API Gateway

Port 8000

The Gateway service routes all API requests to their respective microservices using http-proxy-middleware.

---

Overview

Property	Value
Port	8000
Technology	Express.js + http-proxy-middleware
Purpose	API routing, CORS handling

---

Route Configuration

All frontend API calls go through the gateway at http://localhost:8000:

flowchart TB
    subgraph Client
        F[Frontend :5173]
    end

    subgraph Gateway
        G[API Gateway :8000]
    end

    subgraph Services
        A[Auth :3001]
        M[Marketplace :3002]
        R[RentHub :3003]
        N[NewsBox :3004]
        NO[Notices :3005]
        C[Chat :3006]
        I[Issue :3007]
    end

    F -->|/api/*| G
    G -->|/api/auth/*| A
    G -->|/api/market/*| M
    G -->|/api/renthub/*| R
    G -->|/api/newsbox/*| N
    G -->|/api/notices/*| NO
    G -->|/api/chat/*| C
    G -->|/api/issues/*| I

---

Proxy Routes

Gateway Path	Target Service	Service Path
/api/auth/*	http://localhost:3001	/*
/api/market/*	http://localhost:3002	/*
/api/renthub/*	http://localhost:3003	/*
/api/newsbox/*	http://localhost:3004	/*
/api/notices/*	http://localhost:3005/notices	/*
/api/chat/*	http://localhost:3006	/*
/api/issues/*	http://localhost:3007	/*

---

Path Rewriting

The gateway rewrites paths before proxying:

Example: AuthExample: Marketplace

Client request:  GET /api/auth/profile
Gateway strips:  /api/auth
Service receives: GET /profile

Client request:  GET /api/market/vendors?type=FOOD_VENDOR
Gateway strips:  /api/market
Service receives: GET /vendors?type=FOOD_VENDOR

---

Gateway Configuration

// gateway/server.js

// Auth Service Proxy
app.use('/api/auth', createProxyMiddleware({
    target: 'http://localhost:3001',
    changeOrigin: true,
    pathRewrite: {
        '^/api/auth': '',
    }
}));

// Marketplace Service Proxy
app.use('/api/market', createProxyMiddleware({
    target: 'http://localhost:3002',
    changeOrigin: true,
    pathRewrite: {
        '^/api/market': '',
    }
}));

// ... similar for other services

---

CORS Configuration

The gateway handles CORS for all services:

app.use(cors({
    origin: true, // Allow all origins (development)
    credentials: true
}));

Production Configuration

In production, replace origin: true with specific allowed origins:

origin: ['https://edusync.uiu.edu', 'https://www.edusync.uiu.edu']

---

Logging

All requests are logged to both console and gateway.log:

app.use((req, res, next) => {
    log(`${req.method} ${req.url}`);
    next();
});

Log Output

[2024-01-15T10:30:00.000Z] GET /api/auth/profile
[2024-01-15T10:30:00.050Z] → Proxying to Auth Service: GET /profile
[2024-01-15T10:30:05.000Z] POST /api/market/orders
[2024-01-15T10:30:05.050Z] → Proxying to Marketplace Service: POST /orders

---

Error Handling

Each proxy has error handling for unreachable services:

onError: (err, req, res) => {
    log(`❌ Auth Proxy Error: ${err.message}`);
    res.status(500).json({ 
        error: 'Could not reach Auth Service', 
        details: err.message 
    });
}

Error Response

{
    "error": "Could not reach Auth Service",
    "details": "connect ECONNREFUSED 127.0.0.1:3001"
}

---

Health Check

GET /

Returns gateway status.

Response

Gateway is Running

---

Service Dependencies

The gateway should start after all backend services:

flowchart LR
    A[Auth Service] --> G[Gateway]
    M[Marketplace Service] --> G
    R[RentHub Service] --> G
    N[NewsBox Service] --> G
    NO[Notices Service] --> G
    C[Chat Service] --> G
    I[Issue Service] --> G
    G --> F[Frontend]

---

Starting the Gateway

cd gateway
npm install
npm start
# or
node server.js

Expected Output

🚀 Gateway running on http://localhost:8000

---

Testing Gateway Routes

Use curl or any HTTP client:

# Test gateway health
curl http://localhost:8000/

# Test auth service through gateway
curl http://localhost:8000/api/auth/health

# Test marketplace through gateway
curl http://localhost:8000/api/market/vendors

# Test with authentication
curl http://localhost:8000/api/auth/profile \
  -H "Authorization: Bearer YOUR_JWT_TOKEN"

---

Troubleshooting

Common Issues

Issue	Cause	Solution
502 Bad Gateway	Target service down	Start the target service
CORS Error	Origin not allowed	Check CORS configuration
Connection Refused	Wrong port	Verify service ports
Timeout	Service slow/stuck	Check service logs

Debug Mode

Enable verbose logging:

const { createProxyMiddleware } = require('http-proxy-middleware');

createProxyMiddleware({
    target: 'http://localhost:3001',
    logLevel: 'debug', // Enable debug logging
    // ...
});