Jenkinsfile Generator

Jenkinsfile Generator Skill

Generate production-ready Jenkinsfiles following best practices. All generated files are validated using devops-skills:jenkinsfile-validator skill.

Trigger Phrases

• "Generate a CI pipeline for Maven/Gradle/npm"
• "Create a Jenkins deployment pipeline with approvals"
• "Build a Jenkinsfile with parallel test stages"
• "Create a scripted pipeline with dynamic stage logic"
• "Scaffold a Jenkins shared library"
• "Generate a Jenkinsfile for Docker or Kubernetes agents"

When to Use

• Creating new Jenkinsfiles (declarative or scripted)
• CI/CD pipelines, Docker/Kubernetes deployments
• Parallel execution, matrix builds, parameterized pipelines
• DevSecOps pipelines with security scanning
• Shared library scaffolding

Declarative vs Scripted Decision Tree

1. Choose Declarative by default when stage order and behavior are mostly static.
2. Choose Scripted when runtime-generated stages, complex loops, or dynamic control flow are required.
3. Choose Shared Library scaffolding when request is about reusable pipeline functions (vars/, src/, resources/).
4. If unsure, start Declarative and only switch to Scripted if requirements cannot be expressed cleanly.

Template Map

Quick Reference

// Minimal Declarative Pipeline
pipeline {
    agent any
    stages {
        stage('Build') { steps { sh 'make' } }
        stage('Test') { steps { sh 'make test' } }
    }
}

// Error-tolerant stage
stage('Flaky Tests') {
    steps {
        catchError(buildResult: 'SUCCESS', stageResult: 'UNSTABLE') {
            sh 'run-flaky-tests.sh'
        }
    }
}

// Conditional deployment with approval
stage('Deploy') {
    when { branch 'main'; beforeAgent true }
    input { message 'Deploy to production?' }
    steps { sh './deploy.sh' }
}

Core Capabilities

1. Declarative Pipelines (RECOMMENDED)

Process:

1. Read templates for structure reference:
   • Read assets/templates/declarative/basic.Jenkinsfile to understand the standard structure
   • Templates show the expected sections: pipeline → agent → environment → options → parameters → stages → post
   • For complex requests, adapt the structure rather than copying verbatim
2. Consult reference documentation:
   • Read references/best_practices.md for performance, security, and reliability patterns
   • Read references/common_plugins.md for plugin-specific syntax
3. Generate with required elements:
   • Proper stages with descriptive names
   • Environment block with credentials binding (never hardcode secrets)
   • Options: timeout, buildDiscarder, timestamps, disableConcurrentBuilds
   • Post conditions: always (cleanup), success (artifacts), failure (notifications)
   • Always add failFast true or parallelsAlwaysFailFast() for parallel blocks
   • Always include fingerprint: true when using archiveArtifacts
4. ALWAYS validate using devops-skills:jenkinsfile-validator skill

2. Scripted Pipelines

When: Complex conditional logic, dynamic generation, full Groovy control Process:

1. Read templates for structure reference:
   • Read assets/templates/scripted/basic.Jenkinsfile for node/stage patterns
   • Understand try-catch-finally structure for error handling
2. Implement try-catch-finally for error handling
3. ALWAYS validate using devops-skills:jenkinsfile-validator skill

3. Parallel/Matrix Pipelines

Use parallel {} block or matrix {} with axes {} for multi-dimensional builds.

• Default behavior is fail-fast for generated parallel pipelines (parallelsAlwaysFailFast() or stage-level failFast true).

4. Security Scanning (DevSecOps)

Add SonarQube, OWASP Dependency-Check, Trivy stages with fail thresholds.

5. Shared Library Scaffolding

python3 scripts/generate_shared_library.py --name my-library --package org.example

Declarative Syntax Reference

Agent Types

agent any                                    // Any available agent
agent { label 'linux && docker' }           // Label-based
agent { docker { image 'maven:3.9.11-eclipse-temurin-21' } }
agent { kubernetes { yaml '...' } }         // K8s pod template
agent { kubernetes { yamlFile 'pod.yaml' } } // External YAML

Environment & Credentials

environment {
    VERSION = '1.0.0'
    AWS_KEY = credentials('aws-key-id')     // Creates _USR and _PSW vars
}

Options

options {
    buildDiscarder(logRotator(numToKeepStr: '10'))
    timeout(time: 1, unit: 'HOURS')
    disableConcurrentBuilds()
    timestamps()
    parallelsAlwaysFailFast()
    durabilityHint('PERFORMANCE_OPTIMIZED')  // 2-6x faster for simple pipelines
}

Parameters

parameters {
    string(name: 'VERSION', defaultValue: '1.0.0')
    choice(name: 'ENV', choices: ['dev', 'staging', 'prod'])
    booleanParam(name: 'SKIP_TESTS', defaultValue: false)
}

When Conditions

Add beforeAgent true to skip agent allocation if condition fails.

