What is Jenkins?
Jenkins is an open-source automation server written in Java that enables developers to reliably build, test, and deploy their software. It facilitates Continuous Integration (CI) and Continuous Deployment (CD) by automating the software development lifecycle. Jenkins supports building, deploying, and automating any project through its extensive plugin ecosystem.
Originally developed as "Hudson" in 2004 by Kohsuke Kawaguchi at Sun Microsystems, Jenkins has grown to become one of the most popular DevOps tools. With over 1,800 plugins and a large community, Jenkins can integrate with virtually any tool in the software development and deployment toolchain.
Jenkins Capacity Calculator
Memory Needed: 5GB
Disk Space: 65GB
Performance Score: 100/100
Jenkins Core Concepts
Jobs/Projects
Basic units of work in Jenkins that define what actions to perform.
• Pipeline projects
• Multi-configuration
• External job monitoring
• Organizational folders
Builds
Execution instances of jobs with their own workspace and results.
• Console output
• Test results
• Artifacts
• Build parameters
Plugins
Extensions that add functionality to Jenkins core platform.
• SCM integrations
• Build tools
• Deployment tools
• Notification systems
Nodes
Machines where Jenkins can execute builds (master and agents).
• Agent nodes (workers)
• Executors per node
• Node labels
• Cloud nodes
Jenkins Pipeline Types
Declarative Pipeline
Structured, opinionated syntax that provides a simplified way to define pipelines.
pipeline {
agent any
stages {
stage('Build') {
steps {
sh 'make build'
}
}
stage('Test') {
steps {
sh 'make test'
}
}
}
}
Scripted Pipeline
Groovy-based DSL that provides maximum flexibility for complex scenarios.
node {
stage('Checkout') {
checkout scm
}
stage('Build') {
sh 'make build'
}
stage('Test') {
parallel(
unit: { sh 'make unit-test' },
integration: { sh 'make integration-test' }
)
}
}
Jenkins Build Triggers
SCM Triggers
Automatic builds triggered by source code changes.
• SCM polling
• GitHub/GitLab integration
• Branch-based triggers
• Pull request builds
Time-based Triggers
Scheduled builds using cron-like syntax.
• Nightly builds
• Weekly reports
• Maintenance windows
• Load testing schedules
Dependency Triggers
Builds triggered by completion of upstream projects.
• Pipeline stages
• Multi-project dependencies
• Conditional triggers
• Parameterized triggers
Manual Triggers
User-initiated builds with optional parameters.
• Remote triggers
• API-triggered builds
• Approval workflows
• Emergency deployments
Real-World Jenkins Implementations
Netflix
Uses Jenkins for massive-scale deployment pipeline across thousands of microservices.
- • 2,500+ Jenkins instances
- • 150,000+ builds per day
- • Spinnaker integration
- • Canary deployments
Samsung
Leverages Jenkins for mobile app CI/CD and firmware development.
- • Android build automation
- • Device testing farms
- • Code quality gates
- • Release management
Powers continuous deployment for LinkedIn's platform and services.
- • Multi-datacenter deployments
- • A/B testing integration
- • Performance testing
- • Rollback automation
NASA JPL
Uses Jenkins for mission-critical software development and testing.
- • Flight software builds
- • Simulation testing
- • Compliance reporting
- • Security scanning
Jenkins Best Practices
✅ Do
- • Use Pipeline as Code (Jenkinsfile)
- • Implement proper error handling and retries
- • Use agents for build isolation
- • Archive important artifacts
- • Monitor build performance metrics
- • Use parallel execution for faster builds
- • Implement proper security and access controls
❌ Don't
- • Run builds on the master node
- • Store secrets in plain text
- • Create overly complex pipelines
- • Ignore build failures
- • Skip backup strategies
- • Overcomplicate with too many plugins
- • Neglect build performance optimization