upload_proxy.rb

require 'goliath'
require 'em-synchrony/em-http'

class UploadProxy < Goliath::API

  def on_headers(env, headers)
    env.logger.info 'received headers: ' + headers.inspect
    env['async-headers'] = headers
  end

  def on_body(env, data)
    env.logger.info "received data #{data.size}"
    (env['async-body'] ||= '') << data
  end

  def on_close(env)
    env.logger.info 'closing connection'
  end

  def response(env)
    gh = EM::HttpRequest.new("http://localhost:8080/upload")
                  .post(:head => env['async-headers'],
                        :body => env['async-body'])

    gh.callback {
      logger.info "Received #{gh.response_header.status} from Upstream"
      env.stream_send gh.response
      env.stream_close
    }

    gh.error {
      env.stream_close
    }

    streaming_response(200, {'X-Stream' => 'Uploaddddd'})
  end


end

with_routes.rb

require 'goliath'
require 'em-synchrony/em-http'

require './upload_proxy'

class HealthCheck < Goliath::API
  def response(env)
    [200, {}, ["OK"]]
  end
end

class WithRoutes < Goliath::API

  get  "/healthcheck", HealthCheck

  post "/upload",      UploadProxy

end