Custom Request/Response Filters

Spring Cloud Gateway offers many built-in filters, but sometimes you need very specific logic. Custom filters let you inject your own code into the request/response flow.

This allows for highly tailored processing, such as custom authentication checks, unique logging formats, or specific header manipulations.

To create a custom filter, you'll implement the GatewayFilter interface. This interface has one main method: filter().

• ServerWebExchange exchange: Provides access to the HTTP request and response.
• GatewayFilterChain chain: Allows you to pass the request to the next filter or the target service.

You'll also often implement Ordered to define your filter's execution priority.