Demo Pipeline Script from SCM

In this tutorial, we’ll demonstrate how to source your Jenkins pipeline definition directly from a Source Control Management (SCM) system such as GitHub or Gitea. Moving your pipeline code into version control improves maintainability, traceability, and collaboration.

1. Inline Pipeline Definition (Not Recommended)

Defining a pipeline directly in the Jenkins UI is quick but hard to maintain. Changes aren’t versioned, and collaboration is limited.

Warning

Avoid storing pipeline scripts in the UI. Inline definitions lack versioning and code review.

pipeline {
  agent any
  tools {
    maven 'M398'
  }
  stages {
    stage('Echo Version') {
      steps {
        sh 'echo Print_Maven_Version'
        sh 'mvn -version'
      }
    }
    stage('Build') {
      steps {
        // Fetch source code
        git 'http://139.84.159.194:5555/dasher-org/jenkins-hello-world.git'
        // Package with Maven
        // sh 'mvn clean package -DskipTests=true'
      }
    }
    stage('Unit Test') {
      steps {
        sh 'mvn test'
      }
    }
  }
}

2. Creating a Jenkinsfile in Your Repository

Store your pipeline script as a Jenkinsfile at the root of your project repository:

Navigate to your app repo on GitHub or Gitea.
Click Add file → Create new file.
Name it Jenkinsfile.
Paste the pipeline script and commit to main.

pipeline {
  agent any
  tools {
    // Installs Maven configured as "M398"
    maven "M398"
  }
  stages {
    stage('Echo Version') {
      steps {
        sh 'echo Print Maven Version'
        sh 'mvn -version'
      }
    }
    stage('Build') {
      steps {
        // Auto-checkout not yet enabled
        git 'http://139.84.159.194:5555/dasher-org/jenkins-hello-world.git'
        sh 'mvn clean package -DskipTests=true'
      }
    }
    stage('Unit Test') {
      steps {
        sh 'mvn test'
      }
    }
  }
}

3. Simplifying the Jenkinsfile

Once Jenkins auto-checks out your code, remove the explicit git step to simplify:

Note

Jenkins automatically clones the repository when using Pipeline script from SCM.

pipeline {
  agent any
  tools {
    maven "M398"
  }
  stages {
    stage('Echo Version') {
      steps {
        sh 'echo Print Maven Version'
        sh 'mvn -version'
      }
    }
    stage('Build') {
      steps {
        // Repository checked out automatically
        sh 'mvn clean package -DskipTests=true'
      }
    }
    stage('Unit Test') {
      steps {
        sh 'mvn test'
      }
    }
  }
}

4. Configuring “Pipeline script from SCM”

In Jenkins:

Create (or open) a Pipeline job.
Under Pipeline > Definition, select Pipeline script from SCM.
Choose Git and enter your repository details:

Field	Value
Repository URL	`http://139.84.159.194:5555/dasher-org/jenkins-hello-world.git`
Branch Specifier	`main`
Script Path	`Jenkinsfile`

If the URL is missing or invalid, Jenkins displays an error:

The image shows a Jenkins configuration screen for a pipeline, where a Git repository URL is being entered, but there's an error message indicating the need to enter a valid Git repository.

Save the job and click Build Now.

5. Observing Automatic Checkout and Build

When the pipeline runs, Jenkins adds a Checkout SCM stage:

The image shows a Jenkins dashboard displaying the status of a "hello-world-pipeline" with various stages like "Checkout SCM," "Tool Install," "Build," and "Unit Test." It includes a build history with different pipeline runs, some of which have failed stages.

Console Output Highlights

> git rev-parse --resolve-git-dir /var/lib/jenkins/workspace/hello-world-pipeline/.git # timeout=10
> git config remote.origin.url http://139.84.159.194:5555/dasher-org/jenkins-hello-world.git # timeout=10
> git fetch origin +refs/heads/*:refs/remotes/origin/* # timeout=10
> git checkout -f origin/main # timeout=10

echo Print Maven Version
mvn --version

Apache Maven 3.9.8 (36645f6c9b5079805ea5009217e36cff344256)
Maven home: /var/lib/jenkins/tools/hudson.tasks.Maven_MavenInstallation/M398
Java version: 17.0.12, vendor: Ubuntu
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "6.8.0-39-generic", arch: "amd64"

6. Browsing the Repository in Your SCM

Verify your Jenkinsfile and project files in the web UI:

The image shows a code repository interface for a project named "jenkins-hello-world" with a list of files and recent commit messages. The README section describes it as a "Springboot Hello World App" used for a Jenkins training demo.

7. Exploring the Jenkins Workspace

Click Workspace in the job sidebar to view checked-out files and build artifacts:

The image shows a Jenkins workspace interface displaying a list of directories and files related to a project build, including JAR files and source folders.

8. Reviewing Completed Build Details

Inspect completed builds and each pipeline stage:

The image shows a Jenkins build pipeline interface, displaying the status and details of a completed build process with various stages like "Checkout SCM," "Tool Install," and "Unit Test."

9. Inspecting Jenkins Home and Workspaces on the Controller

Access your Jenkins controller via SSH to list directories:

# View Jenkins home directory
cd /var/lib/jenkins
ls -l

# List job workspaces
cd workspace/
ls -l

# Inspect hello-world-pipeline workspace
cd hello-world-pipeline
ls -l

That’s it! You’ve learned how to manage your Jenkins pipeline script in SCM, run builds, and explore both the SCM repo and Jenkins workspace.