How do I control and route API traffic from one gateway?

To control and route API traffic from one gateway, you typically put a single API gateway in front of your services and configure it to handle routing, policies, security, and traffic management.

Core idea

Clients call the gateway, and the gateway decides:

• where each request goes
• whether it is allowed
• how it should be transformed, throttled, cached, or logged

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Main ways to control and route traffic

1. Route by path

Send requests to different backend services based on the URL.

Example:

• /users/* → User service
• /orders/* → Order service
• /payments/* → Payment service

2. Route by host or domain

Use different hostnames or subdomains.

Example:

• api.example.com/users → User service
• billing.example.com/* → Billing service

3. Route by headers

Use request headers to direct traffic.

Example:

• X-Version: v2 → New service version
• X-Tenant: premium → Premium cluster

4. Route by method

Different HTTP methods can go to different logic.

Example:

• GET /products → read-only backend
• POST /products → write backend

5. Route by query params or cookies

Useful for experiments, canary releases, or tenant-specific behavior.

Example:

• ?version=beta → beta backend

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Common traffic control features

Authentication and authorization

Enforce:

• API keys
• OAuth2 / JWT validation
• mTLS
• role-based access control

Rate limiting and quotas

Prevent abuse and control usage:

• requests per second
• per API key
• per tenant
• per IP address

Load balancing

Distribute traffic across multiple instances:

• round robin
• least connections
• weighted routing

Canary / blue-green deployment

Route a small percentage of traffic to a new version:

• 90% to v1
• 10% to v2

Request and response transformation

Modify traffic at the gateway:

• rewrite URLs
• add/remove headers
• transform payloads
• map protocols

Caching

Cache common responses at the gateway to reduce backend load.

Observability

Centralize:

• logs
• metrics
• tracing
• audit trails

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Typical implementation pattern

1. Define routes in the gateway
2. Attach policies to each route
3. Point clients to the gateway only
4. Let the gateway forward traffic to services based on rules

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Example routing logic

/api/v1/users/*   → user-service
/api/v1/orders/*  → order-service
/api/v1/admin/*   → admin-service (with stricter auth)
/api/v1/*         → default-service

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Tools that can do this

Depending on your stack:

• Kong
• NGINX / NGINX Plus
• Apigee
• AWS API Gateway
• Azure API Management
• Spring Cloud Gateway
• Traefik
• Envoy

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Best practices

• Keep routing rules simple and explicit
• Enforce security at the gateway, not in clients
• Version your APIs
• Use canary releases for safer deployments
• Monitor latency and error rates per route
• Avoid making the gateway too business-logic-heavy

If you want, I can also show you:

1. a real config example for NGINX, Kong, or Spring Cloud Gateway, or
2. a reference architecture diagram for a single gateway setup.