# Interceptors

## Request interceptors

Request interceptors intercept whole request, and are called once for each request. They can provide additional endpoint interceptors, as well as modify the request, or the response.

The following request interceptors are provided by default (and if enabled, called in this order):

• the metrics interceptor, which by default is disabled

• the RejectInterceptor, which specifies what should be done when decoding the request has failed for all interpreted endpoints. The default is to return a 405 (method not allowed), if there’s at least one decode failure on the method, and a “no-match” otherwise (which is handled in an intereprter-specific manner)

## Endpoint interceptors

An EndpointInterceptor allows intercepting the handling of a request by an endpoint, when either the endpoint’s inputs have been decoded successfully, or when decoding has failed.

The following interceptors are used by default, and if enabled, called in this order:

• exception interceptor

• logging interceptor

• decode failure handler interceptor

Note that while the request will be passed top-to-bottom, handling of the result will be done in opposite order. E.g., if the result is a failed effect (an exception), it will first be logged by the logging interceptor, and only later passed to the exception interceptor.

Using customInterceptors on the options companion object, it is possible to customise the built-in interceptors, as well as add new ones in-between the default initial (exception, logging) and decode failure interceptors. Customisation can include removing the interceptor altogether. Later, interceptors can be added using .prependInterceptor and .appendInterceptor.