Customization

LLM API Gateway Routing Rules

Complete guide to implementing intelligent routing rules for LLM API Gateway. Learn traffic splitting, A/B testing, canary deployments, geographic routing, and advanced routing strategies.

🛣️

Routing Overview

API Gateway routing rules determine how incoming requests are directed to different backend services. This enables advanced deployment strategies, traffic management, and personalized user experiences.

Traffic Flow Visualization

📥
Client
→
🔀
Gateway
→
🚀
v2.0
80%
→
🧪
v3.0
20%

Why Use Routing Rules?

  • Zero-Downtime Deployments: Gradually shift traffic to new versions
  • A/B Testing: Test new features with a subset of users
  • Geographic Routing: Route users to nearest servers
  • Load Balancing: Distribute traffic across multiple backends
  • Feature Flags: Enable features for specific user segments
📋

Routing Rule Types

Here are the most common routing rule types for LLM API Gateway:

🔗 Path-Based

Route based on URL path patterns.

/api/v1/* → backend-v1 /api/v2/* → backend-v2

📝 Header-Based

Route based on HTTP headers.

X-Client: web → web-backend X-Client: mobile → mobile-backend

❓ Query-Based

Route based on query parameters.

?model=gpt-4 → premium ?model=gpt-3.5 → standard

⚖️ Weighted

Split traffic by percentage.

backend-a: 80% backend-b: 20%

🌍 Geographic

Route by user location.

US → us-east EU → eu-west APAC → ap-south

👤 User-Based

Route by user attributes.

tier: premium → premium-backend tier: free → free-backend
⚙️

Implementation Guide

Basic Routing Configuration

Set up routing rules in your API Gateway configuration:

// routing-config.js
const routingRules = [
    // Path-based routing
    {
        path: '/api/chat/*',
        backend: 'chat-service:8001',
        methods: ['POST', 'GET']
    },
    // Header-based routing
    {
        headers: { X-Client-Type: 'mobile' },
        backend: 'mobile-service:8002'
    },
    // Query-based routing
    {
        query: { model: 'gpt-4' },
        backend: 'premium-service:8003',
        priority: 10
    }
];

// Export routing rules
module.exports = routingRules;

Traffic Splitting Implementation

Implement weighted routing for canary deployments:

const weightedRouting = (req) => {
    // Generate consistent hash for user session
    const sessionId = req.headers['x-session-id'] || generateId();
    const hash = murmurHash(sessionId) % 100;
    
    // Traffic split: 80% stable, 20% canary
    if (hash < 80) {
        return 'stable-backend:8001';
    } else {
        return 'canary-backend:8002';
    }
};

// Apply weighted routing
app.use(async (req, res, next) => {
    const backend = weightedRouting(req);
    req.backend = backend;
    next();
});

Best Practices

  • Always have a default route for unmatched requests
  • Use consistent hashing for user-level traffic splitting
  • Monitor both old and new versions during canary deployments
  • Implement automatic rollback if error rates increase
  • Document routing rules and their purposes
  • Test routing rules in staging before production