Epoch 9: Dockerize All Services

Objectives

• Understand how Docker works for packaging NodeJS apps.
• Create Dockerfiles for each microservice (User, Product, Order, Notification, API Gateway).
• Set up a docker-compose.yml file to orchestrate all containers.
• Enable inter-service communication using Docker Compose networking.
• Test that services work seamlessly in a containerized environment.

1. Create Dockerfiles

Create a Dockerfile in each service directory (e.g., user-service/, product-service/, etc.).

# Base image
FROM node:18

# Working directory
WORKDIR /app

# Copy files
COPY . .

# Install dependencies
RUN npm install

# Expose port
EXPOSE 3001  # Change this per service

# Run the service
CMD ["npm", "run", "dev"]

Make sure each service’s package.json has a “dev” script (e.g., node src/index.js or using nodemon).

2. Update docker-compose.yml

At the root of the project, create a docker-compose.yml file to define and run all services:

version: "3.9"

services:
  user-service:
    build: ./user-service
    ports:
      - "3001:3001"
    environment:
      - MONGO_URL=mongodb://mongo:27017/userdb
    depends_on:
      - mongo

  product-service:
    build: ./product-service
    ports:
      - "3002:3002"
    environment:
      - MONGO_URL=mongodb://mongo:27017/productdb
    depends_on:
      - mongo

  order-service:
    build: ./order-service
    ports:
      - "3003:3003"
    environment:
      - MONGO_URL=mongodb://mongo:27017/orderdb
    depends_on:
      - mongo

  notification-service:
    build: ./notification-service
    ports:
      - "3004:3004"

  api-gateway:
    build: ./api-gateway
    ports:
      - "3000:3000"
    depends_on:
      - user-service
      - product-service
      - order-service
      - notification-service

  mongo:
    image: mongo:6.0
    ports:
      - "27017:27017"
    volumes:
      - mongo-data:/data/db

volumes:
  mongo-data:

Note: Use environment variables like MONGO_URL inside each service’s code (.env) to match the Compose setup.

3. Update Service .env Files

Each service should have an .env like:

PORT=3001
MONGO_URL=mongodb://mongo:27017/userdb
JWT_SECRET=your_jwt_secret

Ensure each service listens to 0.0.0.0, not localhost, to allow Docker network access:

app.listen(process.env.PORT || 3001, '0.0.0.0');

4. Run All Services Together

From the project root:

docker-compose up --build

Use –build to rebuild images if the code changes.

To stop:

docker-compose down

5. Verify Everything Works

• Access API Gateway at http://localhost:3000
• Call GET /users, /products, /orders, etc.
• Check logs in each terminal or use:

docker-compose logs -f user-service

6. Docker Folder Structure

ecommerce-microservices/
├── docker-compose.yml
├── .env.example
├── user-service/
│   ├── Dockerfile
│   ├── package.json
│   ├── .env
│   └── src/
├── product-service/
│   ├── Dockerfile
│   ├── package.json
│   ├── .env
│   └── src/
├── order-service/
│   ├── Dockerfile
│   ├── package.json
│   ├── .env
│   └── src/
├── notification-service/
│   ├── Dockerfile
│   ├── package.json
│   └── src/
├── api-gateway/
│   ├── Dockerfile
│   ├── package.json
│   └── src/
└── mongo-data/ (optional volume mapping if not using Docker volume)

6.1 Each Folder Contains

Folder	Purpose
docker-compose.yml	Central file to spin up all services and MongoDB together
user-service/	ExpressJS API for users – has own Dockerfile & Mongo connection
product-service/	Product CRUD service, ready for Redis caching (Epoch 10)
order-service/	Handles order creation and coordination with users/products
notification-service/	Lightweight HonoJS logger or alert receiver
api-gateway/	Central routing layer for external requests
mongo-data/	(Optional) Persistent volume if not using Docker volume

6.2 Sample Dockerfile Recap (for Express-based services)

FROM node:18
WORKDIR /app
COPY . .
RUN npm install
EXPOSE 3001  # Replace per service
CMD ["npm", "run", "dev"]