How can I use CDN and API gateway services to protect public endpoints and route traffic globally?

Using a CDN and an API gateway together is a common pattern for protecting public endpoints and routing traffic efficiently worldwide.

Typical flow

Client → CDN edge → API gateway → backend services

1) Put the CDN in front of everything

A CDN sits at the edge of the internet and can:

• Cache static content close to users
• Absorb traffic spikes
• Provide DDoS protection
• Enforce WAF rules and bot protection
• Hide your origin IPs by only exposing the CDN

For public APIs, the CDN can also proxy requests, even if it does not cache them heavily.

2) Use the API gateway as the controlled entry point

The API gateway handles:

• Authentication and authorization
• Rate limiting / throttling
• Request validation
• Routing to the right service
• Versioning and path-based routing
• Logging, tracing, and analytics

This means external clients never talk directly to your internal services.

3) Route globally

To support global traffic:

• Use the CDN’s Anycast network so users connect to the nearest edge
• Use geo-based routing or latency-based routing to send traffic to the closest healthy region
• Deploy your API gateway in multiple regions
• Place backends behind regional load balancers
• Use failover policies so traffic shifts automatically if a region is unhealthy

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Security best practices

Hide the origin

• Lock down the API gateway so it only accepts traffic from the CDN
• Use IP allowlists, mTLS, or signed headers/tokens between CDN and gateway
• Prevent direct access to the origin hostname

Add edge protection

At the CDN layer, enable:

• DDoS mitigation
• Web Application Firewall
• Bot filtering
• TLS termination
• Optional request size limits and geo restrictions

Protect the API layer

At the gateway, enforce:

• OAuth2/OIDC/JWT validation
• API keys if appropriate
• Per-client and per-route rate limits
• Schema validation and method restrictions

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Routing patterns

Static + API on the same domain

Example:

• www.example.com → CDN cache for static assets
• api.example.com → CDN proxy to API gateway

This keeps the public surface simple.

Path-based routing

Example:

• /assets/* → cached at CDN
• /api/* → forwarded to API gateway

Useful if you want a single domain.

Multi-region active-active

• CDN routes users to nearest region
• Each region has its own gateway and backend stack
• If one region fails, traffic goes to another region

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Cache carefully

For API traffic:

• Cache only safe, idempotent, public GET responses
• Use proper cache-control headers
• Include query string and header rules in cache keys where needed
• Never cache user-specific or sensitive responses unless explicitly designed for it

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Example architecture

1. User requests api.example.com
2. CDN terminates TLS and applies WAF/rate limits
3. CDN forwards request to nearest healthy regional API gateway
4. API gateway authenticates the request and applies throttling
5. Gateway routes to backend service in that region
6. Response returns through gateway and CDN to the client

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Benefits

• Reduced latency for users worldwide
• Better resilience during spikes or attacks
• Smaller attack surface
• Centralized API governance
• Lower load on origin services

If you want, I can also give you:

1. a cloud-agnostic reference architecture, or
2. a provider-specific example for AWS, Azure, or Google Cloud.