Error Handling

catchError(buildResult: 'UNSTABLE', stageResult: 'FAILURE') { sh '...' }
warnError('msg') { sh '...' }      // Mark UNSTABLE but continue
unstable(message: 'Coverage low')   // Explicit UNSTABLE
error('Config missing')             // Fail without stack trace

Post Section

post {
    always { junit '**/target/*.xml'; cleanWs() }
    success { archiveArtifacts artifacts: '**/*.jar', fingerprint: true }
    failure { slackSend color: 'danger', message: 'Build failed' }
    fixed { echo 'Build fixed!' }
}

Order: always → changed → fixed → regression → failure → success → unstable → cleanup

NOTE: Always use fingerprint: true with archiveArtifacts for build traceability and artifact tracking.

Parallel & Matrix

IMPORTANT: Always ensure parallel blocks fail fast on first failure using one of these approaches:

Option 1: Global (RECOMMENDED) - Use parallelsAlwaysFailFast() in pipeline options:

options {
    parallelsAlwaysFailFast()  // Applies to ALL parallel blocks in pipeline
}

This is the preferred approach as it covers all parallel blocks automatically.

Option 2: Per-block - Use failFast true on individual parallel stages:

stage('Tests') {
    failFast true  // Only affects this parallel block
    parallel {
        stage('Unit') { steps { sh 'npm test:unit' } }
        stage('E2E') { steps { sh 'npm test:e2e' } }
    }
}

NOTE: When parallelsAlwaysFailFast() is set in options, explicit failFast true on individual parallel blocks is redundant.

stage('Matrix') {
    failFast true
    matrix {
        axes {
            axis { name 'PLATFORM'; values 'linux', 'windows' }
            axis { name 'BROWSER'; values 'chrome', 'firefox' }
        }
        excludes { exclude { axis { name 'PLATFORM'; values 'linux' }; axis { name 'BROWSER'; values 'safari' } } }
        stages { stage('Test') { steps { echo "Testing ${PLATFORM}/${BROWSER}" } } }
    }
}

Input (Manual Approval)

stage('Deploy') {
    input { message 'Deploy?'; ok 'Deploy'; submitter 'admin,ops' }
    steps { sh './deploy.sh' }
}

IMPORTANT: Place input outside steps to avoid holding agents.

Scripted Syntax Reference

node('agent-label') {
    try {
        stage('Build') { sh 'make build' }
        stage('Test') { sh 'make test' }
    } catch (Exception e) {
        currentBuild.result = 'FAILURE'
        throw e
    } finally {
        deleteDir()
    }
}

// Parallel
parallel(
    'Unit': { node { sh 'npm test:unit' } },
    'E2E': { node { sh 'npm test:e2e' } }
)

// Environment
withEnv(['VERSION=1.0.0']) { sh 'echo $VERSION' }
withCredentials([string(credentialsId: 'key', variable: 'KEY')]) { sh 'curl -H "Auth: $KEY" ...' }

@NonCPS for Non-Serializable Operations

@NonCPS
def parseJson(String json) {
    new groovy.json.JsonSlurper().parseText(json)
}

Rules: No pipeline steps (sh, echo) inside @NonCPS. Use for JsonSlurper, iterators, regex Matchers.

Docker & Kubernetes

Docker Agent

agent { docker { image 'maven:3.9.11'; args '-v $HOME/.m2:/root/.m2'; reuseNode true } }

Build & Push

def img = docker.build("myapp:${BUILD_NUMBER}")
docker.withRegistry('https://registry.example.com', 'creds') { img.push(); img.push('latest') }

Kubernetes Pod

agent {
    kubernetes {
        yaml '''
apiVersion: v1
kind: Pod
spec:
  containers:
  - name: maven
    image: maven:3.9.11-eclipse-temurin-21
    command: [sleep, 99d]
'''
    }
}
// Use: container('maven') { sh 'mvn package' }

