Jenkins

Jenkins - Overview

Jenkins is a software that allows continuous integration. Jenkins will be installed on a server where the central build will take place. The following flowchart demonstrates a very simple workflow of how Jenkins works.

Jenkins - Installation

Download Jenkins

You can download Jenkins following link Jenkins

Starting Jenkins

Open the command prompt. Browse to the directory where the jenkins.war file is present.

D:/> java -jar Jenkins.war

After the command is run, various tasks will run, one of which is the extraction of the war file which is done by an embedded webserver called winstone.

D:\>Java –jar Jenkins.war
Running from: D:\jenkins.war
Webroot: $user.home/ .jenkins
Sep 29, 2015 4:10:46 PM winstone.Logger logInternal
INFO: Beginning extraction from war file

Once the processing is complete without major errors, the following line will come in the output of the command prompt.

INFO: Jenkins is fully up and running

Accessing jenkins

Once jenkins is up and running, one can access jenkins from the link - http://localhost:8080

Create your firest Freestyle project

The build of a project is handled via jobs in Jenkins. Select New Item. Afterwards, enter a name for the job and select Freestype Job and press OK
Enter a description for the job and configure how many old jobs should be ratained.
Configure how the source code can be retrieved. If you for example using Git, enter the URL to the Git repository. If the repository is not public, you may also need to configure the credentials.

I typically delete the workspace before a build to avoid any side-effect. In the Build section you can add a build step, e.g., Windows batch command Press Save to finish the job definition. Press Build Now on the job page to validate the job works as expected.
After a while the job should go to green or blue (depending on your configuration), if successful. Click on the job and afterwards on Console Output to see the log file. Here you can analyze the build errors.

Creating your first Pepeline

What is a jenkins pipeline?

Jenkins Pipeline is a suite of plugin which support implementing and integrating continuous delivery pipeline into jenkins.
To get started quickly with Pipeline:

1. Copy one of the example below into your repository and name it Jenkinsfile.
2. Click the New item menu within Jenkins.
3. Provide a name for your new item(e.g My Pipeline) and select Multibranch Pipeline
4. Click the Add Source butto, choose the type of repository you want to use and fill in the details.
5. Click the Save button and watch your first Pipeline run!

Cleaning up and notifications

Since the post section of a Pipeline is guaranteed to run at the end of a Pipeline’s execution, we can add some notification or other steps to perform finalization, notification, or other end-of-Pipeline tasks.

Jenkinsfile(Declarative Pipeline)

pipeline {
    agent any
    stages {
        stage('No-op') {
            steps {
                bat 'ls'
            }
        }
    }
    post {
        always {
            echo 'One way or another, I have finished'
            deleteDir() /* clean up our workspace */
        }
        success {
            echo 'I succeeeded!'
        }
        unstable {
            echo 'I am unstable :/'
        }
        failure {
            echo 'I failed :('
        }
        changed {
            echo 'Things were different before...'
        }
    }
}

Example for Email:

post {
    failure {
        mail to: 'team@example.com',
             subject: "Failed Pipeline: ${currentBuild.fullDisplayName}",
             body: "Something is wrong with ${env.BUILD_URL}"
    }
}