Gateway API Learning

This page contains examples demonstrating header-based routing in Gateway API. Header routing allows you to route traffic based on HTTP headers, which is useful for A/B testing, feature flags, environment routing, and user segmentation.

Header Matching

Gateway API supports native header matching, which is a significant advantage over Nginx Ingress where header-based routing requires custom server snippets.

Examples

Basic Header Matching

Routes traffic based on a single header value. This example routes to different services based on the X-Environment header.

Key Points:

Header matching is native in Gateway API (no annotations needed)
Headers are matched exactly by default
Can combine header matching with path matching
Default route handles requests without matching headers

Multiple Header Conditions

Shows AND logic (all headers must match) and OR logic (multiple matches). Demonstrates complex routing scenarios.

Key Points:

AND Logic: All headers in a single headers array must match
OR Logic: Multiple match blocks - any one can match
Useful for feature flags, user segmentation, and environment routing
Can combine with path matching for complex routing rules

Ingress Equivalent

For comparison, here's the equivalent Nginx Ingress configuration:

Note: Nginx Ingress requires server snippets for header routing, which is Nginx-specific and not portable.

Use Cases

Environment Routing: Route to staging/production based on headers
Feature Flags: Enable features for specific users or groups
A/B Testing: Route traffic to different service versions
User Segmentation: Route premium users to different backends
Canary Deployments: Gradually route traffic to new versions

Best Practices

Use Descriptive Header Names: Use clear, consistent header names (e.g., X-Environment, X-User-Type)
Combine with Path Matching: Use headers together with paths for more precise routing
Default Route: Always include a default route for requests without matching headers
Header Values: Be consistent with header value formats (case-sensitive)
Security: Don't rely on headers for security - validate on the backend

Header Routing