Hello any reason why if I read the bodyString of a response

Question

Hello any reason why if I read the bodyString of a response of a static ressource like html file in a filter then the response is 500 and content lenght 0 here s a test ``` Test fun `response body string for html` val logAll = Filter next HttpHandler gt request gt println REQ $ request bodyString val response = next request println REP $ response bodyString response val server = logAll then routes static bind static ResourceLoader Classpath static asServer Undertow 8080 start val client = DebuggingFilters PrintResponse then OkHttp val response = client Request GET response status shouldBe 200 ``` static index html exists the filter prints it the result ```REQ REP < DOCTYPE html> lt html lang= en gt lt head gt lt meta charset= UTF 8 gt lt title gt Hello http4k lt title gt lt head gt lt body gt lt h1 gt Hello http4k lt h1 gt lt body gt lt html gt RESPONSE 500 to GET HTTP 1 1 500 Internal Server Error connection keep alive content length 0 content type text html date Wed 21 Oct 2020 16 41 37 GMT```

Razvan · Answer

Not that s useful to log a html page but I just added a filter that is logging api calls responses and didn t thought to disable it for the swagger static pages and I wasn t able to access the page took a bit to figure out I was just wandering if it s by design or a glitch

s4nchez · Answer

< Razvan> that s by design but I appreciate it s a common pitfall The error you re seeing is because by default static resources are served as streams and if you consume i e to print they are no longer available for undertow to push it through the wire that s why it breaks with `stream closed` exception invisible unless you debug it

s4nchez · Answer

The solution is trivial though if you want to use the static content on the server before pushing you need to reinject it into the body ```val logAll = Filter next HttpHandler gt request gt println REQ $ request bodyString val response = next request val bodyPayload = response bodyString println REP $bodyPayload response body bodyPayload ```

Razvan · Answer

Thanks Yes I thought it might be related to streaming the content I remember the pain of dealing with logging the stream body in Spring WebFlux I guess reinjecting works with text files but it brakes the binaries like images so better avoiding reading the bodystring of static content I don t know if it might help documenting that somewhere

dave · Answer

< Razvan> one thing you can do if you still want to see the traffic is to use the built in DebuggingFilters By default they don t consume the body if it s a stream just print lt lt stream gt gt

Razvan · Answer

Thanks yes I saw that I ll take a look how it detects if it s a stream maybe I can use the same to not log the streams I guess it may be helpful even for files upload unfortunately at work they are control freaks and want full requests and responses logged in json logtash so plain text won t do it