Jenkins Interview Questions- Part 4

Answer:

• Agent: It is a directive to guide Jenkins on executing the Pipeline in a particular order & manner.
• Post-section: If you add some notification to perform other tasks at the end of the Pipeline, the post-section will run at the end of each Pipeline’s execution.
• Jenkinsfile: It is a text file wherein all the definitions of Pipelines are defined. It is checked in the source control repository.

Answer:

We need the following to use Jenkins:

1. An accessible source code repository like a Git repository
2. A working build script, such as a Maven Script, checked into the repository

Answer:

The following are the types of jobs in Jenkins:

• Pipeline
• External Job
• Maven project
• Freestyle project
• Multibranch Pipeline
• Multi-configuration project
• GitHub organization

Answer:

A Scripted Pipeline is built on the top of an underlying Pipeline sub-system. Unlike Declarative, Scripted Pipeline is an efficient general-purpose DSL built with Groovy. Most functionality provided by the Groovy language is made accessible to Scripted Pipeline users, meaning it is a flexible tool with which one can author continuous delivery pipelines.

Answer:

Environment Directive represents a sequence of key-value pairs defined as Environment Variables for all steps, based on where the Environment Directive is located in the Pipeline. It supports a special helper method credentials() used to access predefined credentials by their identifier in the Jenkins environment.

Answer:

Below are the ways of scheduling build in Jenkins:

• By source code management commits.
• After the completion of other builds.
• Build could be scheduled to run at a particular time using the CRON jobs.
• The build could be scheduled through Manual Build Requests.

Answer:

The role-based strategy plugin provides three main functionalities:

• Global roles: Across a project with permission job, run & Source Control Management (SCM)
• Project role: It can access a particular project job or run a category
• Slave roles: It only sets the node-related permissions.

Answer:

A stage block denotes conceptually distinct subparts of tasks performed in the entire Pipeline. Stages have a sequence of multiple-stage directives; the stages section contains a bulk of “work” described by the Pipeline. It is recommended that stages have at least one stage directive for each distinctive part of the continuous delivery process, like Test, Build, & Deploy.

Answer:

Flow control in Jenkins supports the scripted pipeline or pipeline structure for executing the top to bottom of a Jenkins file.

Answer:

The declarative pipeline is a relatively new Jenkins feature that supports a pipeline as a code concept. It simplifies pipeline code & makes it easier to read & write. The pipeline code is written in the Jenkinsfile, which can be checked into the source control management system like Git. The structure & syntax of a declarative pipeline is as follows:

• any- It denotes the entire pipeline will run on any available agent.
• docker- It helps to run a pipeline in a Docker environment.
• none- It represents that all the stages under a block will have to be declared with an agent separately.
• label- It is only a label for the Jenkins environment.

Answer:

An SCM or Source Code Management specifies the location of a source code in Jenkins. The entry point to an SCM is defined as jenkins_jobs.scm. A job defined with the SCM attribute accepts numerous SCM definitions. Some of the popular SCM tools are Git, CVS, Clearcase, Perforce, AccuRev, Subversion, Mercurial, & RTC.

Answer:

1. Jenkins, by default, runs on a port number 8080; if you want to change the existing port from 8080 to any other desired port number, take the following steps:
   • Run Jenkins with the command line;
   • Then, execute the command, java -jar -httpPort=desired_port jenkins.war.
2. If Jenkins is installed with the Windows package, then:
   • Go to the Jenkins directory or Program Files;
   • And, open Jenkins.xml in the editor
   • Find –httpPort=8080 & replace the port number 8080 with a new port number.

Answer:

To configure Docker in Jenkins, follow these steps:

• First, click on the “Manage Jenkins” on the Jenkins dashboard;
• Select the “Manage Plugins” on the Configuration page;
• Now, click on Available in the tabbed interface & it will list all the available Jenkins plugins for installation;
• Search for the Docker plugin in the search box; you get to choose from multiple Docker plugins;
• Finally, select the Docker plugin.

Answer:

You can use the GitHub plugin whenever you want to integrate Jenkins with GitHub projects. It enables scheduling a build, pulling code files & data from the GitHub repos to a Jenkins machine, and automatically triggers each build on the Jenkins server after each commit on the Git repository. It saves time & allows you to incorporate a specific project into the CI process.

Answer:

Follow these steps to configure Jenkins with Maven:

1. Go to the Jenkins dashboard & navigate to Manage Jenkins, select Configure System;
2. Now scroll down till you see the Maven section & go to Add Maven;
3. Uncheck the ‘Install automatically’ box;
4. Add & save a name for the setting & location of the MAVEN_HOME;
5. Now, you can create a job with a ‘Maven project’ option.

Answer:

You can create the slave node in Jenkins by these simple steps:

1. Click on the Manage Jenkins option
2. Select the option Manage Nodes
3. Enter a name for the slave node & click OK
4. Save the changes