DevOps Classroom Series – 29/Dec/2019

Scripted Pipeline

• Directly allows users to write Groovy
• Learning curve towards Groovy
• Main blocks/steps are
  • Node
  • Stage
  • git
  • sh
  • bat
• Example

node('mvn') {
    stage('scm') {
        git 'https://github.com/springpetclinic.git'
    }
    stage('build') {
        if env.branch == 'master'
            sh 'mvn package'
        else
            sh 'mvn clean package'
    }
}

Declarative Pipeline

• Created Declarative Syntax for Jenkins (DSL)
• Simpler learning Curve
• Declarative Steps are
  • pipeline
  • stages
  • stage
  • label
  • when
  • agent
  • sh
  • git
• Example

pipeline {
    agent {
        label 'MVN'
    }
    stages {
        stage ('git') {
            ....
        }
        stage ('build') {
            ......
            when branch == 'master'
               ....
        }
    }
}

• Refer Here for specifics

Configuring Tools to Jenkins

• Configure Tools like
  • git
  • Maven
  • Docker
  • Ant
  • Gradle
  • Artifactory
  • SonarQube

Multi Branch Pipeline

• Ensure every branch has a Jenkinsfile and Jenkins automatically indexes all the branches of your project.
• Multi branches builds can be triggered at one shot.
• Navigate to New-Item => Multi Branch Pipeline
• Best practice is to implement git hooks to scan multi branch pipeline.

Writing Jenkins Declarative Pipelines

• Refer Here for official docs
• Basic Pipeline Sytnax

pipeline {
    // pipeline stuff
}

• Agent: Where the job has to run

// run anywhere
agent any 

// run on the agents with label MAVEN
agent {
    label 'MAVEN'
}

• Stages: configure sequence of stages. Example – do git clone and then mvn package

pipeline {
    agent any
    stages {
        stage('git') {
            git 'https://github.com/asquarezone/game-of-life.git'
        }
        stage('mvn') {
            sh 'mvn clean package'
        }
    }
}

• Parallel execution of stages

parallel {
    stage('act1') {
        steps {
            echo 'act1'
        }
    }
    stage('act2') {
        steps {
            echo 'act2'
        }
        
    }
}

• when: Conditional check to execute stage or not
• env: To access jenkins environmental variables use env.<variable name> in scripted pipeline
• parameters: To set parameters in declarative pipelines. Refer Here

pipeline {
    agent any
    parameters {
        string(name: 'learning' )
    }
    stages {
        stage('test') {
            steps {
                echo '${params.learning} is the parameter'
            }
        }
    }
}

• Build Triggers: Refer Here
• Input: Refer Here
• Also refer Globals Section from Pipeline Syntax Page
• Also refer Steps

pipeline {
    agent any
    parameters {
        string(name: 'purpose',default: 'learning')
    }
    stages {
        stage('git'){
            git url: 'https://github.com/spc.git', branch: 'sprint-2'
        }
        stage('build the code'){
            sh script: 'mvn package', label: 'build'
        }
        stage('archive the artifacts'){
            archiveArtifacts archive: 'target/*.jar', onlyIfSuccessful: true
        }
    }
}