Post, Triggers & Tools

Actions after pipeline finishes, automatic triggers, and tool configuration.

---

Post Block

The post block runs after stages finish. Use it for cleanup, notifications, and reports.

pipeline {
    agent any

    stages {
        stage('Test') {
            steps { sh 'pytest tests/' }
        }
    }

    post {
        always {
            junit '**/report.xml'
            echo 'Pipeline finished'
        }
        success {
            echo 'All tests passed!'
        }
        failure {
            echo 'Something went wrong'
        }
        cleanup {
            cleanWs()
        }
    }
}

Post Conditions

Condition	Runs When
always	Every time, no matter what
success	Pipeline succeeded
failure	Pipeline failed
unstable	Pipeline marked unstable (e.g. test failures)
changed	Status changed from previous build
fixed	Previous build failed, this one succeeded
regression	Previous build succeeded, this one failed
aborted	Pipeline was cancelled
cleanup	After all other post conditions (always runs)

Stage-Level Post

You can also use post inside a stage:

stage('Test') {
    steps {
        sh 'pytest --junitxml=report.xml tests/'
    }
    post {
        always {
            junit 'report.xml'
        }
        failure {
            sh 'cat pytest-debug.log || true'
        }
    }
}

---

Triggers

Automatic ways to start a pipeline.

pipeline {
    agent any

    triggers {
        // Poll SCM every 5 minutes
        pollSCM('H/5 * * * *')

        // Run on schedule (nightly at 2 AM)
        cron('H 2 * * *')

        // Trigger when another job finishes
        upstream(
            upstreamProjects: 'build-library',
            threshold: hudson.model.Result.SUCCESS
        )
    }

    stages { /* ... */ }
}

Trigger Types

Trigger	Purpose	Example
pollSCM	Check Git for changes	pollSCM('H/5 * * * *')
cron	Scheduled builds	cron('H 2 * * *')
upstream	After another job	upstream('job-name')

Use webhooks instead of pollSCM

Configure GitHub/GitLab webhooks to trigger builds instantly. pollSCM adds delay and creates extra load on Jenkins.

Cron Syntax

MINUTE  HOUR  DAY_OF_MONTH  MONTH  DAY_OF_WEEK

H/15    *     *             *      *       → every 15 minutes
H       2     *             *      *       → daily at 2 AM
H       2     *             *      1-5     → weekdays at 2 AM

H (hash) spreads load — Jenkins picks a stable random minute for each job.

---

Tools

The tools block installs tools automatically (must be configured in Jenkins Global Tool Configuration):

pipeline {
    agent any

    tools {
        jdk 'jdk-17'
        nodejs 'node-20'
        maven 'maven-3.9'
    }

    stages {
        stage('Build') {
            steps {
                sh 'java -version'
                sh 'node --version'
                sh 'mvn --version'
            }
        }
    }
}

Prefer Docker over tools

Instead of installing tools on Jenkins agents, use Docker images with tools pre-installed. It is more portable and reproducible.

---

Notifications

Slack

post {
    success {
        slackSend(
            channel: '#ci',
            color: 'good',
            message: "Build passed: ${env.JOB_NAME} #${env.BUILD_NUMBER}"
        )
    }
    failure {
        slackSend(
            channel: '#ci',
            color: 'danger',
            message: "Build failed: ${env.JOB_NAME} #${env.BUILD_NUMBER}"
        )
    }
}

Email

post {
    failure {
        emailext(
            subject: "FAILED: ${env.JOB_NAME} #${env.BUILD_NUMBER}",
            body: "Check: ${env.BUILD_URL}",
            to: 'team@example.com'
        )
    }
}