Objectives

1. Add Redis to Docker Compose

Update your root docker-compose.yml to include a Redis container:

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services:
  redis:
    image: redis:7-alpine
    container_name: redis
    ports:
      - "6379:6379"

Make sure product-service depends on it:

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product-service:
  build: ./product-service
  ports:
    - "3002:3002"
  environment:
    - MONGO_URL=mongodb://mongo:27017/productdb
    - REDIS_URL=redis://redis:6379
  depends_on:
    - mongo
    - redis

2. Install Redis Client

Inside product-service:

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npm install ioredis

3. Configure Redis Connection

Inside product-service/src/config/redis.js:

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const Redis = require('ioredis');
const redis = new Redis(process.env.REDIS_URL);
module.exports = redis;

Load REDIS_URL=redis://redis:6379 from .env.

4. Implement Caching in Product Controller

Here’s how to cache GET /products:

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const redis = require('../config/redis');
const Product = require('../models/Product');

// GET /products
const getAllProducts = async (req, res) => {
  try {
    // Check cache first
    const cached = await redis.get('products');
    if (cached) {
      return res.status(200).json(JSON.parse(cached));
    }

    // If not cached, query DB
    const products = await Product.find();

    // Cache result for 1 hour
    await redis.set('products', JSON.stringify(products), 'EX', 3600);

    res.status(200).json(products);
  } catch (err) {
    res.status(500).json({ message: 'Server error' });
  }
};

5. Invalidate Cache on Update/Delete

Update or delete actions must clear or refresh the cache:

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// After update/delete:
await redis.del('products');

Or, if updating a specific product:

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await redis.del(`product:${productId}`);

Cache Individual Products (Optional)

For GET /products/:id, cache per product:

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const cached = await redis.get(`product:${id}`);
if (cached) return res.json(JSON.parse(cached));

const product = await Product.findById(id);
await redis.set(`product:${id}`, JSON.stringify(product), 'EX', 3600);