HttpWebHandlerAdapter needs possibility to manipulate requests before their handle

[antechrestos]

Currently HttpWebHandlerAdapter handles requests as follows

1. handle x forwarded header which manipulates the request
2. instanciates exchange
3. instanciates observation context
4. run handle

My need was to populate traceparent from a X-Correlation-Id header. I was stuck as I would have need to insert something before point 3 and nothing was possible.

I ended by implementing a BeanPostProcessor which wraps the HttpHandler instance and manipulates request before anything, hence before point 1.

I would suggest something like

• create an interface the describe the manipulation of entering http request
• make the ForwardedHeaderTransformer implement it
• get all implementation when the HttpHandler is instanciated (instead of getting a nullable instance of ForwardedHeaderTransformer

Is this understandable?
I also think that it may lead ti misunderstanding with WebFilter.

Maybe the issue is with points 1 and 2 doing things out of the common lifecycle.

[bclozel]

This feature is already available. When building the HttpHandler with WebHttpHandlerBuilder, you can decorate it with the httpHandlerDecorator on that builder. In Spring Boot, you can contribute a WebHttpHandlerBuilderCustomizer bean to do that.

[antechrestos]

@bclozel ah ok thanks; my bad, I was looking 3.2.5 code version. I cannot migrate due to an issue I found in spring data mongo ..