jenkins-github-ec2-demo

This demo will help you to understand how code is getting deployed to ec2 instance/server Here’s a beginner‑friendly, step‑by‑step guide to set up a Jenkins Pipeline that checks out your GitHub code and deploys it to your EC2 Linux instance over SSH.

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1. Prerequisites

1. Jenkins running in Docker on your local / running on AWS instance.
2. EC2 Linux instance reachable from your local via SSH (you have the .pem key).
3. GitHub repository URL containing your sample code.
4. SSH Agent Plugin installed in Jenkins (we’ll install it below).

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2. Prepare Your EC2 Instance

On your local terminal, ensure you can SSH into the EC2:

ssh -i /path/to/your-key.pem [email protected]

If that works, move on.

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3. Configure Jenkins for SSH Deployments

1. Open Jenkins UI
   Navigate to http://localhost:8080 in your browser.

2. Install SSH Agent Plugin

   • Manage Jenkins → Manage Plugins → Available
   • Search “SSH Agent Plugin”, check it, and click Install without restart.

3. Add SSH Credentials

   • Manage Jenkins → Credentials → System → Global credentials (unrestricted) → Add Credentials
     • Kind: SSH Username with private key
     • Username: ec2-user (or your EC2 user)
     • Private Key: Enter directly → paste the contents of your .pem file
     • ID: ec2-deploy-key (you’ll reference this in the pipeline)
     • Description: “EC2 deploy key”

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4. Create a Jenkins Pipeline Job

1. New Item → “my‑deploy‑pipeline” → Pipeline → OK
2. Under Pipeline section:
   • Definition: Pipeline script from SCM
   • SCM: Git
     • Repository URL: https://github.com/your‑username/your‑repo.git
     • Credentials: (if private) add GitHub credentials the same way you added SSH, or use “None” for public repo
   • Script Path: Jenkinsfile (we’ll create this next)
3. Save the job.

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5. Write Your Jenkinsfile

In the root of your GitHub repo, create a file named Jenkinsfile with the following declarative pipeline:

pipeline {
  agent any

  environment {
    // reference the SSH credential you added
    EC2_SSH = 'ec2-deploy-key'
    // remote host details
    REMOTE_USER = 'ec2-user'
    REMOTE_HOST = 'ec2-your-ip.compute.amazonaws.com'
    // path on the server where code will live
    REMOTE_DIR  = '/home/ec2-user/deploy-demo'
  }

  stages {
    stage('Checkout') {
      steps {
        // clone your GitHub repo
        checkout scm
      }
    }

    stage('Build') {
      steps {
        // (optional) build commands, e.g. npm install, mvn package, etc.
        echo "Add build steps here if needed"
      }
    }

    stage('Deploy to EC2') {
      steps {
        // wraps the following steps in SSH agent
        sshagent (credentials: ["${EC2_SSH}"]) {
          // create target dir, copy code, restart service
          sh """
            ssh -o StrictHostKeyChecking=no ${REMOTE_USER}@${REMOTE_HOST} 'mkdir -p ${REMOTE_DIR}'
            scp -o StrictHostKeyChecking=no -r * ${REMOTE_USER}@${REMOTE_HOST}:${REMOTE_DIR}
            ssh ${REMOTE_USER}@${REMOTE_HOST} 'cd ${REMOTE_DIR} && ./deploy.sh'
          """
        }
      }
    }
  }

  post {
    success {
      echo 'Deployment succeeded!'
    }
    failure {
      echo 'Deployment failed. Check logs.'
    }
  }
}

Notes on the Pipeline

• sshagent: makes your SSH key available inside the sh block.
• StrictHostKeyChecking=no: skips the “yes/no” prompt on first SSH.
• deploy.sh: a simple script in your repo’s root that you write to start/restart your app.

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6. Create a Simple deploy.sh in Your Repo

In your repo root, add:

#!/bin/bash
# deploy.sh – runs on EC2

# Navigate and restart
cd "$(dirname "$0")" || exit
# e.g., if it’s a Node app:
# pm2 stop myapp || true
# pm2 start app.js --name myapp

echo "Deployed at $(date)" >> deploy.log

Make it executable:

chmod +x deploy.sh
git add deploy.sh
git commit -m "Add deploy script"
git push

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7. Run the Pipeline

1. In Jenkins → your “my‑deploy‑pipeline” job → Build Now.
2. Watch the console output:
   • Checkout → Build → Deploy to EC2
   • You should see SSH connection logs and your deploy.sh output.

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8. Verify on EC2

SSH into EC2 again and check:

cat /home/ec2-user/deploy-demo/deploy.log

You should see the timestamp line—confirming your code was copied and the script ran.

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9. Next Steps & Tips

• Security: consider adding your EC2 host to known hosts in Jenkins (ssh-keyscan) instead of disabling StrictHostKeyChecking.
• Scaling: for multiple instances, loop over hosts in the pipeline.
• Credentials: for private GitHub repos, add Git credentials (username/password or SSH key) to Jenkins.
• Notifications: add email/Slack notifications in the post block.

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You’re now set up with a Jenkins Pipeline that takes code from GitHub and deploys it to your EC2 instance! Feel free to tweak the Build and Deploy stages to suit your application’s needs.