Play! filter for performing access logging

AccessLogFilter.scala

object AccessLogFilter extends EssentialFilter {

  val dateTimeFormat = ISODateTimeFormat.ordinalDateTimeNoMillis()

  def apply(next: EssentialAction) = new EssentialAction {
    def apply(rh: RequestHeader) = {
      val startTime = System.currentTimeMillis()

      def logTime(result: PlainResult): Result = {
        val event = Json.obj(
          "uri" -> rh.uri,
          "timestamp" -> dateTimeFormat.print(new DateTime),
          "execution_time" -> (System.currentTimeMillis() - startTime),
          "status" -> result.header.status,
          "tags" -> Json.toJson(rh.tags.map(entry => entry._1.toLowerCase -> entry._2))
        )
        Logger.info(Json.stringify(event))
        result
      }

      next(rh).map {
        case plain: PlainResult => logTime(plain)
        case async: AsyncResult => async.transform(logTime)
      }
    }
  }
}