Chapter 10: Jenkins Introduction
10.2 Controller, agents and jobs
| Word | Meaning | Real-world picture |
|---|---|---|
| Controller (formerly master) | Orchestrates jobs, serves UI | Head office |
| Agent (node) | Machine that executes build steps | Worker machine that builds |
| Job / item | A configured task (Freestyle or Pipeline) | One configured pipeline job |
| Executor | Slot on an agent that runs one build | One burner |
Freestyle job — clicky UI steps (build commands in form fields). Fine for demos; hard to review in Git.
Pipeline job — logic in a Jenkinsfile committed with the app. Preferred for teams (reviewable, repeatable).
Developer push → Jenkins scans SCM / webhook
→ Controller schedules build
→ Agent checks out code, runs stages
→ Result red/green + logs
You do not need to redesign VPC here. If Jenkins runs on a lab VM, lock SSH and the Jenkins HTTP shop counter with Security Groups the AWS course way — or keep Jenkins bound for localhost + SSH tunnel in early labs.
Ravindra Bagale's Tip
Jenkins public IP var without login — khup dangerous. Lab asel tari auth on theva; preferably localhost/tunnel or tight SG. Dhyan rakho!