DevOps Classroomnotes 15/May/2022

Working with Jenkins Pipelines

• In jenkins free style projects, when we install plugins we get UI, with Jenkins 2.0 with plugins we get some steps.
• Lets create a declarative pipeline for spring petclinic project

pipeline {
    agent { label 'JDK11' }
    options { 
        timeout(time: 1, unit: 'HOURS')
        retry(2) 
    }
    triggers {
        cron('0 * * * *')
    }
    stages {
        stage('Source Code') {
            steps {
                git url: 'https://github.com/GitPracticeRepo/spring-petclinic.git', 
                branch: 'main'
            }

        }
        stage('Build the Code') {
            steps {
                sh script: 'mvn clean package'
            }
        }
        stage('reporting') {
            steps {
                junit testResults: 'target/surefire-reports/*.xml'
            }

        }
    }
    post {
        success {
            // send the success email
            echo "Success"
        }
        unsuccessful {
            //send the unsuccess email
            echo "failure"
        }
    }
}

Email Notifications

• For email notifications i will be using fake SMTP Refer Here
• Configure Email Notifications in Jenkins
• Manage Jenkins => Configure System
  
• Lets configure a email notification
  
  
• To make the email or to know information about the job, Jenkins has environment al variables
  
  
  
• Find a way to include environment variable BUILD_ID and JOB_DISPLAY_URL in the email

mail bcc: '', body: 'Build Success', cc: '', 
    from: 'devops@qtdevops.com', replyTo: '', 
    subject: 'Build Succeded', to: 'qtdevops@gmail.com'

• Refer Here for the official docs
• Refer the jenkins file below

pipeline {
    agent { label 'JDK11' }
    options { 
        timeout(time: 1, unit: 'HOURS')
        retry(2) 
    }
    triggers {
        cron('0 * * * *')
    }
    stages {
        stage('Source Code') {
            steps {
                git url: 'https://github.com/GitPracticeRepo/spring-petclinic.git', 
                branch: 'main'
            }

        }
        stage('Build the Code') {
            steps {
                sh script: 'mvn clean package'
            }
        }
        stage('reporting') {
            steps {
                junit testResults: 'target/surefire-reports/*.xml'
            }

        }
    }
    post {
        success {
            // send the success email
            echo "Success"
            mail bcc: '', body: "BUILD URL: ${BUILD_URL} TEST RESULTS ${RUN_TESTS_DISPLAY_URL} ", cc: '', from: 'devops@qtdevops.com', replyTo: '', 
                subject: "${JOB_BASE_NAME}: Build ${BUILD_ID} Succeded", to: 'qtdevops@gmail.com'
        }
        unsuccessful {
            //send the unsuccess email
            mail bcc: '', body: "BUILD URL: ${BUILD_URL} TEST RESULTS ${RUN_TESTS_DISPLAY_URL} ", cc: '', from: 'devops@qtdevops.com', replyTo: '', 
                subject: "${JOB_BASE_NAME}: Build ${BUILD_ID} Failed", to: 'qtdevops@gmail.com'
        }
    }
}

* Environmental variables are built in into jenkins, if you need to create your own varaibles. Refer Here

* If you want to give an option to the user who is building the jobs, then we call these variables are parameters.
* Lets look at free style project







* Adding parameter to declartive pipeline

pipeline {
    agent { label 'JDK11' }
    options { 
        timeout(time: 1, unit: 'HOURS')
        retry(2) 
    }
    triggers {
        cron('0 * * * *')
    }
    parameters {
        choice(name: 'GOAL', choices: ['compile', 'package', 'clean package'])
    }
    stages {
        stage('Source Code') {
            steps {
                git url: 'https://github.com/GitPracticeRepo/spring-petclinic.git', 
                branch: 'main'
            }

        }
        stage('Build the Code') {
            steps {
                sh script: "mvn ${params.GOAL}"
            }
        }
        stage('reporting') {
            steps {
                junit testResults: 'target/surefire-reports/*.xml'
            }

        }
    }
    post {
        success {
            // send the success email
            echo "Success"
            mail bcc: '', body: "BUILD URL: ${BUILD_URL} TEST RESULTS ${RUN_TESTS_DISPLAY_URL} ", cc: '', from: 'devops@qtdevops.com', replyTo: '', 
                subject: "${JOB_BASE_NAME}: Build ${BUILD_ID} Succeded", to: 'qtdevops@gmail.com'
        }
        unsuccessful {
            //send the unsuccess email
            mail bcc: '', body: "BUILD URL: ${BUILD_URL} TEST RESULTS ${RUN_TESTS_DISPLAY_URL} ", cc: '', from: 'devops@qtdevops.com', replyTo: '', 
                subject: "${JOB_BASE_NAME}: Build ${BUILD_ID} Failed", to: 'qtdevops@gmail.com'
        }
    }
}

Upstream and downstream jobs

• Lets assume we configure the jenkins jobs in the following way
  
• How to acheive?
• Option 1: Post Build Actions
  
  
  
• Option 2: Build Triggers
  
• Now lets try to do this from pipeline
  • triggers: upstream
    

Better approach for running a pipeline

• Lets assume we build spring petclinic on node1 and deploy using node (ansible/terraform/cloudformation/arm/kubernetes)

pipeline {
    agent { label 'JDK11' }
    options { 
        timeout(time: 1, unit: 'HOURS')
        retry(2) 
    }
    triggers {
        cron('0 * * * *')
    }
    parameters {
        choice(name: 'GOAL', choices: ['compile', 'package', 'clean package'])
    }
    stages {
        stage('Source Code') {
            steps {
                git url: 'https://github.com/GitPracticeRepo/spring-petclinic.git', 
                branch: 'main'
            }

        }
        stage('Build the Code') {
            steps {
                sh script: "mvn ${params.GOAL}"
                stash name: 'spc-build-jar', includes: 'target/*.jar'
            }
        }
        stage('reporting') {
            steps {
                junit testResults: 'target/surefire-reports/*.xml'
            }
        }
        stage('deployment') {
            agent { label 'JDK8' }
            steps {
                unstash name: 'spc-build-jar'
                echo "clone the latest playbook"
                sh 'ansible --version'
            }
        }
    }
    post {
        success {
            // send the success email
            echo "Success"
            mail bcc: '', body: "BUILD URL: ${BUILD_URL} TEST RESULTS ${RUN_TESTS_DISPLAY_URL} ", cc: '', from: 'devops@qtdevops.com', replyTo: '', 
                subject: "${JOB_BASE_NAME}: Build ${BUILD_ID} Succeded", to: 'qtdevops@gmail.com'
        }
        unsuccessful {
            //send the unsuccess email
            mail bcc: '', body: "BUILD URL: ${BUILD_URL} TEST RESULTS ${RUN_TESTS_DISPLAY_URL} ", cc: '', from: 'devops@qtdevops.com', replyTo: '', 
                subject: "${JOB_BASE_NAME}: Build ${BUILD_ID} Failed", to: 'qtdevops@gmail.com'
        }
    }
}