How to build microservices with Replit

1# Create the project structure in Shell
2mkdir -p src/routes src/middleware src/utils
3touch src/index.js
4touch src/routes/users.js
5touch src/routes/products.js
6touch src/routes/orders.js
7touch src/middleware/auth.js
8touch src/middleware/errorHandler.js
9touch src/utils/db.js

1// src/index.js
2const express = require('express');
3const cors = require('cors');
4const { initDatabase } = require('./utils/db');
5const usersRouter = require('./routes/users');
6const productsRouter = require('./routes/products');
7const ordersRouter = require('./routes/orders');
8const errorHandler = require('./middleware/errorHandler');
9
10const app = express();
11const PORT = process.env.PORT || 3000;
12
13// Global middleware
14app.use(cors());
15app.use(express.json());
16
17// Health check
18app.get('/', (req, res) => {
19  res.json({ status: 'healthy', timestamp: new Date().toISOString() });
20});
21
22// Mount route modules
23app.use('/api/users', usersRouter);
24app.use('/api/products', productsRouter);
25app.use('/api/orders', ordersRouter);
26
27// Error handler (must be last)
28app.use(errorHandler);
29
30app.listen(PORT, '0.0.0.0', async () => {
31  await initDatabase();
32  console.log(`API running on 0.0.0.0:${PORT}`);
33});

1// src/routes/products.js
2const express = require('express');
3const { query } = require('../utils/db');
4const router = express.Router();
5
6// GET /api/products
7router.get('/', async (req, res, next) => {
8  try {
9    const result = await query(
10      'SELECT * FROM products ORDER BY created_at DESC LIMIT 50'
11    );
12    res.json(result.rows);
13  } catch (err) {
14    next(err);
15  }
16});
17
18// POST /api/products
19router.post('/', async (req, res, next) => {
20  try {
21    const { name, price, description } = req.body;
22    if (!name || !price) {
23      return res.status(400).json({ error: 'name and price are required' });
24    }
25    const result = await query(
26      'INSERT INTO products (name, price, description) VALUES ($1, $2, $3) RETURNING *',
27      [name, price, description]
28    );
29    res.status(201).json(result.rows[0]);
30  } catch (err) {
31    next(err);
32  }
33});
34
35// GET /api/products/:id
36router.get('/:id', async (req, res, next) => {
37  try {
38    const result = await query(
39      'SELECT * FROM products WHERE id = $1',
40      [req.params.id]
41    );
42    if (result.rows.length === 0) {
43      return res.status(404).json({ error: 'Product not found' });
44    }
45    res.json(result.rows[0]);
46  } catch (err) {
47    next(err);
48  }
49});
50
51module.exports = router;

1// src/middleware/auth.js
2function requireApiKey(req, res, next) {
3  const apiKey = req.headers['x-api-key'];
4  const validKey = process.env.API_KEY;
5
6  if (!validKey) {
7    console.error('API_KEY not configured in Secrets');
8    return res.status(500).json({ error: 'Server configuration error' });
9  }
10
11  if (!apiKey || apiKey !== validKey) {
12    return res.status(401).json({ error: 'Invalid or missing API key' });
13  }
14
15  next();
16}
17
18module.exports = { requireApiKey };
19
20// Usage in index.js:
21// app.use('/api/products', requireApiKey, productsRouter);

1// src/middleware/errorHandler.js
2function errorHandler(err, req, res, next) {
3  console.error(`[${new Date().toISOString()}] Error:`, err.message);
4  console.error('Stack:', err.stack);
5
6  // PostgreSQL constraint violations
7  if (err.code === '23505') {
8    return res.status(409).json({ error: 'Resource already exists' });
9  }
10  if (err.code === '23503') {
11    return res.status(400).json({ error: 'Referenced resource does not exist' });
12  }
13
14  // Default server error
15  res.status(err.status || 500).json({
16    error: process.env.NODE_ENV === 'production'
17      ? 'Internal server error'
18      : err.message
19  });
20}
21
22module.exports = errorHandler;

1# .replit deployment configuration
2[deployment]
3build = ["npm", "install"]
4run = ["node", "src/index.js"]
5deploymentTarget = "cloudrun"
6
7[[ports]]
8localPort = 3000
9externalPort = 80