Custom errors

When the custom-http-errors option is enabled, the Ingress controller configures NGINX so that it passes several HTTP headers down to its default-backend in case of error:

Header	Value
`X-Code`	HTTP status code returned by the request
`X-Format`	Value of the `Accept` header sent by the client
`X-Original-URI`	URI that caused the error
`X-Namespace`	Namespace where the backend Service is located
`X-Ingress-Name`	Name of the Ingress where the backend is defined
`X-Service-Name`	Name of the Service backing the backend
`X-Service-Port`	Port number of the Service backing the backend
`X-Request-ID`	Unique ID that identifies the request - same as for backend service

A custom error backend can use this information to return the best possible representation of an error page. For example, if the value of the Accept header send by the client was application/json, a carefully crafted backend could decide to return the error payload as a JSON document instead of HTML.

!!! Important The custom backend is expected to return the correct HTTP status code instead of 200. NGINX does not change the response from the custom default backend.

An example of such custom backend is available inside the source repository at images/custom-error-pages.