Introduction to Jenkins and CI/CD

What is Jenkins?

Jenkins is the most widely used open-source automation server. It helps you build, test and deploy software continuously. Whatever your tooling - Maven, Gradle, Docker, npm, shell scripts - Jenkins orchestrates it on a schedule or on every code change.

What Is CI/CD?

• CI (Continuous Integration) - developers merge code often; every push is built and tested automatically so integration problems surface within minutes, not days.
• CD (Continuous Delivery) - every change that passes the build can be released to staging automatically, ready to be deployed.
• Continuous Deployment - the pipeline also deploys to production automatically without human approval.

How Jenkins Works

A Jenkins job (or pipeline) runs on the Jenkins master or on connected agents. Each run produces artifacts (WARs, jars, reports) and a console log you can inspect from the web UI.

Typical Pipeline Stages

checkout  ->  compile  ->  test  ->  package  ->  deploy

Failures stop the pipeline early, and notifications (email, Slack) tell the team exactly which change broke the build.

Key Points

• Jenkins automates build, test and deploy so humans review, not repeat.
• CI means merging early and testing every change automatically.
• Pipelines are configuration-as-code: the pipeline lives in the repository.