using SCM and checking if there is new code committed in your repository and build based on that.

With the help of input directives, the user could prompt the inputs with the help of input steps. The stage is paused after different options have been applied and before we can enter to the stage agent to evaluate its condition. Once the input is approved, we could continue with the stage ahead. The parameters that are given as the part of input submission will be available in the environment for the rest of the stage.

The scripted pipeline is very much similar to the declarative pipeline that's built on the top of the underlying pipeline sub-system. The scripted pipeline is based on a general-purpose language based on Groovy. A list of features or benefits that are available in Groovy can be used along scripted pipeline too. In brief, this is a highly flexible tool that can be used in multiple continuous delivery pipelines.

Blue Ocean is a project that rethinks the user experience of Jenkins, modeling and presenting the process of software delivery by surfacing information that’s important to development teams with as few clicks as possible, while still staying true to the extensibility that is core to Jenkins. While this project is in the alpha stage of development, the intent is that Jenkins users can install Blue Ocean side-by-side with the Jenkins Classic UI via a plugin.

Description

Jenkins, a very important tool in DevOps that automates the rest of the process with the help of plugins once the changes are made in a source code repository (SCR). If you are applying for any DevOps role or any Cloud-native practitioner role, you can encounter many Jenkins interview questions. 
Following are the most frequently asked interview questions and answers on Jenkins. These interview questions on Jenkins can be useful for freshers and experienced to clear the interview. 
When any organization seeking to fill the vacancies for the DevOps roles, they mostly look for the following set of skills in an individual and these are:
An individual should be fluent in web languages like Ruby, Python, PHP or Java.
An individual should be aware of the various infrastructure automation tools like Chef, Puppet, Ansible, SaltStack or Windows PowerShell DSC.
Interpersonal skills that help you communicate and collaborate across teams and roles.
This skills-set will make you eligible for the interview. Jenkins basic interview questions and answers mentioned here will help you to prepare for the interview. Here is a list of the top Jenkins interview questions and answers.  
 

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