Akka-http custom 404 page - akka-http

Question

I'd like to create a custom 404 page in akka-http (high level DSL). This basically means:
Return a page from my static folder (e.g. resources/www/404.html)
Set the result code to ResultCodes.NOT_FOUND
What I tried so far:
getFromResource - I can return the entity, but I can't figure out how to override the HTTP result code for the response, so I can set it to '404'.
complete() - I can return the right code, but I need to read the html page in manually, and build the HttpResponse from ground up. It eventually works, but it's a bit cumbersome.
Am I missing something? Is there an easier way to return a page and customize the result code?

Answer 1

The static page can be returned as the entity of an HttpResponse.
Assuming you have some function of the form
def someFunctionThatCanFail() : Try[HttpResponse] = ???
You will want to use your static page in the event of a failure. You'll first need to create a Source that is based on the static page:
import akka.stream.scaladsl._
import akka.http.scaladsl.model.HttpEntity.Chunked
def createStaticSource(fileName : String) =
FileIO
.fromPath(Paths get fileName)
.map(ChunkStreamPart.apply)
def createChunkedSource(fileName : String) =
Chunked(ContentTypes.`text/html(UTF-8)`, createStaticSource(fileName))
This source can then be placed inside of a response:
def staticResponse =
HttpResponse(status = StatusCodes.NotFound,
entity = createChunkedSource("resources/www/404.html"))
The only thing left to do is to either return the result of the function if it was valid or the static response in the case of a failure:
val route =
get {
complete(someFunctionThatCanFail() getOrElse staticResponse)
}

Answer 2

To expand on Ramon's excellent answer, this works inside a jar file as well:
def createChunkedSource(fileName : String): Chunked = {
def createStaticSource(fileName : String) : Source[ChunkStreamPart, Any] = {
val classLoader = getClass.getClassLoader
StreamConverters.fromInputStream(() => classLoader.getResourceAsStream(fileName)).map(ChunkStreamPart.apply)
}
Chunked(ContentTypes.`text/html(UTF-8)`, createStaticSource(fileName))
}