Ratpack HTTP Proxy

Ratpack.groovy

import org.slf4j.Logger
import org.slf4j.LoggerFactory
import ratpack.handling.Context
import ratpack.handling.Handler
import ratpack.http.client.HttpClient
import ratpack.http.client.StreamedResponse
import ratpack.http.MutableHeaders
import ratpack.http.client.RequestSpec

import static ratpack.groovy.Groovy.ratpack

final Logger log = LoggerFactory.getLogger(Ratpack.class);

class BlockedHostHandler implements Handler {
    def blockedHosts = ['www.asos.co.uk']

    @Override
    void handle(Context context) throws Exception {
        if (blockedHosts.contains(context.request.headers.host)) {
            context.redirect(302, "http://ratpack-foaas.herokuapp.com/you/no $context.request.headers.host allowed/the Boss")
        }

        context.next()
    }
}

ratpack {
    handlers {
        handler new BlockedHostHandler()

        handler { HttpClient httpClient ->
            log.info("Proxy to: $request.rawUri")

            httpClient.streamRequest(new URI(request.rawUri)) { RequestSpec spec ->
                spec.headers.copy(request.headers)
            } then { StreamedResponse responseStream ->
                responseStream.send(response) { MutableHeaders headers ->
                    def via = '1.1 Ratpack Proxy'
                    via = headers.get('Via') ? via + ', ' + headers.get('Via') : via
                    headers.set('Via', via)
                }
            }
        }
    }
}