Express

API Gateway with Node.js and Express

In Sprint 4, we implemented an API Gateway using Node.js and Express, which acts as the entry point for all microservices.

// Example of an API Gateway with Express
const express = require('express');
const { createProxyMiddleware } = require('http-proxy-middleware');
const jwt = require('jsonwebtoken');

const app = express();
const PORT = process.env.PORT || 80;
const SECRET_KEY = process.env.JWT_SECRET_KEY || '4Z^XrroxR@dWxqf$!@#qGr4P';
const ISSUER = process.env.JWT_ISSUER || 'user-api';

// Middleware to validate JWT
const validateJwt = (req, res, next) => {
    const token = req.headers['authorization']?.split(' ')[1];

    if (!token) {
        return res.status(401).json({ message: 'Token not provided' });
    }

    try {
        const decoded = jwt.verify(token, SECRET_KEY, { issuer: ISSUER });
        req.user = decoded.user;
        next();
    } catch (error) {
        return res.status(401).json({ message: 'Invalid token' });
    }
};

// Proxy event configuration
const proxyEvents = {
    proxyReq: (proxyReq, req, res) => {
        if (req.user) {
            proxyReq.setHeader('x-user', JSON.stringify(req.user));
        }
    }
};

// Public routes (without authentication)
app.use('/auth', createProxyMiddleware({
    target: 'http://usermanagement:8080',
    changeOrigin: true,
    pathRewrite: { '^/auth': '/auth' },
    logger: console
}));

// Authentication middleware for protected routes
app.use(validateJwt);

// Protected routes
app.use('/users', createProxyMiddleware({
    target: 'http://usermanagement:8080',
    changeOrigin: true,
    pathRewrite: { '^/users': '/users' },
    on: proxyEvents,
    logger: console
}));

app.use('/requests', createProxyMiddleware({
    target: 'http://feedbackrequest:8082',
    changeOrigin: true,
    pathRewrite: { '^/requests': '/requests' },
    on: proxyEvents,
    logger: console
}));

app.use('/responses', createProxyMiddleware({target: 'http://feedbackresponse:8081',
    changeOrigin: true,
    pathRewrite: { '^/responses': '/responses' },
    on: proxyEvents,
    logger: console
}));

app.use('/responsesview', createProxyMiddleware({
    target: 'http://feedbackresponseview:8000',
    changeOrigin: true,
    pathRewrite: { '^/responsesview': '/responsesview' },
    on: proxyEvents,
    logger: console
}));

// Middleware to handle not found routes
app.use((req, res) => {
    res.status(404).json({ message: 'Route not found' });
});

// Start the server
app.listen(PORT, () => {
    console.log(`API Gateway running on port ${PORT}`);
});