How do you create a pipeline in Jenkins?

Question

Accepted Answer

Creating a Jenkins pipeline means defining the build, test, and deploy stages as code in a Jenkinsfile, which Jenkins executes automatically whenever changes are detected in the source repository.

Key Points:
• Create a new Jenkins job and choose the "Pipeline" project type rather than a legacy freestyle job.
• Define the pipeline using declarative or scripted syntax in a Jenkinsfile, checked into the project's repository as pipeline-as-code.
• Stages typically include checkout, build, test, and deploy, each containing one or more steps such as shell commands.
• Jenkins can trigger the pipeline via SCM polling or, more commonly, a webhook fired on every push or pull request.
• Pipeline runs are visualized stage-by-stage in the Jenkins UI (or Blue Ocean), making it easy to spot where a failure occurred.

Example:
A team adds a Jenkinsfile to the repo root with build, test, and deploy stages; after connecting a GitHub webhook, every push to main automatically triggers Jenkins to run mvn verify and then deploy the resulting artifact.

Code Example:
```
pipeline {
    agent any
    stages {
        stage('Checkout') { steps { checkout scm } }
        stage('Build')    { steps { sh 'mvn clean package' } }
        stage('Test')     { steps { sh 'mvn test' } }
        stage('Deploy')   { steps { sh './deploy.sh' } }
    }
}
```

Interview Tip:
A concise interview answer is:

"I create a Pipeline job in Jenkins and define the stages in a Jenkinsfile checked into the repo, using declarative syntax for checkout, build, test, and deploy steps. Jenkins then triggers that pipeline automatically via a webhook whenever code is pushed."