Hello any reason why if I read the bodyString of a response kotlinlang #http4k

Hello, any reason why if I read the bodyString of ...

Razvan

10/21/2020, 4:42 PM

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:

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@Test
    fun `response body string for html`() {
        val logAll = Filter { next: HttpHandler ->
            { request ->
                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, "<http://localhost:8080/static/index.html>"))
        response.status shouldBe 200
    }

static/index.html exists the filter prints it. the result:

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REQ: 
REP: <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Hello http4k</title>
</head>
<body>
    <h1>Hello http4k</h1>
</body>
</html>

***** RESPONSE 500 to GET: <http://localhost:8080/static/index.html> *****
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

10/21/2020, 4:52 PM

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

10/21/2020, 7:23 PM

@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

10/21/2020, 7:24 PM

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:

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val logAll = Filter { next: HttpHandler ->
        { request ->
            println("REQ: ${request.bodyString()}")
            val response = next(request)
            val bodyPayload = response.bodyString()
            println("REP: $bodyPayload")
            response.body(bodyPayload)
        }
    }

Razvan

10/21/2020, 7:40 PM

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

10/23/2020, 1:57 AM

@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 <<stream>>

➕ 1

Razvan

10/23/2020, 8:21 PM

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.

👍 1

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