🚀 Sample Jenkins CI with Jenkinsfile

This repository provides a comprehensive walkthrough for setting up Jenkins on Google Cloud Platform (GCP) and integrating it with a GitHub repository containing a Jenkinsfile.

Whether you’re new to Jenkins or GCP, this guide will help you set up a working Continuous Integration (CI) pipeline quickly.

---

✅ Prerequisites

Before starting, ensure you have:

• A Google Cloud account with Compute Engine enabled.
• A GitHub account.
• Basic knowledge of Linux commands.
• A sample GitHub repository with some Java code (or any language) and a Jenkinsfile.

---

📝 Step-by-Step Setup

Step 1: Create a Sample GitHub Repository

1. Go to GitHub → create a new repository. Example: sample-jenkinsci-with-jenkinsfile.
2. Add some sample Java (or Python/Node) code. Example: HelloWorld.java.
3. Create a file named Jenkinsfile at the root of the repo with a minimal pipeline:

pipeline {
    agent any

    stages {
        stage('Build') {
            steps {
                echo 'Building the project...'
            }
        }
        stage('Test') {
            steps {
                echo 'Running tests...'
            }
        }
        stage('Deploy') {
            steps {
                echo 'Deploying application...'
            }
        }
    }
}

✅ Ensure the filename is exactly Jenkinsfile (case-sensitive).

---

Step 2: Create a VM on GCP & Install Jenkins

1. Go to GCP Console → Compute Engine → VM Instances → Create Instance.

   • Name: jenkins-ci
   • Machine type: e2-medium (2 vCPUs, 4GB RAM)
   • Boot disk: Ubuntu 22.04 LTS
   • Allow HTTP & HTTPS traffic

2. SSH into VM and install Jenkins. You can follow this guide 👉 Jenkins Setup and Installation.

---

Step 3: Access Jenkins UI

1. Get VM External IP from GCP.

2. Open in browser:

   http://<external-ip>:8080
   

3. Unlock Jenkins:

   sudo cat /var/lib/jenkins/secrets/initialAdminPassword

4. Install suggested plugins and create an Admin user.

---

Step 4: Create a New Pipeline Job in Jenkins

1. Go to Jenkins Dashboard → Click New Item.
2. Enter job name: first-pipeline-job-with-jenkinsfile.
3. Select Pipeline → Click OK.

---

Step 5: Configure GitHub Repository in Jenkins

1. In job configuration → Scroll to Pipeline section.

2. Set Definition → Pipeline script from SCM.

3. SCM → Select Git.

4. Enter your GitHub Repository URL. Example:

   https://github.com/<your-username>/sample-jenkinsci-with-jenkinsfile.git
   

5. If repo is private → click Add Credentials → provide GitHub username & token.

---

Step 6: Configure Branch & Script Path

1. Scroll to Branches to build section.

   • Branch Specifier: main (or master, depending on your repo).

2. Scroll to Script Path → set as Jenkinsfile.

⚠️ Important: The filename in GitHub and Script Path must match exactly (case-sensitive).

---

Step 7: Save & Build

1. Click Save.
2. Go to job dashboard → Click Build Now.
3. Open Console Output → Jenkins will show logs of each stage (Build, Test, Deploy).

---

Step 8: Verify Build Status

• ✅ SUCCESS → All stages executed properly.
• ❌ FAILURE → Build or Test step failed.
• ⚠️ UNSTABLE → Build successful but some tests failed.

---

🎯 Final Result

You now have a Jenkins CI Pipeline on GCP VM that:

• Pulls code from GitHub.
• Runs Build, Test, Deploy stages via Jenkinsfile.
• Can auto-trigger builds using webhooks or pollSCM configuration.

---