⚡ How a GitHub Actions Runner Works (Step by Step)

GitHub Actions runners execute workflows when triggered by events like code pushes, pull requests, or scheduled tasks. Here’s a step-by-step breakdown of how it works:

---

🚀 1. Triggering the Pipeline

• You push or pull code to GitHub (or trigger any defined event). 🔄
• GitHub detects this event and assigns the job to an available runner (either GitHub-hosted or self-hosted). 🖥️

📌 Example Triggers:

• push to main branch 📤
• Opening a pull request 🔄
• A cron job running at scheduled times ⏰

---

📥 2. Runner Fetches the Code

• The runner starts on a machine (either a GitHub-provided VM or your own self-hosted server). 🏗️
• It clones (downloads) the latest code from your GitHub repository. 📂
• The runner sets up the working environment as defined in the YAML workflow file.

---

🛠️ 3. Runner Executes the Steps

• It follows the instructions defined in the GitHub Actions YAML file (.github/workflows/your-workflow.yml).
• Each step is executed in the specified order.

📌 Example Steps: ✅ Set up Node.js 🔧
✅ Install dependencies (e.g., npm install) 📦
✅ Run tests (e.g., npm test) 🧪
✅ Build the project (e.g., npm run build) 🏗️
✅ Lint and format code (e.g., eslint . --fix) 🎨

---

📡 4. Deploying to Another Server (Optional Step)

• The runner itself does not run your application; it only executes tasks like testing, building, and deploying.
• If your YAML file includes an SSH step, the runner will:
  • 🔑 Use SSH to connect to the production server.
  • 📤 Copy the built files to the production server using rsync or scp.
  • 🔄 Restart services (e.g., pm2 restart app, docker-compose up -d).

---

🎯 Key Takeaways

✅ GitHub Actions automates testing, building, and deployment processes.
✅ Runners execute jobs based on YAML workflow instructions.
✅ Self-hosted runners provide more control, while GitHub-hosted runners are managed automatically.
✅ Deployments often involve SSH & file transfers to production environments.

💡 With GitHub Actions, you can automate your entire CI/CD pipeline effortlessly! 🚀🔥

---

📜 GitHub Actions CI/CD Pipeline with Deployment

🛠️ Prerequisites:

Before running the pipeline, you must store your server’s private key securely in GitHub:

1. Go to your GitHub Repository → Settings → Actions → Secrets and Variables.
2. Add a new secret with the name DOCUMENT_UBUNTU_SERVER.

---

📌 GitHub Actions Workflow YAML

name: GitHub Action push-based CI/CD Pipeline

on:
  push:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest  ## Replace with self-hosted runner if needed

    steps:
      - name: Checkout code
        uses: actions/checkout@v3

      - name: Use Node.js 22
        uses: actions/setup-node@v3
        with:
          node-version: 22

      - name: Install dependencies
        run: npm install -f

      - name: Build project
        run: npm run build

      - name: Setup SSH Key
        run: |
          mkdir -p ~/.ssh
          echo "${{ secrets.DOCUMENT_UBUNTU_SERVER }}" | tr -d '\r' > ~/.ssh/id_rsa
          chmod 600 ~/.ssh/id_rsa
          ssh-keyscan -H 13.201.191.75 >> ~/.ssh/known_hosts

      - name: Deploy build files to EC2
        run: |
          rsync -avz --delete -e "ssh -i ~/.ssh/id_rsa -o StrictHostKeyChecking=no" ./build/ root@13.201.191.75:/var/www/html/my-docs/build/

---

🔍 Explanation of Each Step:

1. Checkout Code: Pulls the latest code from GitHub.
2. Set Up Node.js: Uses version 22 for the project.
3. Install Dependencies: Ensures all required packages are installed.
4. Build Project: Runs the build command.
5. Setup SSH Key:
   • Stores the private key securely.
   • Adds the remote server to known_hosts to prevent SSH confirmation prompts.
6. Deploy to EC2:
   • Uses rsync to copy the build files securely to the production server.

---

🚀 Final Thoughts

✅ Automates deployment with every push to main.
✅ Secures SSH access with GitHub Secrets .
✅ Ensures seamless deployments by syncing only necessary files.

💡 With this setup, you achieve a fully automated, secure, and efficient CI/CD pipeline! 🔥🔥