def observeKey(key: String): Observable[ByteBuf] = {
    var running = true
    var index: Option[String] = None
    def longPoll(obs: Observer[ByteBuf]) = {
      if (running) {
        val current = index.map("?index=" + _).getOrElse("")
        HttpClient.get(URL(s"$agent/$key$current").get).foreach({response =>
          if (response.status == Ok) {
            index = Some(response.headers.get("X-Consul-Index").get)
            response.getContent.foreach(obs.onNext)
          } else {
            running = false
            obs.onCompleted()
          }
        })
      } else {
        obs.onCompleted()
      }
    }
    Observable.create({ obs =>
      longPoll(obs)
      Subscription({running = false})
    })
  }