GitHub Integration with Jenkins on AWS EC2 (with Webhooks + Error Fixes)

Step 1: Install Java (Required for Jenkins)

sudo apt update
sudo apt install -y openjdk-17-jdk
java -version

Step 2: Install Jenkins

curl -fsSL https://pkg.jenkins.io/debian/jenkins.io-2023.key | sudo tee \
  /usr/share/keyrings/jenkins-keyring.asc > /dev/null

echo "deb [signed-by=/usr/share/keyrings/jenkins-keyring.asc] \
  https://pkg.jenkins.io/debian binary/" | sudo tee \
  /etc/apt/sources.list.d/jenkins.list > /dev/null

sudo apt update
sudo apt install -y jenkins
sudo systemctl start jenkins
sudo systemctl enable jenkins

Step 3: Access Jenkins Web Interface

Visit: http://<your-ec2-ip>:8080

Get the unlock password:

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

• Install Suggested Plugins
• Create Admin User

Step 4: Set Up SSH Access from Jenkins to GitHub

sudo su - jenkins

Generate SSH Key:

ssh-keygen -t ed25519 -C "jenkins@ec2"
# Press enter for defaults
cat ~/.ssh/id_ed25519.pub

Add Public Key to GitHub:

• GitHub > Profile > Settings > SSH and GPG keys
• Add a new key → Paste the public key

Trust GitHub Host:

ssh-keyscan github.com >> ~/.ssh/known_hosts

Test SSH:

ssh -T git@github.com

Exit:

exit

Step 5: Create Jenkins Job

• Go to New Item → Pipeline
• Under Source Code Management:
• Choose: Git
• URL: git@github.com:username/repo.git(Your Github Repo URL)
• Under Build Triggers:
• ✅ Check: GitHub hook trigger for GITScm polling
• Under Pipeline:
• Select the Pipeline script from SCM
• Add Repo URL
• Add credential (Private key SSH)
• Save the job

Step 6: Set Up GitHub Webhook

1. Go to your GitHub Repo → Settings → Webhooks → Add Webhook
2. Fill in:
   • Payload URL:
     http://<your-ec2-ip>:8080/github-webhook/
   • Content type: application/json
   • Events: Just the push event
   • Click Add Webhook

Step 7: Test It!

• Push code to your GitHub repo.
• Check Jenkins if the job triggers.

Troubleshooting Errors & Fixes

❌ Error: No ED25519 host key is known for github.com

Fix:

sudo su - jenkins
ssh-keyscan github.com >> ~/.ssh/known_hosts
exit

Webhook Error: 404 Not Found

Cause: Wrong webhook URL.
✅ Fix: Use: http://<your-ec2-ip>:8080/github-webhook/

❌ Webhook Error: 403 Forbidden or Connection Refused

Cause: Jenkins is not accessible from GitHub.
✅ Fixes: Open port 8080 in EC2 security group.