CI/CD Pipeline for MERN Using GitHub Actions + Docker (2025 DevOps Guide)

In 2025, if you're building full-stack MERN apps, you're expected to go beyond just npm start. Teams and clients want automation, reliability, and fast delivery.

That’s where CI/CD pipelines come in — and GitHub Actions + Docker is a powerful combo.

---

⚙️ What Is CI/CD?

• CI (Continuous Integration): Automatically test & build your code when changes are pushed.
• CD (Continuous Deployment): Automatically deploy your app after a successful build.

Together, CI/CD brings:

• 🧪 Fewer bugs
• 🚀 Faster releases
• 🔄 Automated workflow

---

🚧 Our Stack for This Pipeline

• GitHub Actions: Automation engine triggered by repo events
• Docker: Containerized deployment of MERN app
• MERN App: Node.js backend, React frontend
• Render or Vercel: For final hosting (optional)

---

🗂️ Project Structure Overview

mern-ci-cd/
├── client/            # React app
├── server/            # Node.js API
├── .github/
│   └── workflows/
│       └── ci-cd.yml  # GitHub Actions config
├── Dockerfile
├── docker-compose.yml
└── README.md

---

🐳 Dockerfile (for Node + React)

# Build React
FROM node:18 as build-frontend
WORKDIR /app/client
COPY client/ .
RUN npm install && npm run build

# Build backend
FROM node:18
WORKDIR /app
COPY server/ ./server
COPY --from=build-frontend /app/client/build ./client/build
COPY package*.json ./
RUN npm install
EXPOSE 5000
CMD ["node", "server/index.js"]

---

🐳 docker-compose.yml

version: "3"
services:
  app:
    build: .
    ports:
      - "5000:5000"
    environment:
      - NODE_ENV=production
      - MONGO_URI=${MONGO_URI}

---

🤖 GitHub Actions Workflow (.github/workflows/ci-cd.yml)

name: MERN CI/CD Pipeline

on:
  push:
    branches:
      - main

jobs:
  build-deploy:
    runs-on: ubuntu-latest

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

      - name: Set up Node.js
        uses: actions/setup-node@v3
        with:
          node-version: "18"

      - name: Install dependencies
        run: npm install

      - name: Build client
        run: |
          cd client
          npm install
          npm run build

      - name: Build Docker Image
        run: docker build -t mern-app .

      - name: Run Tests (optional)
        run: echo "Add test runner here"

      - name: Deploy (e.g. to Render)
        run: echo "Add deploy script or use Render GitHub integration"

---

---

🔐 Secrets You’ll Need (GitHub Repo Settings)

• MONGO_URI
• DOCKER_USERNAME, DOCKER_PASSWORD (optional for Docker Hub)
• RENDER_API_KEY or VERCEL_TOKEN (if using deployment automation)

---

✅ Best Practices

• Use different environments for dev/staging/prod
• Run lint/tests during CI phase
• Tag Docker images using commit SHA or version

---

🧠 Final Thoughts

With this CI/CD pipeline, every push to main:

1. Installs dependencies
2. Builds frontend + backend
3. Builds Docker image
4. Optionally deploys to production

Say goodbye to FTP uploads and manual builds — automate everything like a modern dev!

---

Published on: 2025-06-18