content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements. See the NOTICE file distributed with this
   * work for additional information regarding copyright ownership. The ASF
   * licenses this file to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations under
   * the License.
   */
  package org.apache.bookkeeper.stats.prometheus;
  
  import io.prometheus.client.exporter.common.TextFormat;
  import java.io.IOException;
  import java.io.Writer;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  /**
   * Servlet used to export metrics in prometheus text format.
   */
  public class PrometheusServlet extends HttpServlet {
      private static final long serialVersionUID = 1L;
  
      private final transient PrometheusMetricsProvider provider;
  
      public PrometheusServlet(PrometheusMetricsProvider provider) {
          this.provider = provider;
      }
  
      @Override
      protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          resp.setStatus(HttpServletResponse.SC_OK);
          resp.setContentType(TextFormat.CONTENT_TYPE_004);
  
          Writer writer = resp.getWriter();
          try {
              provider.writeAllMetrics(writer);
              writer.flush();
          } finally {
              writer.close();
          }
      }
  
      @Override
      protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          doGet(req, resp);
      }
  
  }
  