Jenkins Cheat Sheet for Testers: Pipeline Syntax, Cron, Variables and CLI

This Jenkins cheat sheet collects the syntax testers use most: a complete Jenkinsfile for running an automation suite, the declarative pipeline blocks, cron schedules, parameters, built-in environment variables, post-build actions and the CLI. Bookmark it for when you're writing or debugging a pipeline.

A Complete Jenkinsfile for Test Automation

Put this file named Jenkinsfile in the root of your test project, then create a Pipeline job that reads it from Git ("Pipeline script from SCM"):

pipeline {
    agent any

    tools {
        maven 'Maven-3'          // names as configured in Manage Jenkins → Tools
        jdk 'JDK-21'
    }

    parameters {
        choice(name: 'BROWSER', choices: ['chrome', 'firefox', 'edge'], description: 'Browser to test')
        string(name: 'ENV', defaultValue: 'qa', description: 'Environment')
        booleanParam(name: 'SMOKE_ONLY', defaultValue: false, description: 'Run only the smoke suite')
    }

    environment {
        BASE_URL = "https://${params.ENV}.example.com"
    }

    triggers {
        cron('H 2 * * 1-5')      // nightly regression, Monday–Friday around 02:00
    }

    options {
        timeout(time: 60, unit: 'MINUTES')
        buildDiscarder(logRotator(numToKeepStr: '20'))
    }

    stages {
        stage('Checkout') {
            steps { checkout scm }
        }
        stage('Test') {
            steps {
                sh "mvn -B clean test -Dbrowser=${params.BROWSER} -DbaseUrl=${env.BASE_URL} -Dgroups=${params.SMOKE_ONLY ? 'smoke' : 'regression'}"
            }
        }
    }

    post {
        always {
            junit 'target/surefire-reports/*.xml'
            archiveArtifacts artifacts: 'target/screenshots/**', allowEmptyArchive: true
        }
        failure {
            echo "Build ${env.BUILD_NUMBER} failed: ${env.BUILD_URL}"
        }
    }
}

It runs a Maven/TestNG suite with a chosen browser and environment, runs nightly on weekdays, keeps the last 20 builds, publishes the TestNG/JUnit results and archives screenshots.

Declarative Pipeline Syntax

Run Browsers in Parallel

stage('Cross-browser') {
    parallel {
        stage('Chrome')  { steps { sh 'mvn -B test -Dbrowser=chrome' } }
        stage('Firefox') { steps { sh 'mvn -B test -Dbrowser=firefox' } }
    }
}

Cron Schedules in Jenkins

Five fields: minute hour day-of-month month day-of-week. H ("hash") lets Jenkins pick a fixed but spread-out value for each job, so not every job starts at exactly the same minute.

Built-in Environment Variables

Use them as ${env.BUILD_NUMBER} inside double-quoted strings. The full list for your server is at <jenkins-url>/env-vars.html.

Useful Steps for Testers

Jenkins CLI and Useful URLs

# download jenkins-cli.jar from <jenkins-url>/jnlpJars/jenkins-cli.jar
java -jar jenkins-cli.jar -s http://localhost:8080 -auth user:API_TOKEN list-jobs
java -jar jenkins-cli.jar -s http://localhost:8080 -auth user:API_TOKEN build Regression -p BROWSER=firefox -s -v
java -jar jenkins-cli.jar -s http://localhost:8080 -auth user:API_TOKEN safe-restart

Common Mistakes

1. Single quotes around variables: sh 'echo ${params.BROWSER}' passes the text literally to the shell. Use double quotes for Groovy variables: sh "echo ${params.BROWSER}".
2. Tests fail but the build is green: make sure Maven actually fails (don't add -Dmaven.test.failure.ignore=true unless you publish results with junit, which marks the build unstable).
3. Every job scheduled at 0 2 * * *: all jobs start at the same second. Use H 2 * * *.
4. Passwords in the Jenkinsfile: store them under Credentials and use withCredentials or credentials('id').
5. No timeout: a stuck browser can block an agent for hours. Always set options { timeout(...) }.

📚 Official documentation: Jenkins: Pipeline syntax · Jenkins CLI

Frequently Asked Questions

What does H mean in Jenkins cron?

H (hash) makes Jenkins choose a consistent value for each job within the range, spreading jobs out so they don't all start at once. H 2 * * * means "once around 2 AM".

Where do I put the Jenkinsfile?

In the root of your Git repository. Create a Pipeline job and choose "Pipeline script from SCM" so Jenkins reads it from the repository.

How do I pass parameters to a Jenkins pipeline?

Declare them in a parameters block and read them as params.NAME. Start the job with "Build with Parameters" or from the CLI with -p NAME=value.

How do I publish TestNG results in Jenkins?

TestNG writes JUnit-style XML to target/surefire-reports; publish it with junit 'target/surefire-reports/*.xml' in a post { always { } } block.

What is the difference between declarative and scripted pipeline?

Declarative uses the structured pipeline { } syntax shown here and is easier to read; scripted is plain Groovy inside node { }. Most teams use declarative.