api routing by header and path

If you mean routing API traffic based on both the request path and a header, the usual setup is:

• Path-based routing: /v1/users, /v2/users
• Header-based routing: route only if a header matches, e.g. X-Tenant: premium or Accept: application/vnd.myapi.v2+json
• Combined routing: both conditions must match

Common examples

1) NGINX

You can route using map + location:

map $http_x_api_version $backend {
    default         backend_v1;
    "2"             backend_v2;
}

server {
    listen 80;

    location /api/users {
        proxy_pass http://$backend;
    }
}

For more complex path + header logic, you can use if carefully or multiple location blocks.

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2) Kong / API Gateway

Most API gateways support this directly with routes like:

• Path: /api/users
• Header: X-API-Version: 2

Then forward to different upstream services.

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3) Express / Node.js

You can do header + path checks in middleware:

app.use('/api/users', (req, res, next) => {
  if (req.headers['x-api-version'] === '2') {
    return v2Handler(req, res);
  }
  return v1Handler(req, res);
});

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4) Spring Cloud Gateway

Route with predicates:

spring:
  cloud:
    gateway:
      routes:
        - id: users_v2
          uri: http://users-v2
          predicates:
            - Path=/api/users/**
            - Header=X-API-Version, 2
        - id: users_v1
          uri: http://users-v1
          predicates:
            - Path=/api/users/**

---

Pattern

Typically:

1. Match path first
2. Check header
3. Send to matching backend
4. Fallback if header missing or unknown

Example use cases

• API versioning
• A/B testing
• Canary releases
• Multi-tenant routing
• Feature flags

If you want, I can give you an example for a specific stack like NGINX, Kubernetes Ingress, AWS API Gateway, Kong, Spring Boot, or Express.