Shared Libraries

@Library('my-shared-library') _
// or dynamically: library 'my-library@1.0.0'

// vars/log.groovy
def info(msg) { echo "INFO: ${msg}" }

// Usage
log.info 'Starting build'

Validation Workflow

CRITICAL: ALWAYS validate using devops-skills:jenkinsfile-validator skill:

1. Generate Jenkinsfile
2. Invoke devops-skills:jenkinsfile-validator skill
3. Handle validation results by severity:
   • ERRORS: MUST fix before presenting to user - these break the pipeline
   • WARNINGS: SHOULD fix - these indicate potential issues
   • INFO/SUGGESTIONS: Consider applying based on use case:
     • failFast true for parallel blocks → apply by default
     • Build triggers → ask user if they want automated builds
     • Other optimizations → apply if they improve the pipeline
4. Re-validate after fixes
5. Only present validated Jenkinsfiles to user

Validation commands:

# Full validation (syntax + security + best practices)
bash ../jenkinsfile-validator/scripts/validate_jenkinsfile.sh Jenkinsfile

# Syntax only (fastest)
bash ../jenkinsfile-validator/scripts/validate_jenkinsfile.sh --syntax-only Jenkinsfile

Generator Scripts

When to use scripts vs manual generation:

• Use scripts for: Simple, standard pipelines with common patterns (basic CI, straightforward CD)
• Use manual generation for: Complex pipelines with multiple features (parallel tests + security scanning + Docker + K8s deployments), custom logic, or non-standard requirements

Script Arguments: Required vs Optional

• generate_declarative.py
• Required: --output
• Optional: --stages, --agent, --build-tool, --build-cmd, --test-cmd, --deploy-*, --notification-*, --archive-artifacts, --k8s-yaml
• Notes:
• --k8s-yaml accepts either inline YAML content or a path to an existing .yaml/.yml file.
• Stage keys are validated ([a-z0-9_-]) and shell commands are emitted as escaped Groovy literals.
• generate_scripted.py
• Required: --output
• Optional: stage/agent/SCM/notification parameters depending on requested pipeline features.
• generate_shared_library.py
• Required: --name
• Optional: --package, --output
• Shared library deployment helper now includes explicit rollout target (deployment/<name>) and notification helper emits valid HTML email bodies.

# Declarative (simple pipelines)
python3 scripts/generate_declarative.py --output Jenkinsfile --stages build,test,deploy --agent docker

# Scripted (simple pipelines)
python3 scripts/generate_scripted.py --output Jenkinsfile --stages build,test --agent label:linux

# Shared Library (always use script for scaffolding)
python3 scripts/generate_shared_library.py --name my-library --package com.example

Done Criteria

• Pipeline style selection (Declarative vs Scripted) is explicit and justified.
• Generated Jenkinsfiles pass smoke validation with executable validator commands.
• Parallel pipelines are fail-fast by default unless user explicitly requests otherwise.
• Custom stage names and shell commands are safely emitted (no unescaped Groovy literals).
• --k8s-yaml works with both inline YAML and existing file paths.
• Notification-enabled post blocks still archive artifacts when requested.

Plugin Documentation Lookup

Always consult Context7 or WebSearch for:

• Plugins NOT covered in references/common_plugins.md
• Version-specific documentation requests
• Complex plugin configurations or advanced options
• When user explicitly asks for latest documentation

May skip external lookup when:

• Using basic plugin syntax already documented in references/common_plugins.md
• Simple, well-documented plugin steps (e.g., basic sh, checkout scm, junit)

Plugins covered in common_plugins.md: Git, Docker, Kubernetes, Credentials, JUnit, Slack, SonarQube, OWASP Dependency-Check, Email, AWS, Azure, HTTP Request, Microsoft Teams, Nexus, Artifactory, GitHub

Lookup methods (in order of preference):

1. Context7: mcp__context7__resolve-library-id with /jenkinsci/<plugin-name>-plugin
2. WebSearch: Jenkins [plugin-name] plugin documentation 2025
3. Official: plugins.jenkins.io, jenkins.io/doc/pipeline/steps/

References

• references/best_practices.md - Performance, security, reliability patterns
• references/common_plugins.md - Git, Docker, K8s, credentials, notifications
• assets/templates/ - Declarative and scripted templates
• devops-skills:jenkinsfile-validator skill - Syntax and best practices validation

Always prefer Declarative unless scripted flexibility is required.