Complete Jenkins Tutorial
What Is Jenkins?
Jenkins is the industry-standard automation server for continuous integration and delivery — it builds, tests, and deploys code automatically. For testers, it's how automation suites run on every commit and nightly. This guide covers Jenkins end to end, from CI/CD concepts to distributed builds and the REST API.
Part 1 — Foundations
- Fundamentals & CI/CD Concepts — what Jenkins is, features, and CI vs CD vs Continuous Deployment.
- Freestyle vs Pipeline & Job Configuration — job types, configuration, and build triggers.
- CRON Scheduling & Build Triggers — CRON syntax, Build Periodically, and Poll SCM vs webhooks.
Part 2 — Pipelines & Integration
- Pipelines & Jenkinsfile — declarative vs scripted, stages, post, and parallel execution.
- Git Integration & Webhooks — Git plugin, credentials, and GitHub webhooks.
- Build, Deployment & Maven — Maven integration, pom.xml, artifacts, and deployment.
Part 3 — Operations
- Plugins, Notifications & Monitoring — key plugins, email/Slack alerts, and job monitoring.
- Security, Administration, Distributed Builds & REST API — users/roles, backup, master-agent, and the REST API.
How to Use This Guide
- Beginners: Parts 1 → 3 in order.
- Pipeline focus: Part 2 (Jenkinsfile, Git, Maven).
- Interview prep: fundamentals, freestyle vs pipeline, and CRON are the most-asked.
Pair with the Complete Selenium Guide (Maven/CI-CD tutorial) and REST Assured Guide for running automation in CI.
Frequently Asked Questions
What is Jenkins used for?
Jenkins automates software build, testing, and deployment activities as part of Continuous Integration and Continuous Delivery pipelines.
For testers, Jenkins is commonly used to execute automation suites on every code commit or on scheduled intervals.
What is the difference between Freestyle and Pipeline?
Freestyle Jobs are configured using the Jenkins graphical interface.
Pipeline Jobs are defined as code using a Jenkinsfile, making them version-controlled, reusable, and easier to maintain.
What is the difference between CI, Continuous Delivery, and Continuous Deployment?
- Continuous Integration (CI) automatically builds and tests code after integration.
- Continuous Delivery (CD) prepares software for release while allowing manual approval before deployment.
- Continuous Deployment automatically deploys verified code directly into production.
Should I use Webhooks or Poll SCM?
Webhooks are event-driven and trigger builds immediately after code changes.
Poll SCM checks the repository at scheduled intervals and is typically used when webhooks cannot be configured.
How do you trigger a Jenkins job using the REST API?
A Jenkins job can be triggered by sending a POST request to the appropriate job endpoint (/build or /buildWithParameters) using a valid username and API token.